Validity and reliability of the Turkish version of the Physical Workload Questionnaire

Abstract

BACKGROUND:

Although it is necessary to regularly record and assess physical workloads in a workplace to prevent work-related musculoskeletal disorders, there is no easy to use, valid and reliable questionnaire such as the Physical Workload Questionnaire (PWQ) in Turkish.

OBJECTIVE:

To linguistically and culturally adapt the PWQ into Turkish, and to examine the validity and reliability of this adapted version.

METHODS:

One hundred twenty-six participants were recruited. All participants filled in the Oswestry Disability Index (ODI) and the Nordic Musculoskeletal Questionnaire. To determine test-retest reliability, all participants filled in the PWQ after a time interval of one week.

RESULTS:

There was a significant difference in the PWQ indices between the participants with an occupation requires less vs. higher workload (p < 0.05). The PWQ index was significantly correlated with the proximal musculoskeletal symptoms (ρ= 0.301, p < 0.05), but not significantly correlated with distal musculoskeletal symptoms (ρ= 0.121, p > 0.05). The PWQ index was significantly correlated with the ODI (ρ= 0.193, p < 0.05). The internal consistency of the PWQ was excellent (α= 0.865) and item-total correlations were acceptable. Test-retest reliability was high (ICC = 0.865).

CONCLUSIONS:

The PWQ is the unique valid and reliable questionnaire available in Turkish for assessing physical workload due to body posture and strenuous effort during work.

Keywords

Reliability validity physical workload Turkey work-related disorder musculoskeletal disorder

1 Introduction

Work-related musculoskeletal disorders (MSDs) are an important occupational concern in the relationship between work and disease [1]. Work-related MSDs not only reduce quality of life, but they are also the most expensive type of work disability that accounts for about 40% of all costs for the treatment of work-related injuries [2]. Work-related MSDs are also associated with a sickness absence in a variety of occupations, including healthcare workers, and are among the leading causes of sickness absence in Europe [3].

Many cross-sectional and retrospective studies have indicated that physical workload is inversely related to physical functioning among middle-aged and aging workers and an increased risk of work-related MSDs is associated with a high physical workload [4, 5]. Healthcare workers constitute a group with high exposition to physical factors including awkward postures, manual material handling, repetitive tasks and others [6]. These tasks are physically demanding and impose mechanical loads on the back that increase the probability for the development of low back pain and disability [7 –9].

Although the physical work environment has improved substantially, preventing work-related MSDs and sickness absence remains a challenge [3]. The assessment of physical workload in the workplace is emerged as a key issue to prevent work-related MSDs [10]. The most commonly used method for assessing physical workload is a self-reported questionnaire that provides specific benefits compared to alternative methods such as observation and direct measures [10, 11]. Biomechanical modelling can be a valuable tool for combining multiple exposures faced in a workplace, which may contribute to spinal loading, into a common metric, such as lumbar spine compressive forces [7]. The Physical Workload Questionnaire (PWQ) developed by Hollmann et al. was based on a sophisticated biomechanical model describing forces in the lumbar spine during work activities [12]. The estimated physical workload index with the PWQ varies little over time, discriminates among workers in different occupation categories, and is associated with musculoskeletal complaints [12]. The PWQ provides a calibration procedure that links subjective assessments in a questionnaire to objective estimates of physical workload with more advanced techniques [11].

Although it is necessary to regularly record and assess physical workloads in a workplace to prevent work-related MSDs, there is no easy to use, valid and reliable questionnaire such as the PWQ in Turkish. Therefore, the aim of this study was to linguistically and culturally adapt the PWQ into Turkish, and to examine the psychometric properties of this adapted version.

2 Methods

2.1 Participants

One hundred twenty-six participants were recruited between June 2014 and November 2014. The participants were registered healthcare staff members (i.e. not interns or trainees) who were working at the Dokuz Eylül University Hospital. Different departments were randomly visited during working hours to collect data. The study was discussed with the Head of Departments, who then informed the staff members. The questionnaires were given to all staff members willing to participate in the study. This study was a part of a large project about the musculoskeletal problems among workers which was approved by the Ethics Committee of Dokuz Eylül University (registration number: 1336-GOA) and previous studies have published [9, 13]. All participants provided informed consent before participating in the study.

2.2 Cross-cultural adaptation

The permission for the cross-cultural adaptation was granted by Scandinavian Journal of Work, Environment & Health where the original PWQ study was published [12]. The cross-cultural adaptation was undertaken according to the published guideline [14]. The forward translation was the first step. Native Turkish-speaking translators translated the PWQ into Turkish. One of the translators was not informed about the study. Two translations were synthesized and a combined translation was prepared. The back-translations were performed by two translators whose mother tongue was English which was the original language of the PWQ. The translators, who performed the back-translations, were with no medical background and not informed regarding the concepts explored in the study. The expert committee, which included physiotherapists and laypeople, consolidated all versions (i.e. two Turkish and two back-translated English) of the PWQ. The pre-final version of the PWQ was developed for the pilot study.

2.3 Validity

2.3.1 Pilot study to assess face and content validity

Randomly selected 20 healthcare staff members from the Dokuz Eylül University Hospital completed the pre-final Turkish version of the PWQ. The pilot study was conducted to ensure that the Turkish version of the PWQ was understandable and that the context of the PWQ had not changed. Face validity was assessed by the expert committee with evaluating the layout, language, instructions, response format and clarity of the items in the pre-final Turkish version of the PWQ [15]. The participants were also interviewed with regard to the wording, terminology, instructions, and clarity of the response options. The participants read the questions and verbally evaluated the items in terms of their comprehensibility. They were invited to recommend items for deletion or modification. The members of the expert committee indicated whether each item on the PWQ was congruent with, and relevant to, its underlying construct [16]. The percentage of items deemed to be relevant by each expert was computed, and then the average of the percentages across the experts was obtained to assess content validity [16]. After the pilot study, the final Turkish version of the PWQ was prepared.

2.3.2 Construct, convergent and discriminant validity

The pilot study showed that the Turkish version of the PWQ had good face validity. There is no available questionnaire in Turkey for assessing physical workload to serve a gold standard for assessing validity of the PWQ. Because the validity refers to the extent to which scores on a particular measure relate to other measures, consistent with theoretically derived hypotheses concerning the constructs that are being measured, we used the Nordic Musculoskeletal Questionnaire (NMQ) and Oswestry Disability Index (ODI) [17]. We hypothesized that the higher disability assessed by the ODI should be correlated with higher PWQ index since the PWQ calculates the forces in the lumbar spine during work activities. Therefore, the ODI was used to assess the construct validity of the PWQ. The convergent and discriminant validity were also examined. We hypothesized that the correlations of the PWQ index with the proximal musculoskeletal symptoms should be higher (convergent validity) than with the distal musculoskeletal symptoms (discriminant validity) assessed by the NMQ. The power of the PWQ to discriminate between workers in different occupation groups was also examined. For this purpose, physicians and medical secretaries were determined as occupations which require less physical workload and nurses, service or cleaning staff members as occupations which require higher physical workload.

2.4 Reliability

The internal consistency and test–retest reliability were determined for the Turkish version of the PWQ. The participants were asked to complete the PWQ twice, with an interval of 1 week, to assess its test-retest reliability. This period was considered sufficient to avoid participants remembering their previous responses, and to prevent variations in the observed phenomena that could affect the repeatability [18].

2.5 Instruments

2.5.1 The Physical Workload Questionnaire

The PWQ includes 19 items describing different work situations [12]. The items are also presented as pictograms. Five of the items describes postures of the trunk (in the following text the item identifications are given in parentheses): straight, upright (T1) (trunk bent 5 degrees forward), slightly inclined (T2) (trunk bent 45 degrees forward), strongly inclined (T3) (trunk bent 75 degrees forward), twisted (T4), and laterally bent (T5). Three items ask for the following positions of the arms: two arms below shoulder height (Al), one arm above shoulder height (A2), and two arms above shoulder height (A3). Five items ask for positions of the legs: sitting (L1), standing (L2), squatting (L3) (trunk bent 15 degrees forward), kneeling on one or both knees (L4), and walking or moving (L5). Six items describe the lifting of weights. Three concerns lifting with the trunk upright (Wu1-Wu3) and three with the trunk inclined 60 degrees (Wi1-Wi3). Each set of three items ask for lifting of light weights (<10 kg; Wu1 & Wi1), medium weights (10–20 kg; Wu2 & Wi2) and heavy weights (>20 kg; Wu3 & Wi3). All the items are answered in a Likert-type scale with five choices from never to very often (never = 0, seldom = 1, sometimes = 2, often = 3, very often = 4). The PWQ index is calculated according to this formula: 0.974 x score of T2 + 1.104 x score of T3 + 0.068 x score of T4 + 0.173 x score of T5 + 0.157 x score of A2 + 0.314 x score of A3 + 0.405 x score of L3 + 0.152 x score of L4 + 0.152 x score of L5 + 0.549 x score of Wu1 + 1.098 x score of Wu2 + 1.647 x score of Wu3 + 1.777 x score of Wi1 + 2.416 x score of Wi2 + 3.056 x score of Wi3 [12].

2.5.2 The Oswestry Disability Index

The ODI is the most commonly used outcome measure for low back pain [19]. It contains items about the intensity of pain, lifting, ability to care for oneself, ability to walk, ability to sit, sexual function, ability to stand, social life, sleep quality, and ability to travel. Each of these categories comprises six statements describing different potential scenarios; the subject chooses the statement that most closely resembles their situation. The ODI is currently considered as the gold standard for measuring the degree of disability in a person with low back pain, and the Turkish version of the ODI has good comprehensibility, internal consistency, and validity [20].

2.5.3 The Nordic Musculoskeletal Questionnaire

The NMQ includes 27 items exploring the presence of musculoskeletal symptoms during a 12-month period covering in nine different parts of the body (i.e. neck, shoulders, elbows, wrists/hands, upper back, lower back, hips/tights, knees, ankles/feet) [21]. It also has items pertaining to severity grades, determined according to functional status and the presence of musculoskeletal symptoms during the last seven days. The Turkish version of the NMQ has appropriate psychometric properties, including good test–retest reliability, internal consistency and construct validity [13]. We calculated a total musculoskeletal symptom load with the method described by Hollmann et al. [12]. The items of the NMQ were coded as follows: neither symptoms nor restrictions = 0, symptoms in the last 12 months but not in the last 7 days and no restrictions = 1, symptoms in the last 12 months and either symptoms in the last 7 days or restrictions = 2, symptoms in both the last 12 months and the last seven days and, in addition, restrictions = 3. Then the scores obtained from upper and lower back, neck, shoulders, and hips/tights were summed as the proximal musculoskeletal symptoms. The scores obtained from the remaining body regions were summed as the distal musculoskeletal symptoms. Because the proximal and distal regions do not have equal numbers of body parts, the summed score of the proximal musculoskeletal symptoms were divided by 5 and the summed score of the distal musculoskeletal symptoms were divided by 4.

2.6 Statistical analyses

Descriptive statistics were used to evaluate the participants’ characteristics. The internal consistency of the Turkish version of the PWQ was assessed by calculating and categorizing Cronbach’s alpha coefficients as follows: excellent, >0.80; adequate, 0.70–0.79; and inadequate, <0.70 [22]. Furthermore, the intra-class correlation coefficient (ICC) was calculated to assess the test-retest reliability. The degree of reliability was reported as very low for ICC≤0.25, low for ICC = 0.26–0.49, moderate for ICC = 0.50–0.69, high for ICC = 0.70–0.89, and very high for ICC≥0.90 [23]. The Spearman correlation test was used to evaluate the validity. Since the data were not normally distributed, the PWQ indices among the different occupational groups was compared with the Mann-Whitney U test. The level of significance was determined at p < 0.05. The data were analyzed using the IBM SPSS Statistics software (ver. 23.0; IBM Corp.).

3 Results

In total, 126 participants were included in the study. There were 61 medical secretaries, 23 nurses, 28 care or cleaning staff, and 14 physicians. Of these, 75 participants’ occupation (59.5%) were classified as an occupation requiring less physical workload (i.e. medical secretaries and physicians). Remaining 51 participants’ occupation were classified as an occupation requiring higher physical workload. There were 88 female participants (69.8%). The median age of all participants was 36.0 (IQR, 30.0–44.0) years. The median work experience duration was 11.75 (IQR, 4.62–20.87) years and the median weekly working time was 40.0 (IQR, 40.0–48.0) hours. Characteristics of the participants are presented in Table 1.

Table 1
Characteristics of the participants (N = 126)

Variables Frequency or median Percentage or interquartile range

Gender

Female 88 69.8%

Male 38 30.2%

Age (years) 36.0 30.0–44.0

Body mass index (kg/m²) 24.93 22.05–28.68

Occupation

Medical secretary 61 48.4%

Nurse 23 13.8%

Service or cleaning staff 28 26.7%

Physician 14 11.1%

Occupation characteristic

Requires less physical workload 75 59.5%

Requires higher physical workload 51 40.5%

Work experience (years) 11.75 4.62–20.87

Weekly working time (hours) 40.0 40.0–48.0

Musculoskeletal symptom loads^†

Proximal 0.8 0.4–1.2

Distal 0.5 0–1.0

Physical Workload Questionnaire index 27.04 21.61–36.63

Oswestry Disability Index (%) 37 24–50

Variables	Frequency or median	Percentage or interquartile range
Gender
Female	88	69.8%
Male	38	30.2%
Age (years)	36.0	30.0–44.0
Body mass index (kg/m²)	24.93	22.05–28.68
Occupation
Medical secretary	61	48.4%
Nurse	23	13.8%
Service or cleaning staff	28	26.7%
Physician	14	11.1%
Occupation characteristic
Requires less physical workload	75	59.5%
Requires higher physical workload	51	40.5%
Work experience (years)	11.75	4.62–20.87
Weekly working time (hours)	40.0	40.0–48.0
Musculoskeletal symptom loads^†
Proximal	0.8	0.4–1.2
Distal	0.5	0–1.0
Physical Workload Questionnaire index	27.04	21.61–36.63
Oswestry Disability Index (%)	37	24–50

^†Assessed by the Nordic Musculoskeletal Questionnaire.

No evidence of floor or ceiling effects was found on the Turkish version of the PWQ, with no participants having ≤5% and only 3 participants having ≥95% of the PWQ index.

3.1 Validity

The expert committee decided that the layout, language, instructions, response format and clarity of the items were good. The participants from the pilot study reported no difficulty with regard to the wording, terminology, instructions, and clarity of the response options. All of the committee experts rated 100% of the items as being congruent with their underlying construct (17). Content validity was therefore established at 100%. Therefore, the Turkish version of the PWQ had adequate face and content validity.

As pre-hypothesized, there was a significant difference in the PWQ indices between the participants with an occupation requiring less vs. higher workload (p < 0.05). Correlations between the PWQ index and the other study variables are presented in Table 2. In summary, the PWQ index was significantly correlated with the proximal musculoskeletal symptoms (ρ= 0.301, p < 0.05), but not significantly correlated with distal musculoskeletal symptoms (ρ= 0.121, p > 0.05). The PWQ index was also significantly correlated with the ODI (ρ= 0.193, p < 0.05). These results have indicated that the Turkish version of the PWQ has good construct, convergent and discriminant validity.

Table 2
Correlations between the Physical Workload Questionnaire index and the other study variables

Variables 1 2 3 4 5 6 7 8

1. Physical Workload Questionnaire index –

2. Age –0.121 –

3. Gender^† 0.254^* 0.083 –

4. Body mass index (kg/m²) 0.009 0.285^* 0.258^* –

5. Work experience (years) –0.117 0.717^* –0.008 0.101 –

6. Weekly working time (hours) 0.235^* –0.180^* 0.058 0.158 –0.228^* –

7. Proximal musculoskeletal symptom load 0.301^* –0.058 –0.298^* –0.191^* 0.077 0.105 –

8. Distal musculoskeletal symptom load 0.121 –0.039 –0.278^* –0.096 0.057 0.029 0.608^* –

9. Oswestry Disability Index 0.193^* 0.126 –0.260^* –0.069 0.194^* 0.003 0.567^* 0.363^*

Variables	1	2	3	4	5	6	7	8
1. Physical Workload Questionnaire index	–
2. Age	–0.121	–
3. Gender^†	0.254^*	0.083	–
4. Body mass index (kg/m²)	0.009	0.285^*	0.258^*	–
5. Work experience (years)	–0.117	0.717^*	–0.008	0.101	–
6. Weekly working time (hours)	0.235^*	–0.180^*	0.058	0.158	–0.228^*	–
7. Proximal musculoskeletal symptom load	0.301^*	–0.058	–0.298^*	–0.191^*	0.077	0.105	–
8. Distal musculoskeletal symptom load	0.121	–0.039	–0.278^*	–0.096	0.057	0.029	0.608^*	–
9. Oswestry Disability Index	0.193^*	0.126	–0.260^*	–0.069	0.194^*	0.003	0.567^*	0.363^*

^*p < 0.05. ^†Female and male were coded as 1 and 2, respectively.

3.2 Reliability

The internal consistency of the Turkish version of the PWQ for all items, measured by the Cronbach’s alpha coefficient, was excellent (α=0.812). Item-total correlations for all items ranged from –0.340 to 0.60. Table 3 presents inter-item reliability of the Turkish version of the PWQ. However, the items T1, A1, L1 and L2 are not used for calculation of the PWQ index. Therefore, we conducted second item-total correlation analysis for the remaining 15 items which showed that the internal consistency increased by 3% (α= 0.838) and item-total correlations were acceptable ranged from 0.286 to 0.576. Table 4 presents the second analysis for the inter-item reliability of the Turkish version of the PWQ. Test-retest reliability for the Turkish version of the PWQ was high (ICC = 0.865 with 95% confidence interval = 0.808–0.905).

Table 3
Inter-item reliability of the Turkish version of the Physical Workload Questionnaire (for all items)

Items Corrected item-total correlations Cronbach’s alpha if item deleted

Trunk

T1. Straight, upright 0.265 0.812

T2. Slightly inclined 0.345 0.806

T3. Strongly inclined 0.493 0.798

T4. Twisted 0.396 0.804

T5. Laterally bent 0.383 0.804

Arms

A1. Both arms below shoulder height 0.276 0.811

A2. One arm above shoulder height 0.430 0.802

A3. Both arms above shoulder height 0.375 0.805

Legs

L1. Sitting –0.340 0.846

L2. Standing 0.516 0.797

L3. Squatting 0.600 0.793

L4. Kneeling with one knee or with both 0.428 0.803

L5. Walking, moving 0.479 0.799

Weight, lifted/carried with upright trunk

Wu1. Light (up to 10 kg) 0.525 0.795

Wu2. Medium (10–20 kg) 0.540 0.796

Wu3. Heavy (more than 20 kg) 0.488 0.799

Weight, lifted/carried with inclined trunk

Wi1. Light (up to 10 kg) 0.442 0.801

Wi2. Medium (10–20 kg) 0.496 0.798

Wi3. Heavy (more than 20 kg) 0.461 0.800

Items	Corrected item-total correlations	Cronbach’s alpha if item deleted
Trunk
T1. Straight, upright	0.265	0.812
T2. Slightly inclined	0.345	0.806
T3. Strongly inclined	0.493	0.798
T4. Twisted	0.396	0.804
T5. Laterally bent	0.383	0.804
Arms
A1. Both arms below shoulder height	0.276	0.811
A2. One arm above shoulder height	0.430	0.802
A3. Both arms above shoulder height	0.375	0.805
Legs
L1. Sitting	–0.340	0.846
L2. Standing	0.516	0.797
L3. Squatting	0.600	0.793
L4. Kneeling with one knee or with both	0.428	0.803
L5. Walking, moving	0.479	0.799
Weight, lifted/carried with upright trunk
Wu1. Light (up to 10 kg)	0.525	0.795
Wu2. Medium (10–20 kg)	0.540	0.796
Wu3. Heavy (more than 20 kg)	0.488	0.799
Weight, lifted/carried with inclined trunk
Wi1. Light (up to 10 kg)	0.442	0.801
Wi2. Medium (10–20 kg)	0.496	0.798
Wi3. Heavy (more than 20 kg)	0.461	0.800

Table 4

Inter-item reliability of the Turkish version of the Physical Workload Questionnaire (for 15 items)

Items	Corrected item-total correlations	Cronbach’s alpha if item deleted
Trunk
T2. Slightly inclined	0.286	0.838
T3. Strongly inclined	0.540	0.823
T4. Twisted	0.431	0.830
T5. Laterally bent	0.427	0.830
Arms
A2. One arm above shoulder height	0.415	0.831
A3. Both arms above shoulder height	0.386	0.833
Legs
L3. Squatting	0.576	0.822
L4. Kneeling with one knee or with both	0.405	0.832
L5. Walking, moving	0.360	0.835
Weight, lifted/carried with upright trunk
Wu1. Light (up to 10 kg)	0.509	0.826
Wu2. Medium (10–20 kg)	0.566	0.822
Wu3. Heavy (more than 20 kg)	0.489	0.827
Weight, lifted/carried with inclined trunk
Wi1. Light (up to 10 kg)	0.511	0.825
Wi2. Medium (10–20 kg)	0.551	0.823
Wi3. Heavy (more than 20 kg)	0.489	0.827

4 Discussion

In this study, the PWQ was successfully cross-culturally adapted into Turkish. The Turkish version of the PWQ showed to be a valid and reliable questionnaire for assessing physical workload due to body posture and strenuous effort during work. The results of this study is important because the Turkish version of the PWQ is the only one available questionnaire in Turkey to assess physical workload.

No evidence of floor or ceiling effects was found on the Turkish version of the PWQ and it had an adequate face and content validity. The predefined hypotheses regarding the correlations between the PWQ, ODI, proximal and distal musculoskeletal symptoms were confirmed. The PWQ index was significantly correlated with the ODI and proximal musculoskeletal symptoms. On the other hand, the PWQ index was not significantly correlated with distal musculoskeletal symptoms. Our results were similar as the original study which indicated that there were significant correlations between the PWQ index and proximal musculoskeletal symptoms (ρ= 0.21–0.35), and there were not significant correlations between the PWQ index and distal musculoskeletal symptoms (ρ= 0.13–0.19) (10). Although the occupation categories in the current study are different from the original study including nursing, service, social work, and management staff members, the PWQ index could also differentiate between the occupation groups such as medical secretary and physician vs. nurse and service/cleaning staff [12]. The participants with an occupation requiring higher workload has significantly higher PWQ index than the participants with an occupation requiring less workload. The correlations between the PWQ index and ODI have indicated that the higher forces in the lumbar spine during work activities might cause higher low back pain and disability. Overall, these results have indicated that the Turkish version of the PWQ has good construct, convergent and discriminant validity.

The internal consistency of the Turkish version of the PWQ for all items was excellent; however, not all the item-total correlations were acceptable. This is because the items T1, A1, L1 and L2 are not used for calculation of the PWQ index, they are accepted that they do not measure the same construct. Actually, these items indicate the standard positions which do not cause physical workload on spine. Therefore, the second item-total correlation analysis for the remaining 15 items was conducted and it has revealed that the internal consistency increased by 3% and all item-total correlations have been acceptable. However, it does not necessary to remove the items T1, A1, L1 and L2. As the original study suggests, these items must be surveyed to investigate the characteristics of an occupation [12]. Test-retest reliability for the Turkish version of the PWQ was high, similarly with the original study which reported the test-retest reliability was about 0.60 [12]. In summary, these results have indicated that the Turkish version of the PWQ is a reliable measure.

Because there are many exposures in a workplace that may cause spinal loading, it is not sufficient to investigate one exposure at a time when comparing occupation groups or settings or evaluating interventions [7]. Therefore, the biomechanical modelling can be used as a valuable tool for combining multiple exposures into a common metric, such as lumbar spine compressive forces. Low back modelling in laboratory settings has been used to describe exposures of healthcare staff in work-related tasks in several studies [24 –26]. However, these laboratory-based methods require expensive equipment and experienced personnel. The PWQ, on the other hand, is not just a simple questionnaire but also it uses a sophisticated biomechanical model describing forces in the lumbar spine. Additionally, there is no available questionnaire in Turkish to assess physical workload. Therefore, the PWQ is a promising self-reported tool to assess physical workload in large studies.

The present study had some limitations. Firstly, the participants were randomly selected for the pilot study. Although participants from all education levels were included by chance, the proportion of participants in each category were not controlled, which could have implications for the comprehensibility data. Secondly, all of the questionnaires were administered in the same order, which could have created an order effect. Lastly, the operational qualities such as the percentage of participants who completed the PWQ autonomously and the time taken to do so were not evaluated.

5 Conclusion

This study has suggested that the Turkish version of the PWQ is a valid and reliable instrument. Thus, this study has introduced the unique questionnaire available in Turkish to assess physical workload due to body posture and strenuous effort during work. The PWQ can be used to determine and then prevent high-risk work-related tasks. The PWQ can also provide information about threshold levels of physical exposures for work safety. Additionally, the PWQ can be used to prevent work-related MSDs among the workers in different occupational industries with better understanding of physical workloads.

Conflict of interest

The authors declare that there are no conflicts of interest.

Funding

The authors completed the manuscript without the aid of any type of funding.

Footnotes

Acknowledgments

We would like to express our sincere thanks to Pembe Keskinoglu, Prof, MD from Department of Biostatistics and Medical Informatics, Dokuz Eylül University for statistical help and advice.

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