Work-readiness self report lift capacity test short form

Abstract

BACKGROUND:

The Multidimensional Task Ability Profile (MTAP) is a measure of self reported physical work capacity developed for injured workers with musculoskeletal disorders (MSDs) to determine readiness to return to work.

OBJECTIVE:

This study compared the concurrent validity of a new short form MTAP (MTAP-SF) comprised of 16 lifting and/or carrying items with the MTAP 55-item version. The hypothesis addressed is whether the validity of a version that imposes less respondent burden (MTAP-SF) would be comparable to the more burdensome instrument (MTAP-55).

METHODS:

MTAP scores were compared with demonstrated lift capacity in 1,252 healthy adults. Parallel regression analyses were conducted to examine the explanatory power of both MTAP versions.

RESULTS:

Age, gender, body mass and MTAP-SF explained 55% of the variance (p < 0.001) in demonstrated lift capacity, equivalent to MTAP-55.

CONCLUSIONS:

Self reported performance in physical work capacity tasks accounts for significant variance in lifting performance. MTAP-SF diminishes respondent burden while maintaining validity and may be useful for managing MSDs by enhancing understanding of the evaluee’s psychophysical component in return-to-work rehabilitation planning.

Keywords

Musculoskeletal disorders work capacity evaluation return to work functional capacity evaluation physical functional performance occupational health disability evaluation

1 Introduction

1.1 Importance of accurate psychophysical self-appraisal

The accuracy of psychophysical appraisal of maximum acceptable loads (MALs) for lifting, lowering, pushing, and pulling is pertinent to the work safety of healthy adults [1]. By extension, for people who are attempting to return to work after a disabling injury it is reasonable to expect that accurate psychophysical appraisal of MALs should be even more important. Inaccurate psychophysical perception of ability greater than actual ability places the worker at increased risk of overload injury, while perception of ability that is less than actual can unnecessarily constrain return to work options, especially for persons experiencing activity-related pain [2, 3].

Accurate psychophysical appraisal is especially important in chronic pain rehabilitation programs focused on return-to-work that follow the biopsychosocial (BPS) model. BPS presumes that the individual’s biological, psychological, and social domains interact and can be improved optimally by addressing all three on an integrated and rational basis, which requires accurate measures of each domain [2, 4]. The consistently successful functional restoration approach to what has otherwise appeared to be the intransigent problem of chronic pain rehabilitation for musculoskeletal disorders involves “an interdisciplinary team of clinicians who coalesce treatment around goals of restoring physical functional capacity and psychosocial performance” [2, p 125]. Whenever vocational outcomes are concerned, this involves serial examination of both work-relevant function and the patient’s cognitive appraisal of pain symptoms. Such an examination is facilitated by standardized measures of both sets of variables. Interdisciplinary pain management addresses maladaptive cognitions and functional deficits along with nociceptive dysregulation as interactive phenomena, recognizing that “the comprehensive assessment-treatment of all these dimensions is needed in order to be effective” [5]. In this approach, the patient negotiates with pain symptoms in response to gradually increasing physical challenges as their work capacity increases to the target job’s demands [6]. When the target job involves significant lifting tasks, periodic comparisons between measured lift capacity with self-perceived lift capacity as the patient progresses guide the rehabilitation process. To the degree that lift capacity increases, the ability of the person to return to work in a physically demanding job improves [7, 8].

1.2 Performance measurement of lift capacity

To address accurate psychophysical appraisal from a BPS perspective, several lift capacity tests with psychophysical components have been developed [9 –11] out of recognition that rational self-appraisal contributes to performance limits in physically demanding tasks; people tend to not attempt more than they perceive themselves capable [12 –14].

1.3 Self report measurement of general physical capacity versus work capacity

To quantify perceived physical ability that may affect patients’ performance in physically demanding tasks, self report measures of general physical ability in both everyday tasks [15 –18] and in work tasks [19 –22] have been developed. Items in the former set of measures have a ceiling much lower than items of the latter type. For example, the maximum lift examined with the PROMIS Physical Function (PF) measure is the ability “to lift and load one 50-pound (25 kg) bag of sand into a car” [23], while the Multidimensional Task Ability Profile includes five items involving lifting or carrying of 100-pound (45 kg) loads [24]. Both measures were developed using the Item Response Theory assessment model, although with different populations and for different purposes. The PROMIS PF was developed as a broad measure of ability to perform everyday physical tasks related to quality-of-life [18, 25], while the MTAP was designed to identify work readiness for rehabilitation patients in terms of the Dictionary of Occupational Titles [26]. The topmost of the five DOT physical demand characteristics (PDC) level (“Very Heavy”) requires lifting more than 100 pounds up to 33% of the workday but does not specify the maximum weight lifted [27]. The PROMIS ceiling reaches up to only the third PDC level (“Medium”).

1.4 Ceiling effect of lift capacity self report measurement

Although jobs that require lifting 100 pounds or more are relatively rare in the United States and Canada, they are likely to be more common in many developing countries. In a study of 3350 healthy normal American and Canadian adults, 126 (4%) reported jobs in the “Heavy” and “Very Heavy” categories requiring lifting and carrying of at least 100 pounds up to 33% of the workday, and 718 study Participants (21%) with jobs at or above the “Medium” PDC level, requiring lifting and carrying of at least 50 pounds [30].

Even though the MTAP items extend up to 100 pounds for lifting, a concurrent validity study with healthy normal adults that compared MTAP self reported physical capacity and Epic Lift Capacity Test performance [6] demonstrated an item-based ceiling effect with male Participants that was not present in prior studies of persons with musculoskeletal disorders. The items were not sufficiently demanding to fully encompass the upper range of lift tasks in competitive employment. Identification of the self report ceiling effect for return-to-work rehabilitation programs led to development of an expanded version of the MTAP that includes higher physical demand, the MTAP-55 with items that extend up to 150 pounds, as in Table 1. Although the 50-item MTAP includes two items in the very heavy PDC category, the addition of new very heavy items is likely important for people who are injured doing very heavy activities and is reflective of the needs of workers with very heavy occupational demands. Firefighters, for example, regularly perform very heavy activities including external loads above 100 pounds (45.4 kg), along with up to 80 pounds (36.3 kg) of gear [26, 27].

The expanded version (MTAP-55) adequately addressed ceiling effects, but respondent burden for time to completion became a concern with the addition of five new items. To address this concern, a short form of the MTAP (MTAP-SF) was developed by extracting the 16 items that depict lifting and/or carrying tasks, which would decrease respondent burden by more than 50%. The process for extraction and calibration of these items was similar to an earlier study by the current study’s authors that extracted 36 of the lifting and carrying items from the 111-item MTAP [28]. Briefly, an exploratory principal components factor analysis with varimax rotation was used to identify orthogonal factors in the 55 MTAP items. Next, a multi-step Rasch analysis was conducted to evaluate the characteristics of the MTAP’s 5-point rating scale and calculate each item’s response characteristics. Results of the Rasch analysis were used for item calibration and to rank items in order of difficulty [28]. From the ranked item set, 16 items were extracted to represent a range of lifting and carrying tasks, with an emphasis on those at the higher physical demand levels. These 16 items were used to form MTAP-SF.

Among the five new items in MTAP-55, two very heavy items were retained in MTAP-SF: 15. Lift a 125-pound (56.8 kg) crate from the ground to a truck bed. 16. Lift a 150-pound (68.2 kg) crate from the floor to eye-level. Thus, compared to the original MTAP-50 and new MTAP-55, MTAP-SF has a greater emphasis on very heavy activities, which comprise 25% (4/16) of the MTAP-SF items. As noted above, the purpose of adding two new very heavy items to MTAP-SF was to address the ceiling effect observed with MTAP-50. This premise was supported by unpublished data from recent research with full duty career firefighters in the United States (U.S. Department of Homeland Security, Grant #: EMW-2017-FP-00711. Approved by WCG IRB, Protocol #: 520190022). In a sample of 47 participants who completed MTAP-SF, item scores were lower for the two new very heavy items (15 and 16, described above) compared with the two existing very heavy items: 11. Push a full wheelbarrow up a ramp. 13. Carry a 100-pound (45.4 kg) crate for 50 feet (15.2 m), as follows (mean±SD, 0–4, higher score equals higher function): 11 : 3.81±0.65, 13 : 3.60±0.77, 15 : 3.36±1.05, 16 : 2.68±1.63. Further, more participants selected “unable” to perform the two new very heavy items compared with the two existing very heavy items, as follows: 11 and 13 : 0% (0/47) unable. 15 : 4.3% (2/47) unable. 16 : 21.3% (10/47) unable.

1.5 Purpose of the study

The purpose of the current study is to examine the concurrent validity of MTAP-55 with the new 16-item MTAP-SF in terms of the variance of lift capacity performance explained in healthy adults. The focus on healthy normal adults is important because this comparison is the appropriate target for successful completion of chronic pain rehabilitation focused on return-to-work.

2 Methods

2.1 Study design

This was an observational cohort study of healthy adults from the United States and Canada and Australia who were volunteer Participants in a training and certification program to prepare rehabilitation professionals (typically physical therapists and occupational therapists) to formally evaluate lift capacity. After a one-day training program followed by a knowledge examination, potential Certificants tested the lift capacity on a blind basis of five healthy adult Participants in a test-retest paradigm with a one-week interval. Before the retest, Participants were administered the online version of the MTAP-55, with the results masked from both the Certificant and the Participant.

2.2 Participants

This study enrolled a convenience sample of 1,358 generally healthy adults who were recruited by candidates for certification as an evaluator in the training program to administer the Epic Lift Capacity (ELC) test. Each potential Certificant recruited five healthy adult Participants who were typically family members, friends, and work colleagues. The Certificant must be a fully qualified and licensed or certified healthcare professional such as a Physical Therapist, Occupational Therapist, or Kinesiotherapist. After completing the training program, the Certificant must pass a written examination before administering the ELC to five healthy normal Participants on a test-retest basis with a one-week interval. This recruiting process and the subsequent screening-out of potential participants excluded from participation in the study for health reasons resulted in a convenience sample that was likely to be healthier than what would be expected in a random selection of adults in the United States and Canada. Potential limitations on the applicability of any findings to patients who are participating in clinical settings will be reviewed in the Discussion section.

After providing written informed consent approved by the first author’s institutional review board, Participants were screened with the health history questionnaire, resting heart rate and blood pressure measurement, and for health problems that might limit safe lift capacity administration of pertinent items from the Cornell Medical Index [29]. Potential Participants who reported cardiovascular signs and symptoms or musculoskeletal impairment, or who were found to have resting heart rate greater than 90 bpm or resting blood pressure greater than 159/100 mm Hg were excluded from participation.

2.3 Assessment of lift capacity

The EPIC Lift Capacity (ELC) test [10] was administered by the Certificant, deriving the Participant’s Maximum Acceptable Weight (MAW) lifted for each of six subtests, as operationally defined in the flow chart depicted in Fig. 1 that includes an ongoing psychophysical appraisal of the “safe and dependable” ability of the Participant. Details of ELC test administration are described elsewhere [10].

Fig. 1

Epic Lift Capacity Test Flowchart. Key: Black dots pattern fill indicates psychophysical variables reported by the evaluee. Papyrus texture fill indicates safety variables determined by the evaluator.

The ELC test process uses loads administered on a single-blind basis, known only to the evaluator. The first two of the six subtests begin with an empty lifting container weighing 10 lb. (4.5 kg). The test proceeds with loads increased in 10 lb. (4.5 kg) increments using masked weight canisters following the flowchart in Figure 1. Each of the remaining subtests begins with a load determined by formulae based on the MAW of the first two subtests. The Participant is not told the beginning weight nor the weight increments nor the MAW for any of the subtests. One week later, the Certificant retests the Participant. The summed MAW from the six subtests on the first occasion of testing is the dependent variable in this study. Prior research has demonstrated excellent test-retest reliability for this lift capacity test [10 , 31].

After testing, the testing records for each Participant were reviewed independently to assure that the Certificant had adhered to the ELC standard test procedures and the decision criteria to determine MAW using procedures and criteria depicted in Figure 1. Testing records that indicated poor adherence to these procedures and/or criteria were rejected and neither reviewed nor used in the current study. Incomplete datasets (such as missing body weight) and Participants who were eliminated as outliers or did not pass one of the MTAP or ELC inconsistent responding measures reduced the study to 1,252 (40% self-identified as male), with an age range of 18 years to 58 years and mean (SD) of 30.0 (8.50) years.

2.4 Assessment of self-perceived physical ability

Self-perceived physical ability testing was undertaken by the Participant with the 55-item MTAP, which was self-administered on an online basis at least one day after conclusion of the initial lift capacity test. The Certificant was blind to the MTAP results and the Participant was not provided with any score report or other response other than the final online computer screen “Thank You for Participatingq”.

As noted earlier, the MTAP 55 is a computer-administered and scored a pictorial activity task sort questionnaire [22, 32] developed with the Rasch rating scale model [33], so that each item and each item-by-response combination has a statistically-determined difficulty calibration. Each item is a combination of a short task description combined with a simple pictorial representation of an adult performing the task. Items are presented one at a time, beginning with physical demand below the United States Department of Labor’s Sedentary PDC level, and increasing to a level consistent with the “Very Heavy” PDC level [27]. The Participant responds to each item on a five-point rating scale from “Able” to “Unable”, with a “Don’t Know” option. To address the earlier-identified problem with the ceiling effect for healthy males [6], five items with high demands were added, as follows: Item 51 – Run one half-mile (0.8 km). 52 – Walk up and down three flights of stairs. 53 – Hike two miles (3.2 km) up and down hills. 54 – Lift a 125-pound (56.7 kg) crate from the ground to a truck bed. 55 – Lift a 150-pound (68 kg) crate from the floor to eye level. Each high-demand item candidate was comprised of a brief text description plus a pen and ink drawing of an adult performing the task, as in Figure 2.

Fig. 2

Sample MTAP Item. #55 on MTAP-55 (#16 on MTAP-SF).

From this total set of 55 items, all 16 items that involve lifting and/or carrying were selected to comprise the short-form MTAP-SF, as depicted in Table 1.

Table 1

Multidimensional Task Ability Profile Short Form (MTAP-SF) Items

Item	Task Description
1	Retrieve a small tool from the floor.
2	Unload two 10-pound (4.5 kg) grocery bags.
3	Unload a 20-pound (9.1 kg) grocery bag.
4	Carry a 20-pound (9.1 kg) sack of groceries for 50 feet (15.2 m).
5	Lift a 20-pound (9.1 kg) tool box from the floor to a bench.
6	Lift a 20-pound (9.1 kg) crate from the floor to eye-level.
7	Carry a 30-pound (13.6 kg) bucket in one hand for 50 feet (15.2 m).
8	Carry a 50-pound (22.7 kg) crate for 50 feet (15.2 m).
9	Lift a 50-pound (22.7 kg) crate from the floor to a bench.
10	Lift a 50-pound (22.7 kg) crate from the floor to eye-level.
11	Push a full wheelbarrow up a ramp.
12	Lift a 100-pound (45.4 kg) crate from the floor to a bench.
13	Carry a 100-pound (45.4 kg) crate for 50 feet (15.2 m).
14	Lift a 100-pound (45.4 kg) crate from the floor to eye-level.
15	Lift a 125-pound (56.8 kg) crate from the ground to a truck bed.^*
16	Lift a 150-pound (68.2 kg) crate from the floor to eye-level.^*

Key: ^*indicates a new item added to MTAP.

After the initial occasion of ELC testing and before the retest, MTAP data were collected from the Participant on a self-administered online basis and provided to the study staff without an opportunity for the Certificant to review. The delay in completing the MTAP online after conclusion of the first ELC test battery was Mean (SD) of 6.8 (3.2) days after the initial testing (range 1 to 20 days). The average score for all rated MTAP items was used as an independent variable because the values of a missed item and an item rated by the evaluee as “unable” are both zero. Thus, the average score for all rated items provides an uncontaminated indicator of the individual’s perceived ability.

2.5 Independent variables

Independent variables in this study included age, gender, and body mass, and the scores for the MTAP-55 and the MTAP-SF. The total possible score for MTAP-55 and MTAP-SF is 220 and 64, respectively. Age, gender, and body mass have been identified as significant contributors to lift capacity [31].

2.6 Data management

During the ELC testing process, the Participant’s data were recorded by the Certificant using forms designed for the study. After the second occasion of testing, the completed forms for both the test and retest were forwarded electronically or by mail to certification staff for review and approval of proper administrative procedures.

After the certification process was completed, the approved forms were provided to clerical staff who extracted pertinent data and matched the demographic and ELC data to MTAP data received independently from the Participant. The study staff anonymized each Participant’s record by assigning a research identification number and added the Participant’s record to a password-protected database. Data were maintained in Excel™ spreadsheets and analyzed with SPSS Statistics™ version 25 (Armonk, New York, USA).

2.7 Analysis

Analysis of the age, body mass, MTAP, and MAW variables began with examination of data distributions to consider potential outliers. To manage outliers, variables were standardized using a Z-score cutoff of 3.0 based on sample size and visual inspection of the data, a common procedure for human performance studies [34]. Separate one-way analyses of variance were undertaken to examine gender-based and age-based differences in both lift capacity data and MTAP data. To examine the first-order relationships among the variables, Pearson product-moment correlations were calculated. Using blocks of predictors, multiple regression analyses on the ELC total MAW were conducted. The first block included all demographic predictor variables (age, gender, body mass) and the second block added either of the two MTAP average scores. This approach allows control of impact based on gender, age, and body mass to examine the incremental contribution of the MTAP scores to predict lift capacity. Parallel regression analyses were conducted to examine the explanatory power of the MTAP-55 and the MTAP-SF in combination with the demographic variables of age, gender, and body mass.

3 Results

3.1 Participant characteristics

Out of the 1,358 Participants tested originally enrolled, 1,291 met the inclusion criteria. Their descriptive data are presented in Table 2. Listwise exclusions for missing data in correlational or comparative studies yielded 1,252 Participants for these analyses.

Table 2
Participant Characteristics

Variable Gender N M SD SE 95% CI Min Max

Lower Bound Upper Bound

Age (y) Female 780 30.16 8.67 0.31 29.55 30.77 18 58

Male 511 30.09 8.37 0.37 29.36 30.82 18 58

Total 1291 30.13 8.55 0.24 29.66 30.60 18 58

Height (cm) Female 780 165.65 6.71 0.24 165.18 166.12 142.24 185.42

Male 511 179.02 7.43 0.33 178.37 179.67 152.40 198.12

Total 1291 170.94 9.58 0.27 170.42 171.47 142.24 198.12

Body Mass (kg) Female 758 64.05 10.96 0.40 63.27 64.83 37.27 115.91

Male 504 81.79 12.61 0.56 80.69 82.90 50.00 125.00

Total 1262 71.13 14.53 0.41 70.33 71.94 37.27 125.00

BMI (kg/m²) Female 758 23.25 3.62 0.13 23.00 23.51 15.45 36.61

Male 504 25.43 3.32 0.15 25.14 25.72 17.23 36.28

Total 1262 24.12 3.66 0.10 23.92 24.33 15.45 36.61

MTAP-SF average (0–4) Female 781 2.68 0.58 0.02 2.64 2.72 1.19 4.00

Male 511 3.61 0.42 0.02 3.57 3.64 1.88 4.00

Total 1292 3.05 0.69 0.02 3.01 3.09 1.19 4.00

MTAP-55 average (0–4) Female 781 3.57 0.21 0.01 3.56 3.59 2.98 4.00

Male 511 3.88 0.14 0.01 3.86 3.89 3.27 4.00

Total 1292 3.69 0.24 0.01 3.68 3.71 2.98 4.00

MAW Total (kg) Female 774 111.84 31.49 1.13 109.62 114.06 27.27 256.82

Male 509 185.25 48.08 2.13 181.06 189.43 27.27 300.00

Total 1283 140.96 52.96 1.48 138.06 143.86 27.27 300.00

Variable	Gender	N	M	SD	SE	95% CI	Min	Max
Age (y)	Female	780	30.16	8.67	0.31	29.55	30.77	18	58
	Male	511	30.09	8.37	0.37	29.36	30.82	18	58
	Total	1291	30.13	8.55	0.24	29.66	30.60	18	58
Height (cm)	Female	780	165.65	6.71	0.24	165.18	166.12	142.24	185.42
	Male	511	179.02	7.43	0.33	178.37	179.67	152.40	198.12
	Total	1291	170.94	9.58	0.27	170.42	171.47	142.24	198.12
Body Mass (kg)	Female	758	64.05	10.96	0.40	63.27	64.83	37.27	115.91
	Male	504	81.79	12.61	0.56	80.69	82.90	50.00	125.00
	Total	1262	71.13	14.53	0.41	70.33	71.94	37.27	125.00
BMI (kg/m²)	Female	758	23.25	3.62	0.13	23.00	23.51	15.45	36.61
	Male	504	25.43	3.32	0.15	25.14	25.72	17.23	36.28
	Total	1262	24.12	3.66	0.10	23.92	24.33	15.45	36.61
MTAP-SF average (0–4)	Female	781	2.68	0.58	0.02	2.64	2.72	1.19	4.00
	Male	511	3.61	0.42	0.02	3.57	3.64	1.88	4.00
	Total	1292	3.05	0.69	0.02	3.01	3.09	1.19	4.00
MTAP-55 average (0–4)	Female	781	3.57	0.21	0.01	3.56	3.59	2.98	4.00
	Male	511	3.88	0.14	0.01	3.86	3.89	3.27	4.00
	Total	1292	3.69	0.24	0.01	3.68	3.71	2.98	4.00
MAW Total (kg)	Female	774	111.84	31.49	1.13	109.62	114.06	27.27	256.82
	Male	509	185.25	48.08	2.13	181.06	189.43	27.27	300.00
	Total	1283	140.96	52.96	1.48	138.06	143.86	27.27	300.00

Key: BMI: Body Mass Index. Gender: self-identified as female or male. MTAP-55 : 55-item version of the Multidimensional Task Ability Profile. MTAP-SF = 16-item short-form version of the Multidimensional Task Ability Profile. The average score across 55 items of MTAP-55 or 16 items of MTAP-SF was used for analysis. MAW Total: Maximum Acceptable Weight (MAW) lifted for each of six subtests of the EPIC Lift Capacity Test.

Frequency analysis of age found a mean (SD) of 30.7 (9.37) years and a median of 27.3 years, with kurtosis of 1.48 and skewness of 1.46, describing a relatively young sample. Separate one-way analyses of variance demonstrated no significant differences between males and females in terms of age (F1, 1289 = 0.019, p = 0.89), with significant differences in height (F1, 1289 = 1125.47, p < 0.001) and weight (F1,1260 = 703.28, p < 0.001) and BMI (F1,1260 = 116.90, p < 0.001) with males being taller, heavier, and with lower body mass indices. The total MAW lifted average was significantly greater for males than females (F1,1281 = 1092.01, p < 0.001). The score across all completed items was significantly greater for males than females for both the MTAP-SF (F1,1290 = 965.17, p < 0.001) and the MTAP-55 (F1,1290 = 840.48, p < 0.001). Table 3 describes the Pearson product-moment correlations among the variables.

Table 3

Correlations Among Variables

Variable	MAW Total	Gender	Age (yr)	Body Mass (kg)	MTAP-SF Average	MTAP-55 Average
MAW Total (kg)	1.00	–	–	–	–	–
Gender	0.68^*	1.00	–	–	–	–
Age (yr)	–0.03	0.01	1.00	–	–	–
Body Mass (kg)	0.56^*	0.60^*	0.14	1.00	–	–
MTAP SF average	0.63^*	0.65^*	–0.03	0.52^*	1.00	–
MTAP-55 average	0.62^*	0.63^*	–0.04	0.49^*	0.98^*	1.00

Key: N = 1,252. Values are Pearson product-moment correlation coefficients. ^*indicates p < 0.001 for the pairwise comparison. MAW Total: Maximum Acceptable Weight (MAW) lifted for each of six subtests of the EPIC Lift Capacity Test. Gender: self-identified as female or male. MTAP-55 : 55-item version of the Multidimensional Task Ability Profile. MTAP-SF = 16-item short-form version of the Multidimensional Task Ability Profile. The average score across 55 items of MTAP-55 or 16 items of MTAP-SF was used for analysis.

3.2 First order correlations

The correlations among the independent variables and total lift capacity were significant for all but the Participant’s age, likely reflecting the positive skew for age in this sample. The MTAP-55 average score accounted for 38.4% of the variance of total lift capacity, while the MTAP-SF average score accounted for 39.7% of the variance. Table 4 describes the results of these analyses.

Table 4
Summary of Regression Analyses for Predicting Lift Capacity from Self-Perceived Physical Ability and Demographic Variables

Variable Demographics Demographics+MTAP-55 Demographics+MTAP-SF

B β t α B β t α B β t α

Gender 58.00 0.54 21.44 0.000 43.03 0.40 14.69 0.000 42.26 0.39 14.20 0.000

Age –0.41 –0.07 –3.28 0.001 –0.29 –0.05 –2.38 0.017 –0.31 –0.05 –2.54 0.011

Body Mass 0.90 0.25 9.80 0.000 0.70 0.19 7.82 0.000 0.68 0.19 7.54 0.000

MTAP-55 60.93 0.27 10.88 0.000

MTAP-SF 21.25 0.28 10.73 0.000

R ² 0.51 0.55 0.55

F for R² change 423.72^* 118.46^* 115.18^*

Variable	Demographics	Demographics+MTAP-55	Demographics+MTAP-SF
Gender	58.00	0.54	21.44	0.000	43.03	0.40	14.69	0.000	42.26	0.39	14.20	0.000
Age	–0.41	–0.07	–3.28	0.001	–0.29	–0.05	–2.38	0.017	–0.31	–0.05	–2.54	0.011
Body Mass	0.90	0.25	9.80	0.000	0.70	0.19	7.82	0.000	0.68	0.19	7.54	0.000
MTAP-55					60.93	0.27	10.88	0.000
MTAP-SF									21.25	0.28	10.73	0.000
R ²	0.51	0.55	0.55
F for R² change	423.72^*	118.46^*	115.18^*

Key: N = 1,252. ^*indicates p < 0.001. Lift Capacity: Maximum Acceptable Weight (MAW) lifted for each of six subtests of the EPIC Lift Capacity Test. Demographics: gender, age, body mass. Gender: self-identified as female or male. Self-Perceived Physical Ability: from the Multidimensional Task Ability Profile (MTAP). MTAP-55 : 55-item version of MTAP. MTAP-SF: 16-item short-form version of the MTAP. The average score across 55 items of MTAP-55 or 16 items of MTAP-SF was used for analysis.

Both MTAP versions explain meaningful variance in lift capacity. Use of the MTAP-SF in clinical practice focused on return-to-work in physically demanding jobs provides practical guidance and tracking of work-relevant progress with low response burden and clinical expense.

3.3 Blocked multiple regression analyses

In the first block, demographic predictors accounted for 51% of the variance in lift capacity (F3,1248 = 423.72, p < 0.001). Adding the MTAP-55 to the second block found the combination of predictor variables accounting for 55% of the variance (F4,1247 = 377.31, p < 0.001), a statistically significant increment (t = 10.88, p < 0.001) in explanatory power. Substituting the MTAP-SF in the second block found the combination of predictor variables also accounted for 55% of the variance (F4,1247 = 375.66, p < 0.001), a statistically significant increment (t = 10.73, p < 0.001).

Therefore, in combination, age, gender, body mass and the 16-item MTAP-SF explained 55% of the variance in total lift capacity, equivalent to the MTAP-55. Although gender and body mass are the primary predictors of lift capacity, MTAP significantly increases variance explained. MTAP’s contribution is on par with body mass. The amount of variance attributable to gender emphasizes the need for gender-specific normative data. Subsequent analyses revealed a significant effect (p < 0.05) of gender on the MTAP average score, with higher scores for males. However, no significant effect of age or age by gender interaction on the MTAP average score was observed, reflecting the strong positive skew in this data set. Normative data by gender and percentile rank for the MTAP-SF average score are shown in Table 5.

Table 5
MTAP-SF Normative Data – Average Score by Gender

Female Male

N 780 511

Mean 2.68 3.61

SD 0.58 0.42

Skew 0.32 –1.39

Kurtosis –0.31 1.79

Range 2.81 2.13

Minimum 1.19 1.88

Maximum 4.00 4.00

Percentile Rank

5 1.81 2.75

10 1.95 3.00

15 2.06 3.13

20 2.19 3.31

25 2.25 3.40

30 2.38 3.50

35 2.44 3.56

40 2.50 3.63

45 2.56 3.69

50 2.63 3.75

55 2.69 3.81

60 2.75 3.81

65 2.85 3.88

70 2.94 3.94

75 3.06 3.94

80 3.19 4.00

85 3.38 4.00

90 3.50 4.00

95 3.75 4.00

	Female	Male
N	780	511
Mean	2.68	3.61
SD	0.58	0.42
Skew	0.32	–1.39
Kurtosis	–0.31	1.79
Range	2.81	2.13
Minimum	1.19	1.88
Maximum	4.00	4.00
Percentile Rank
5	1.81	2.75
10	1.95	3.00
15	2.06	3.13
20	2.19	3.31
25	2.25	3.40
30	2.38	3.50
35	2.44	3.56
40	2.50	3.63
45	2.56	3.69
50	2.63	3.75
55	2.69	3.81
60	2.75	3.81
65	2.85	3.88
70	2.94	3.94
75	3.06	3.94
80	3.19	4.00
85	3.38	4.00
90	3.50	4.00
95	3.75	4.00

Key: MTAP-SF: 16-item short-form version of the Multidimensional Task Ability Profile. Average Score: Average score across 16 items of MTAP-SF. Gender: self-identified as female or male.

4 Discussion

4.1 Utility of psychophysical data

Lift capacity is determined by the contemporaneous contributions of the person’s biomechanical, cardiorespiratory, and psychophysical systems. A self report pictorial activity task sort (PATS) such as the MTAP facilitates performance testing by improving the evaluator’s understanding of the evaluee’s psychophysical self-appraisal [6]. This was prohibited in the research study but is recommended practice for clinicians who are working with patients who have physical impairments so that a rational approach to psychophysical self-appraisal is encouraged. The PATS method of item construction allows the practitioner to inquire, “As you see yourself performing this task (indicating the picture) what causes you to be (slightly, moderately, severely) restricted?” The evaluee’s responses allow the practitioner to conduct an informed assessment of lift capacity and provide improved interpretation of the results for increased specificity of a safe and appropriately challenging exercise prescription. The first-order comparison between the MTAP-SF score and the maximum acceptable weight lifted (Table 3) indicates a likelihood of good utility for serial testing of progress in a functional restoration or work hardening program. For example, confirmation of demonstrated lift capacity in a functional capacity evaluation contemporaneous with the MTAP-SF at the beginning of rehabilitation, followed by serial self report testing to confirm progress seems to be reasonable, and is made more efficacious by its diminished patient response burden. In an occupational health setting, for example screening for return to physically demanding work after recovery from an injury or illness or pregnancy, administration of the MTAP-SF may be useful to identify the need for a performance evaluation. The previously-demonstrated predictive validity of the MTAP for adequate lift capacity [30] based on the Dictionary of Occupational Titles [26, 27] suggests that the MTAP-SF may have utility for such screening.

4.2 Respondent burden

An advantage of MTAP-SF is that it decreases response burden by about two-thirds compared to MTAP-55, while maintaining concurrent validity. A previous study demonstrated that the time to complete the 50-item MTAP-2 (not including instructions) was 4.7 to 8.1 minutes, depending on which timepoint (initial or follow-up test) and language (English or Spanish) the test was administered [35]. Thus, MTAP-SF could save approximately 3 to 5 minutes for each test administration, which can be valuable in certain clinical settings. In outpatient physical therapy, for example, multiple functional performance tests are regularly performed and often include at least one patient-reported outcome (PRO) measure, which is required by Merit-based Incentive Payment System (MIPS) program of the U.S. Centers for Medicare & Medicaid Services [36]. Our recent experience with a clinical quality improvement project at two private outpatient physical therapy centers (Spine & Sport Physical Therapy Inc, San Diego, California, USA) suggests that decreasing respondent burden through administration of streamlined PROs, such as MTAP-SF (vs. MTAP-55), could be a useful element among other various clinical strategies to improve patient adherence [37]. Completion of the MTAP-55 in addition to the MIPS-required PRO is advised whenever return-to-work decisions are being considered near the conclusion of a treatment program.

4.3 Performance variance accounted for by self report

This was the second study to examine the concurrent validity of MTAP questionnaires with regard to the lift capacity of healthy Participants [6]. The slightly greater degree of variance accounted for by the 16-item MTAP-SF is likely due to restricting the selection of items to those that involve lifting and carrying tasks, while the 55-item MTAP-55 includes tasks such as handling and fingering along with lifting and carrying. In clinical settings that focus on spinal tasks for patients with lifting demands at work, the MTAP-SF can be recommended.

4.4 Contributions of demographic variables

The coherence of lift capacity with body mass and gender is well-established in the research literature [38]. The substantial correlations between the MTAP scores and each of these variables reflect this natural coherence and underscores the validity of self report scores that vary from gender norms. In addition, this suggests the potential utility of a derived variable based on the quotient of total MAW divided by body mass as a species-wide criterion of fitness for physically demanding work tasks. This requires further study because such a derived variable theoretically should approach gender neutrality if the vertical displacement of the task is considered, given comparable fitness levels and age. This may prove to be useful in screening prior to post-offer employment testing to minimize adverse impact by parsing fitness level that may be contaminating gender or age considerations.

4.5 Pragmatic applications

The conjoint use of self report measures and performance testing on a serial basis has been the operational expression of the biopsychosocial model of rehabilitation since its inception [39 –42]. Increased sensitivity to mismatched self-perception in physical capacity improves the utility of the assessment findings by guiding intervention.

4.6 Work-oriented patient self report

A previous study demonstrated the concurrent validity of the 50-item MTAP-2 in terms of several established self report measures [43]. The current study supports the use of the MTAP-SF to specifically support the psychophysical components of a biopsychosocial approach that focuses on lift capacity. When lifting presents a significant functional limitation and is also an important aspect of a patient’s job demands, information about fear of potential reinjury, pain avoidance, or injury catastrophizing can be very useful. In these circumstances, the MTAP-SF can provide the rehabilitation team with a broadened perspective on issues that may be of concern to the patient and therefore necessary to address. Because psychophysical self-appraisal imposes limits on physical function [12], use of the MTAP-SF on a serial basis may be helpful to identify a patient’s overly cautious response to rehabilitation. This new instrument may also be useful to track improvement and progress during rehabilitation [44]. If administered serially over the course of a rehabilitation program, improvement in lift capacity may be monitored to confirm the patient’s progress and identify when a plateau has occurred in anticipation of program cessation. In addition to avoiding the exposure of the patient to overload injury from repetitive physical testing, the time and expense required for serial performance testing of lift capacity can be minimized.

4.7 Reasonable accommodations negotiations

Return-to-work negotiations among the injured employee, their work supervisor, the employer’s safety team, and the healthcare team concerning reasonable accommodations to facilitate return to work require that each stakeholder’s perspective is clearly understood. This can be improved using pictorial task descriptions in comparison to the job description. When this occurs, “facilitated return to work” meets the spirit of disability rights legislation [45], and has been demonstrated to be quite effective [46], consistent with the following description of clinical significance:

“Occupational safety and medical personnel need to engage early and often with injured workers, supervisors, and adjusters to better manage the medical care and return to work process with the aim of achieving superior disability and cost outcomes” (ibid p 828).

Pictorial self report measures such as the MTAP facilitate injured workers’ ability to communicate their perceived residual physical limitations during this negotiation. “As you see yourself performing this task, why did you rate yourself as slightly restricted?” is an example of a question that bridges the gap between the injured worker and the professionals facilitating a safe and dependable return to work. The text and pictorial nature of each item increases the likelihood that ergonomic specificity can be addressed much better than reliance on only a text description of the task. The current research provides validation that a short pictorial self report measure focused on lifting would be reasonable to use for occupations in which lifting is an essential function. Moreover, in questionable cases, following up with a performance-based functional capacity evaluation that includes a related lifting test calibrated to the self report test can help address issues such as fear or recalcitrance that may be clouding the return-to-work negotiations.

4.8 Injury prevention screening in an aging workforce

In addition to occupational rehabilitation programs, worksite health and wellness programs may benefit from the MTAP-SF. As a brief screening measure requiring less than five minutes to complete, its use as an early intervention tool may have efficacy to prevent overload injuries in an aging workforce. Identification of mismatches between the employee’s strength and their lifting and/or carrying has been shown to reduce the incidence and severity of work-related injuries [47]. In addition to screening an aging workforce in order to minimize risk of overload injuries, age-based and gender-based normative data reflect real differences in physical capacity that can be considered in employee assignments.

4.9 Study limitations

A limitation of this study was that a convenience sample, while large was enrolled from generally healthy individuals who were full duty workers without disability or clinical MSDs. While item response theory was used to develop each MTAP version, providing an item-calibrated basis for construct validation for work capacity and lift capacity in injured workers, research is needed to replicate this study in individuals with MSDs and are out of work. It is likely that psychosocial factors and idiosyncratic responses to chronic pain, among other issues that were not present in the study participants, will influence the relationship between self report data and performance data in persons receiving treatment for chronic pain and work disability. Future research is also necessary to examine the application of MTAP-SF and MTAP-55 in periodic screens to assess the match between the employee’s work capacity and their occupational demands.

5 Conclusions

Summary

This study examined the concurrent validity of a short form of the MTAP in terms of its ability to account for lift capacity in a large sample of healthy adults. The 16-item MTAP-SF was derived from the 55-item MTAP that included five new high-demand items to address a problem with ceiling effects found in use of the 50-item MTAP-2 in a healthy-normal male population. The MTAP-SF demonstrated excellent validity, accounting for 55% of the variance in lift capacity, equivalent to MTAP-55. Thus, self reported performance accounts for significant variance in lifting test performance. In situations in which the focus is on lift capacity rather than a broader range of work-related physical demands, the MTAP-SF provides a more efficient alternative, reducing respondent burden by about two-thirds without sacrificing validity, and therefore is a reasonable substitute for the MTAP-55.

Acknowledgements and declarations

Ethical considerations and disclosures

All procedures followed were in accordance with the ethical standards of the responsible committee on human experimentation and with the Helsinki Declaration of 1975, as revised in 2000.

Informed consent

Prior to participation, each Participant provided written informed consent approved by the first author’s Institutional Review Board.

Conflicts of interests

LM has proprietary interests in the MTAP and ELC. LM, JV, and JM are board members of The Vert Mooney Research Foundation, which owns the MTAP, from which JM received employee compensation.

Footnotes

Acknowledgments

The authors gratefully acknowledge the contributions to data collection by Karen Markley, Lisa Markley, Sherry McCowan, and Kristen Del Real of EpicRehab, and Erin Matheson of Matheson Development. For this study, LM contributed to conceptualization, methodology, software, validation, analysis, data interpretation, investigation, resources, data curation, preparation of the original manuscript draft, review and edits of subsequent manuscript drafts, supervision, project administration, manuscript administration, and acquired funding for this study. JV and JM contributed to conceptualization, analysis, data interpretation, data curation, preparation of the original manuscript draft, review and edits of subsequent manuscript drafts, and manuscript administration. LM, JV, and JM have read and agreed to the published version of themanuscript.

Funding

Epic Neurorehabilitation and Psychology Services, Inc. and the 501(c)(3) non-profit Vert Mooney Research Foundation funded this research.

References

Potvin

, Ciriello

, Snook

, Maynard

, Brogmus

. The Liberty Mutual manual materials handling (LM-MMH) equations. Ergonomics. 2021;64(8):955–70.

Gatchel

, McGeary

, Lippe

. Interdisciplinary chronic pain management: Past, present, and future. Am Psychol. 2014;69(2):119.

Bevers

, Watts

, Kishino

, Gatchel

. The biopsychosocial model of the assessment, prevention, and treatment of chronic pain. US Neurol. 2016;12(2):98–104.

Brecht

, Gatchel

. An overview of a biopsychosocial model of epigenetics and pain catastrophizing. J Appl Biobehav Res. 2019;24(3):e12171.

Gatchel

, Peng

, Peters

, Fuchs

, Turk

The biopsychosocial approach to chronic pain: Scientific advances and future directions. Psychol Bull. 2007;133(4):581.

Mooney

, Matheson

, Verna

, Leggett

, Dreisinger

, Mayer

. Performance-Integrated self report Measurement of Physical Ability. Spine J. 2010;10(1):433–40.

Matheson

, Isernhagen

, Hart

. Relationships among lifting ability, grip force, and return to work. Phys Ther. 2002;82(3):249–56.

Gross

, Battie

, Cassidy

The prognostic value of functional capacity evaluation in patients with chronic low back pain: Part 1: Timely return to work. Spine. 2004; 29(8):914–9.

Mayer

, Barnes

, Kishino

, Nichols

, Gatchel

, Mayer

, Mooney

. Progressive isoinertial lifting evaluation. I. a standardized protocol and normative database. Spine. 1988;13:993–7.

10.

Matheson

, Mooney

, Grant

, Affleck

, Hall

, Melles

, et al. A test to measure lift capacity of physically impaired adults. Part 1 Development and reliability testing. Spine. 1995;20:2119–29.

11.

Isernhagen

, Hart

, Matheson

. Reliability of independent observer judgements of level of lift effort in a kinesiophysical functional capacity evaluation. Work. 1999;12:145–50.

12.

Borg

. Psychophysical bases of perceived exertion. Med and Sci in Sports and Exercise. 1982;14(5):377–81.

13.

Snook

. Psychophysical acceptability as a constraint in manual working capacity. Ergonomics. 1985;28(1):331–5.

14.

Troup

, Foreman

, Baxter

, Brown

. The perception of back pain and the role of psychophysical tests of lifting capacity. Spine. 1987;12(7):645–57.

15.

Fairbank

, Couper

, Davies

, O’Brien

. The Oswestry low back pain disability questionnaire. Physiotherapy. 1980;66(8):271–3.

16.

Roland

, Morris

A study of the natural history of back pain: Part 1: Development of a reliable and sensitive measure of disability in low back pain. Spine. 1983;8:141–4.

17.

Cella

, Riley

, Stone

, Rothrock

, Reeve

, Yount

, et al. The Patient-Reported Outcomes Measurement Information System (PROMIS) developed and tested its first wave of adult self reported health outcome item banks: 2005–2008. Journal of Clinical Epidemiology. 2010;63(11):1179–94.

18.

Rose

, Bjorner

, Becker

, Fries

, Ware

. Evaluation of a preliminary physical function item bank supported the expected advantages of the Patient-Reported Outcomes Measurement Information System (PROMIS). Journal of clinical epidemiology. 2008;61(1):17–33.

19.

Matheson

, Matheson

, Grant

. Development of a measure of perceived functional ability. J Occup Rehabil. 1993;3(1):15–30.

20.

Mayer

, Mooney

, Verna

, Udermann

, Matheson

, Dreisinger

. Reliability and Validity of the Multidimensional Task Ability Profile. Medicine & Science in Sports & Exercise. 2003;35(5):S144.

21.

Matheson

. History, design characteristics, and uses of the pictorial activity and task sorts. J Occup Rehabil. 2004;14(3):175–95.

22.

Mayer

, Mooney

, Matheson

, Leggett

, Verna

, Balourdas

, DeFilippo

. The reliability and validity of a new computerized pictorial activity and task sort. J Occup Rehabil. 2005;15(2):185–95.

23.

PROMIS^® Item Bank v2.0 Physical Function [Internet]. PROMIS Health Organization and PROMIS Cooperative Group. 2023 [cited 8/04/2023].

24.

Matheson

, Sarkin

, Mayer

, Mooney

, Verna

, Leggett

, editors Calibration of the difficulty of work activities and activities of daily living for patients with spinal pain. North American Spine Society 22nd Annual Meeting; 2007 October 23-27, 2007; Austin, TX.

25.

Brodke

, Zhang

, Shaw

, Cizik

, Saltzman

, Brodke

. How Do PROMIS Scores Correspond to Common Physical Abilities? Clinical Orthopaedics and Related Research^®. 2022;480(5):996–1007.

26.

U.S. Department of Labor. Dictionary of Occupational Titles. 4th ed. Washington, DC: United States Government Printing Office; 1991.

27.

U.S. Department of Labor. The Revised Handbook for Analyzing Jobs. Washington, DC: Author; 1991.

28.

Matheson

, Mayer

, Mooney

, Sarkin

, Dreisinger

, Verna

, Leggett

. A method to provide a more efficient and reliable measure of self report physical work capacity for patients with spinal pain. J Occup Rehabil. 2008;18(1):46–57.

29.

Abramson

, Terespolsky

, Brook

, Kark

. Cornell Medical Index as a health measure in epidemiological studies: A test of the validity of a health questionnaire. Br J Prev Soc Med. 1965;19(3):103–10.

30.

Matheson

, Verna

, Dreisinger

, Leggett

, Mayer

. Age and gender normative data for lift capacity. Work. 2014;49(2):257–69.

31.

Matheson

. Relationships among age, body weight, resting heart rate, and performance in a new test of lift capacity. J Occup Rehabil. 1996;6:225–37.

32.

Matheson

, Mooney

, Leggett

, Mayer

, Verna

, Driesinger

, et al. Multidimensional Task Ability Profile. San Diego: Vert Mooney Research Foundation; 2003.

33.

Andrich

. Rasch Models of Measurement. Newbury Park:Sage; 1988.

34.

Cousineau

, Chartier

. Outliers detection and treatment: A review. Int J Psychol Res. 2010;3(1):58–67.

35.

Verna

, Matheson

, Gables

, Hause

, Mayer

. Development and reliability testing of Spanish language and English language versions of the multidimensional task ability profile. J Occup Rehabil. 2013;23(2):220–7.

36.

U.S. Centers for Medicare & Medicaid Services. Traditional MIPS Overview: U.S. Centers for Medicare & Medicaid Services; 2023 [Available from: https://qpp.cms.gov/mips/traditional-mips.

37.

Jimenez

, Mortimer

, Rheaume

, Weinberg

, Lopez

, Verna

, Mayer

Implementation of function-based outcomes systems in physical rehabilitation: A quality improvement project. American College of Sports Medicine Annual Meeting; June 2023; Denver, CO2023.

38.

Hydren

, Borges

, Sharp

. Systematic review and meta-analysis of predictors of military task performance: Maximal lift capacity. J Strength Cond Res. 2017;31(4):1142–64.

39.

Matheson

, Ogden

, Violette

, Schultz

. Work Hardening: Occupational Therapy in Industrial Rehabilitation. Am J Occup Ther. 1985;39(5):314–21.

40.

Gatchel

, Mayer

, Capra

, Diamond

, Barnett

. Quantification of lumbar function. Part The use of psychological measures in guiding physical functional restoration. Spine. 1986;11(1):36–41.

41.

Feuerstein

, Beattie

Biobehavioral factors affecting pain and disability in low back pain: Mechanisms and assessment. Phys Ther. 1995;75(4):267–80.

42.

Papciak

, Feuerstein

. Psychological factors affecting isokinetic trunk strength testing in patients with work-related chronic low back pain. J Occup Rehabil. 1991;1(2):95–104.

43.

Verna

, Matheson

, Scherer

, Mayer

. Validity of the Multidimensional Task Ability Profile. J Occup Rehabil. 2019;29:822–31.

44.

Robinson

, Kishino

, Matheson

, Woods

, Hoffman

, Unterberg

, et al Improvement in postoperative and nonoperative spinal patients on a self report measure of disability: The Spinal Function Sort (SFS). J Occup Rehabil. 2003;13(2):107–13.

45.

EEOC. Notice Concerning the Americans with Disabilities Act (ADA) Amendments Act of 2008. United States Equal Employment Opportunity Commission; 2009.

46.

Bernacki

, Kalia

, Soistman

, Minor

, Barry

, Lavin

, Tao

. Prevention, Medical Management, and Adjudication of Workplace Injuries: A Thirty-Two Year Follow-up of an Integrated Workers’ Compensation Program. JOEM. 2021; 63(10):828.

47.

M-L

, Putz-Anderson

, Garg

, Davis

. Evaluation of the impact of the revised National Institute for Occupational Safety and Health lifting equation. Hum Factors. 2016;58(5):667–82.