Reliability and validity study of the Gujarati version of the Oswestry Disability Index 2.1a

Abstract

BACKGROUND:

Among all musculoskeletal disorders back pain is the most common reason for functional limitation in working age. It is due to low back pain (LBP) that the ODI has become one of the principal outcome measures for evaluation of disability and has been widely used in research as well as in clinical practice. So far, validated Gujarati version of the ODI 2.1a has not been reported.

OBJECTIVE:

To accomplish the translation and validation of the Oswestry Disability Index (ODI) version 2.1a into the Gujarati language.

STUDY DESIGN:

Cross-sectional study.

METHODS:

The validation of the ODI-Gujarati was tested in 120 patients diagnosed with non-specific LBP, who were receiving physiotherapy at a clinic in Gujarat, India. Data was collected at on initial visit and after 48 hours. During both visits, patients completed the Oswestry Disability Index-Gujarati (ODI-G), Roland-Morris Disability Questionnaire-Gujarati (RMDQ-G), and Visual Analogue Scale-Pain (VAS-P).

RESULTS:

Internal consistency was measured by Cronbach’s alpha. The Gujarati version indicated high internal consistency ( $\alpha=$ 0.96). Test-retest reliability was measured by intra-class correlation coefficient and it revealed very high correlation (ICC $=$ 0.92). Construct validity was confirmed by strong correlation with RMDQ-G ( $r=$ 0.76), and concurrent validity indicated moderate correlation with VAS-P ( $r=$ 0.50). Factor analysis explained that the ODI was loaded on 1 factor.

CONCLUSION:

The Oswestry disability index version 2.1a was successfully translated into Gujarati language, showing excellent psychometric properties. Therefore, it can be used in evaluating the disability amongst Gujarati population with LBP for both clinical and research purposes.

Keywords

ODI-Gujarati version 2.1a low back pain reliability validity

1. Introduction

Musculoskeletal disorders a major health problem across the globe and are few of the most frequent causes of disability [1, 2]. Among these disorders low back pain (LBP) is the fifth most common reason resulting into physician visits that are present with many possible etiologies and affect erratically [1, 2, 3]. In western countries, it has become a growing concern about disability associated with back pain. In United States, an estimated 6.5 million population are bed-ridden due to back pain [1, 2].

Nearly, 60–65% of Indian population also suffers from back pain in their lifetime [4]. The lifetime prevalence rate of LBP is reported to be as high as 84% and the prevalence of chronic low back pain is about 23%. Twelve percent of the population is already disabled by low back pain; it can lead to early retirement and common reason for short and long-term work sick-leave. Economically, LBP is a huge burden on health care system and on socio-economic status [1, 2, 3].

Almost 85% of patients are affected by nonspecific LBP, and are defined as any type of back pain in the lumbar region that is not related to identifiable pathologies such as malignancy, systemic inflammatory disorders, infections, fractures and nerve root compression [5]. Non-specific low back pain can be associated with a number of reasons including injury to the back, muscle strain, overuse, incorrect physical activities, frequent lifting, psychological distress, poor posture and many others [5].

In LBP patients, measurements of disability are necessary for assessment and make a treatment plan [1]. In treating these patients, it is necessary to evaluate the level of severity of the symptoms and level of disability [3]. The patients reported outcome measure (PROMs) are completed by patients to measure their perceptions of their own functional status and wellbeing [6].

Outcome measures for low back pain are numerous including Oswestry Disability Index (ODI) [16], Roland Morris Disability Questionnaire (RMDQ) [24], Waddell disability index [26], Quebec back pain disability scale [27], and SF-36 [28]. Of all of these we have selected ODI as it has been found to be valid and reliable tool and is used worldwide to measure pain and disability resulting due to low back pain.

The Oswestry Disability Index (ODI) is a self-reported outcome measure considered as the gold standard for evaluating level of disability and estimating quality of life in person with low back pain [7, 8, 9, 10]. According to the ODI website, the questionnaire is translated in 29 different languages and all of them were found to be reliable and valid in comparison with the original English version [12, 13].

The ODI was already validated in several languages spoken across the world like Hindi, Tamil, Finnish, Arabic, Italian, Colombia, Brazilian Portuguese, German, Marathi, Danish, Korean, Greek, Norwegian, Hungarian, Nepali, French-Canadian, Chinese, Iranian and Turkish. India is a country with diversity, having 29 states, 7 union territories and 20 official languages. Gujarati is a language that is spoken across the globe and is an official language of Gujarat state in India.

The original English version of ODI is designed to provide the requirements of patients in western countries; it is not useful in patients whose primary language is Gujarati. No validated Gujarati version of the ODI has been reported. Hence, it becomes evident that it is quite difficult for the patients to understood and follow the questionnaire as the language acts as a barrier.

2. Material and methods

This translation study was approved by Institution review board of Ashok & Rita Patel Institute of Physiotherapy, Charotar University of Science & Technology with ethical clearance number ARIP/IRB/15/36 and patients written consent was sought prior to their participation in the study.

2.1 Subjects

The psychometric properties of the Oswestry Disability Index-Gujarati (ODI-G) were examined in 120 [29] Gujarati speaking nonspecific LBP patients receiving physiotherapy at a clinic in Gujarat, India. Inclusion criteria were: subjects of both the sexes with nonspecific LBP (Age 18–60 years), who were able to read, write, and speak Gujarati language and could complete the questionnaire. Exclusion criteria were: patients with neurological deficit, pregnancy, operative procedure within 6 months and menstrual low back pain. Data was collected at the initial visit and after 48 hours. During both visits patients completed ODI-G, RMDQ-G, and VAS-P.

2.2 Translation and cross-cultural adaptation

Dr. Jeremy Fairbank suggested validating ODI version 2.1a. Permission to translate the ODI into Gujarati was obtained from MAPI, copyright owner of the ODI. Five step guidelines for evaluation of psychometric properties offered by Beaton and Guillemin [13, 14] were followed:

III. I.
Forward translation: The forward translation into Gujarati was performed independently by two translators who were bilingual in Gujarati and English. The first translator had medical background and was aware about ODI. The second translator did not have medical background and was unaware about ODI. Two forward translations were done in this stage.
II.
Synthesis of the translations: Both forward translated versions were compared and analyzed in a meeting between two translators and the authors, and they formed a common synthesis.
III.
Back translation: The synthetic Gujarati version was again translated into English by two different translators who were bilingual in Gujarati and English. This stage completed two back translations.
IV.
Expert committee review: An expert committee includes the authors, all translators, an orthopedist, methodologists and language professionals. Firstly, each member was asked to evaluate the equivalence of all items and the answers between the source and target version in four areas: semantic, idiomatic, experiential and conceptual. Moreover, the committee discussed issue of cultural adaptations of original English version of the ODI. Based on which a pre-final Gujarati version of ODI was prepared.
V.
Test of the pre-final version: The pre-final version of the ODI-G was tested among 15 Gujarati speaking patients with nonspecific low back pain, cognitive debriefing was done individually. In this test, comprehension, confusing phrasing, ambiguous meaning and emotional words were checked and it was seen whether the translated version retained similarity to the English version.

The final Gujarati version 2.1a of the ODI was finally completed by 120 patients with nonspecific back pain for psychometric testing.
2.3 Questionnaire booklets

The questionnaire package included ODI-G, RMDQ-G, and VAS-P. The ODI is self-reported questionnaire that contains ten items including pain intensity, personal care, lifting, ability to walk, ability to sit, ability to stand, sleep quality, sexual function, social life, and ability to travel. Each section has 6 responses, scored on a scale of 0–5 with the first statement being zero and indicating no disability and the last statement that score with 5 indicates greater disability [16]. If more than one answer was chosen by the patient, the highest score was calculated.

RMDQ is self-completed measure of disability for the patients with low back pain. It consists of 24 items related to disability caused due to LBP. The RMDQ score ranges from 0 (no disability) to 24 (maximum disability) [24].

The pain intensity was assessed using the visual analog scale for pain (VAS-P). It is also self-reported, valid and reliable measure in terms of pain assessment. It has a 100-mm horizontal line with the left end marked as “no disability” and the right end marked as a “severe pain” [30].

2.4 Evaluation of psychometric properties

2.4.1 Reliability

Reliability is defined as the ability of a measurement to differentiate between subjects or objects. Reliability demonstrates homogeneity and reproducibility, in that, homogeneity consists of internal consistency of a scale while reproducibility consists of test-retest reliability of scores [39].

Patients with nonspecific low back pain were tested twice in 48 hours interval. The internal consistency of ODI-G was measured by cronbach’s alpha, and ODI-G data was used for that initial visit. The test-retest reliability of ODI-G was measured by Intraclass correlation coefficient (ICC) and in it the ratio between the ODI-G score obtained at the initial visit and at the second visit was used. Internal consistency is considered to be acceptable when cronbach’s alpha value exceeds 0.70. The ICC value ranges are as follows: 1 $=$ perfect reliability, 0.90 to 0.99 $=$ very high correlation, 0.70 to 0.89 $=$ high correlation, 050 to 0.69 $=$ moderate correlation and 0.26 to 0.49 $=$ low correlation.

2.4.2 Validity

Construct validity was measured by comparing Pearson correlations of ODI-G and RMDQ-G. Concurrent validity was measured by comparing Pearson correlations of ODI-G and VAS-P. The Pearson correlation (r) value ranges are as follows: 0.90 to 1 $=$ very strong correlation, 0.70 to 0.89 $=$ strong correlation, 0.40 to 0.69 $=$ moderate correlation, 0.20 to 0.39 $=$ weak correlation and 0.00 to 0.19 $=$ very weak correlation.

Figure 1.

A Cattel scree test was determined by number of extracted factors.

2.4.3 Factor analysis

Factor analysis is used to describe variability among observed and correlated variables. The factor structure of the ODI-G was measured by average of a factor analysis [5]. The number of extracted factors was determined by Cattel scree test (Fig. 1).

3. Data analysis

The data was tabulated in Microsoft EXCEL computer software and it was analyzed by using SPSS software. Descriptive statistics were utilized while explaining the sample. The results of the investigation were expressed as mean or standard deviation. The 95% confidence intervals were obtained.

Table 1
Descriptive statistics

Characteristics	Values
Subjects (n)	120
Male/Female (n)	41/79
Age in years – mean (SD)	43.13 (10.50)
Employed/Not employed	57/63
Pain duration (months) (SD)	2.63 (1.31)

4. Results

4.1 Descriptive statistics

The mean age of 120 subjects were 43.13 years respectively. The sample involved 79 female and 41 male participants with low back pain (Table 1).

The Gujarati version was translated successfully with minimum difficulty. In Section 4 (walking) of original English version distance were described in miles and yards, but Gujarati native speakers commonly use kilometers and feet. In translated version, miles and yards were converted into kilometers and feet by the permission of the author of ODI. The pilot testing indicated that the average time taken to complete the ODI-G was 5 minutes. The cognitive debriefing was done individually and it specified that the patients understood Gujarati questionnaire the same as the original would be understood. The pre-final version of the ODI-G was tested in 15 Gujarati speaking patients with low back pain and then it was accepted as the final version.

4.2 Reliability

A Cronbach alpha was obtained 0.96 which indicates excellent internal consistency reliability for translated ODI-G. Test-retest reliability of the ODI-G was obtained with an intra-class correlation coefficient (ICC) of 0.92 (0.89–0.94) with 95% confidence interval.

4.3 Validity

Construct validity was examined by comparing Pearson correlations(r) of ODI-G with RMDQ-G, and the ODI-G scores strongly correlated with the RMDQ-G scores $r=$ 0.76. Concurrent validity was measured by comparing Pearson correlations(r) of ODI-G with VAS-P, and it indicated moderate correlation $r=$ 0.50 between ODI-G and VAS-P.

Table 2
Factor analysis of principal components of ODI

Section	Item	Factor 1
8	Sex life	0.784
7	Sleeping	0.741
2	Personal care	0.721
9	Social life	0.693
3	Lifting	0.628
5	Sitting	0.617
4	Walking	0.574
10	Travelling	0.533
1	Pain intensity	0.506
6	Standing	0.460

ODI indicates Oswestry Disability Index.

4.4 Factor analysis

The factor analysis explained that the ODI scale was loaded on 1 factor. This factor described 33.77% of the total variance. Item factor loading are explained in Table 2.

5. Discussion

The aims of this study were to accomplish the translation and psychometric evaluation of the Oswestry Disability Index (ODI) version 2.1a. The results of this current study indicated the ODI-G as a reliable and valid outcome measure to evaluate disability in Gujarati-speaking nonspecific LBP patients. The Oswestry Disability Index was established in 1980, and it is condition-specific tool that is used in 200 published articles [16, 17]. It can be argued that condition-specific outcome measure, being the most commonly used item, is preferred by general outcome measure and the National Spine Network (NSN) to utilize the ODI over the RMDQ.

The general aim of using this type of outcome measure is to gain comparable information of the disability assessment as well as to evaluate the effect of different types of treatments. The analysis shows that among both outcome measures, the RMDQ is mostly used for patients with lesser limitation in function and the ODI is used for patients with greater limitation in function in terms of disability. The translation procedure was carried out as given by Mapi Research Institute, which involved forward translation, synthesis, back translation, expert committee review and the test of pre final version.

In Section 4 (Walking), the distance measure is mentioned in British Imperial System, but it is not used in Gujarati population. Patients were not able to judge the distance unit “mile”, so mile was replaced with kilometer and it became more understandable to the patients. With author’s permission, distance was translated from British Imperial System to metric system. So distance unit “kilometers” and “feet” were used instead of “mile” and “yards” as per Mapi research institute’s permission.

One of the experts proposed removal of Section 8 (Sex Life) as the question was not suitable in the target culture, but after a detailed discussion with Mapi institute, the expert was convinced with the importance of the Section 8. After expert committee review, all the experts gave their consent about the changes and revised the questionnaire.

The overall homogeneity of the questionnaire i.e., internal consistency was 0.96 of Gujarati ODI version 2.1a to assess disability in a patients with low back pain. It is similar to previously published research that is found in Chinese (0.90), German (0.90), Brazilian Portuguese (0.87), Colombia (0.86) and Italian (0.85). In other published studies, Strong et al. found Cronbach’s alpha value 0.71 by using version 1.0, Fisher and Johnson found Cronbach’s alpha value 0.76 by using version 2.0 and Kopec et al. found 0.87.

The test-retest reliability was calculated by intraclass Correlation Coefficient. The ICC value of Gujarati version for single measures is 0.92 that is similar to Brazilian Portuguese validation (0.99), Italian version (0.96) and Colombia version (0.94). In the original study, Fairbank et al. found ICC $=$ 0.99 ( $n=$ 22) at a 24 hr interval (Fairbank 1980), this may include a memory effect. In another published study, Kopec et al. found ICC $=$ 0.91, with 4 days interval, Gronblad et al., found ICC $=$ 0.83, with a 1-week interval, Japanese 0.93, with 1 day interval, Norwegian 0.88, with 2 days interval, Korean 0.91, with 2 days interval and Arabic 0.98, with 3 days interval.

For construct validity, we compared ODI-G and RMDQ-G and found correlation value $r=$ 0.76 showing strong correlation. It is similar to what was reported earlier for the Chinese ( $r=$ 0.76), Brazilian Portuguese ( $r=$ 0.81), Turkish ( $r=$ 0.81), Japanese ( $r=$ 0.78), Greek ( $r=$ 0.72), Iranian ( $r=$ 0.71), and Danish ( $r=$ 0.78).

For concurrent validity, we compared ODI-G and VAS-P and found correlation value $r=$ 0.50 showing moderate correlation. It is equal to what was reported for other translations such as Norwegian ( $r=$ 0.52), Korean ( $r=$ 0.42), Iranian ( $r=$ 0.54) and Brazilian Portuguese ( $r=$ 0.66).

The relationship between the variables was carried out by factor analysis. The factor analysis of the ODI-G showed that there was loading on 1 factor and this factor explaining 33.77% of the total variance. In previous published studies, Kelly et al. defined that their factors yielded 2 components. Walking, lifting and standing were related to the first factor. Pain intensity, personal care, sleeping, travelling and sitting were related to the second factor. Social life and sex life were related to both factors. Guermazi et al. defined their factor as static physical activities and dynamic physical activities.

6. Conclusion

The results indicated that the Oswestry Disability Index version 2.1a had been successfully translated from English to Gujarati. This study demonstrated excellent psychometric properties similar to the English version. The Gujarati ODI version 2.1a proved to be reliable and valid tool in nonspecific low back pain patients to assess disability. As the ODI is easy for the patient to administer and to score, both in clinical work and research, its use can now be recommended among Gujarati speaking patients.

Conflict of interest

None to report.

Footnotes

Acknowledgments

We are grateful all translators Mrs. Gayatri Desai, Dr. Dhruv Dave, Dr. Chirag Shah, and Dr. Rajesh Bharvad. The authors would like to thank Mr. V Prakash and Dr. Vikas Ratanpara for providing their valuable inputs in data analysis and editing manuscript.

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Reliability and validity study of the Gujarati version of the Oswestry Disability Index 2.1a

Abstract

BACKGROUND:

OBJECTIVE:

STUDY DESIGN:

METHODS:

RESULTS:

CONCLUSION:

Keywords

1. Introduction

2. Material and methods

2.1 Subjects

2.2 Translation and cross-cultural adaptation

2.4 Evaluation of psychometric properties

2.4.1 Reliability

2.4.2 Validity

3. Data analysis

Table 1 Descriptive statistics

4.1 Descriptive statistics

4.2 Reliability

4.3 Validity

Table 2 Factor analysis of principal components of ODI

5. Discussion

6. Conclusion

Conflict of interest

Footnotes

Acknowledgments

References

Table 1
Descriptive statistics

Table 2
Factor analysis of principal components of ODI