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 Table of Contents  
Year : 2017  |  Volume : 24  |  Issue : 2  |  Page : 103-106

Reliability and validity of the Yoruba version of the Oswestry disability index

1 Department of Physiotherapy, College of Medicine, University of Lagos, Lagos, Nigeria
2 Department of Physiotherapy, National Orthopedic Hospital, Lagos, Nigeria

Date of Web Publication24-Jul-2017

Correspondence Address:
Ayoola Ibifubara Aiyegbusi
Department of Physiotherapy, College of Medicine, University of Lagos, Lagos
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/npmj.npmj_26_17

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Context: Low back pain (LBP) is a major cause of disability, and the Oswestry Disability Index (ODI) is a validated assessment tool for evaluating disability in LBP patients. Cross-cultural adaptation of the ODI is important because not all populations are proficient in English. The Yoruba language is an indigenous language spoken by 40 million people in the Western part of Nigeria and some countries in West Africa and Latin America. Currently, no validated Yoruba version of ODI is available. Aims: The aim of the study was to translate, culturally adapt and validate the ODI in Yoruba language for participants with LBP. Subjects and Methods: The ODI was translated into Yoruba, and this translated version was analysed in terms of semantics and linguistics. Then, the Yoruba version was translated back into English and both versions administered to 160 participants with LBP. The internal consistency using Cronbach's alpha coefficient, criterion validity and test–retest reliability were assessed using Spearman's rank correlation with significance set at P< 0.05. The inter-rater reliability was evaluated by two different observers and the intra-rater reliability was determined by the same observer, a week apart. Results: The internal consistency of the Yoruba ODI with Cronbach's alpha was 0.97, the intrarater reliability yielded an intraclass correlation coefficient of 0.93 and criterion validity assessed using Spearman's rank correlation was r = 0.92 for highest score and 0.63 for lowest score. Conclusion: The Yoruba ODI is a reliable and valid tool for assessing functional disability in LBP patients.

Keywords: Low back pain, Oswestry Disability Index, reliability, validity, Yoruba translation

How to cite this article:
Aiyegbusi AI, Akodu AK, Agbede EO. Reliability and validity of the Yoruba version of the Oswestry disability index. Niger Postgrad Med J 2017;24:103-6

How to cite this URL:
Aiyegbusi AI, Akodu AK, Agbede EO. Reliability and validity of the Yoruba version of the Oswestry disability index. Niger Postgrad Med J [serial online] 2017 [cited 2020 Jul 13];24:103-6. Available from: http://www.npmj.org/text.asp?2017/24/2/103/211456

  Introduction Top

Low back pain (LBP) which is considered to be the leading cause of activity limitation, and work absenteeism all over the world is classified as acute, subchronic, or chronic with symptoms usually improving spontaneously within a few weeks and with 40%–90% of people completely improved by 6 weeks. LBP is the highest contributor to disability in the world and is primarily treated by physician and physiotherapist.[1],[2],[3] In LBP, disability is often interpreted as pain interfering with activities such as mobility, dressing, sitting and standing and patients often give this information by completing disability questionnaires which are more consistent and reliable than interviews because they present the question exactly the same way patient feel.[4]

Several outcome measures have been used by clinicians to quantify patients' level of disability following LBP, and the commonly used ones are the Roland Morris Disability Questionnaire, Quebec Pain Disability Scale and Oswestry Disability Index (ODI).[5] Practicality, precision, reliability, validity, responsiveness and ability to detect a change in a specific condition are important properties of an outcome measure.[6] The ODI outcome measure was developed in 1976, and it is one of the most popular outcome measures throughout the world for evaluation of disability in LBP.[7] Based on psychometric evaluation as well as feasibility considerations, it has been suggested that the ODI is arguably the best assessment for the level of disability caused by LBP.[8]

Several studies have been carried out in different countries on translation and validation of ODI into indigenous languages in patients with LBP. A study was conducted in Tamil (ODI-T) with cross-cultural adaptation and evaluation of reliability and validity and the results demonstrated the preliminary evidence that the ODI-T is a reliable and valid measure to assess disability in Tamil-speaking LBP patients with a high internal consistency value (0.92) which was consistent with the original English version (0.87).[9] Observed test–retest reliability value was high (intraclass correlation coefficient [ICC] = 0.92) which was comparable to the ICC reported for the original version (0.91), and this clearly supports the reproducibility of the results of the ODI-T.[10]

The ODI has been cross-culturally adapted, validated and translated into about 12 languages because of its popularity which is evident.[11] Cross-cultural adaptation of the already known outcome measures is important because not all populations are proficient in English; thus, exclusion of non-English-speaking individuals could lead to systematic bias in studies of healthcare quality. Several studies in the past have used ODI in the assessment of functional disabilities of patients; however, there has been a problem of language difficulty. The Yoruba language is an indigenous language spoken by over 40 million people in the Western and North Central Nigeria as well as Southern and Central Benin Republic.[12] In addition, there are Yoruba communities in such countries as Cuba, Saint Lucia, Jamaica, Brazil, Grenada, Trinidad and Tobago, amongst others.[13] Yoruba, being the language spoken by one of the largest ethnic groups in the world, is imperative to design an ODI in this indigenous language. This study was, therefore, designed to translate the ODI questionnaire into Yoruba language and to evaluate the Yoruba version of ODI for validity and test–retest reliability in patients with LBP. The findings of this study may present the ODI-Yoruba as an effective outcome measure tool in clinical practice for Yoruba-speaking patients who do not understand English.

  Subjects and Methods Top

Subject selection

A total of 212 participants with LBP were recruited for this study, but 160 participants (110 females and 50 males) (LBP) completed the study. They were participants who presented with LBP and were referred to the physiotherapy clinics of the study centres from where they were recruited. For the purpose of this study, LBP is defined as pain that occurs in an area between the 12th rib and the inferior gluteal folds with or without leg pain.[14] Participants with LBP who could read and write both English and Yoruba were included in the study whereas participants with cognitive disorders were excluded from the study.

Sample size determination

The sample size was determined using the Cohen's formula (Cohen, 1992)

Sample formula

n = N (Z1 + Z2)2/ES 2

Where n = minimum sample size,

N = number of groups

Z1 = alpha (coefficient interval at <0.05)

Z2 = beta (coefficient interval = 1−α = 1 − 0.05 = 0.95)

ES = Efficient size (using a small effect size of 0.20)

n = 1 (1.96 + 0.95)2/(0.20)2

n = 212.


Oswestry disability Index questionnaire

The ODI questionnaire is a self-administered questionnaire which is divided into ten sections which can be used to assess the disability level of the patients. The sections have to do with intensity of pain, lifting, ability to care for oneself, ability to walk, ability to sit, sexual function, ability to stand, social sleep quality and ability to travel. Each section is scored on 0–5 scale with five representing the greatest disability. The index is calculated by dividing the total summed score by the total possible score, which is then multiplied by 100 and expressed as a percentage. Thus, for every question not answered, the denominator is reduced by five. If a patient marks more than one statement in a question, the highest scoring statement is recorded as a true indication of disability.[11]


This study was an observational study to validate a scale and ethical approval for this research was sought and obtained from the Institutional Health Research and Ethics Committee with registration number: ADM/DCST/HREC/APP/1028 (July 14, 2016). Informed consent was sought and obtained from the participants before the commencement of the study with confidentiality of all information obtained from the patients assured.

Research protocol

Participants with LBP were drawn from the outpatient units of the Physiotherapy Departments of the Lagos University Teaching Hospital and the National Orthopaedic Hospital, Igbobi, Lagos. Purposive sampling technique was used in the recruitment of participants for the study. Two hundred and twelve participants gave their consent to participate in the study, but 180 participants met the inclusion criteria whereas 32 were ineligible and therefore excluded from the study. One hundred and sixty participants completed this study whereas twenty participants withdrew due to lack of transport and illness.

Procedure for data collection

The original English version of the ODI was translated into Yoruba language by two experts in linguistics both in English and Yoruba at the Department of Linguistic, African and Asian Studies and then translated back to English language. The translated Yoruba language version of the ODI was then reviewed by some physiotherapists who are proficient in English and Yoruba. The procedure of this study was explained to the participants and consent to participate was sought. Participants with LBP that met the inclusion criteria filled the English and Yoruba versions of the ODI questionnaire. The translated Yoruba language version was self-administered first to the participants, followed by the English version at baseline. The Yoruba translated version was self-administered again to participants on their next appointments which was a week interval from baseline.[15]

Data analysis

Data were analysed using Statistical Package for the Social Sciences (Version 21) IBM SPSS Statistics for Windows, Version 21.0. (Armonk, NY: IBM Corp.) and summarised using descriptive statistics of mean and standard deviation. Spearman's rho was used to determine the relationship between the scores obtained from Yoruba translated version of ODI assessed on the two occasions and also to determine the correlation between scores on the English and Yoruba version of ODI questionnaire and reliability with ICC. Level of significance was set at P< 0.05.

  Results Top

A total of 160 participated in this study with the mean age of the participants being 41.63 ± 9.71. One hundred and ten (68.75%) of the respondents were females while fifty (31.25%) were males. One hundred and six (62.5%) of the respondents had a tertiary education while 44 (33.7%) attended secondary school. About 44 (33.75%) respondents' occupations were homemakers, 26 (16.25%) were into business, 46 (28.75%) were civil servants, 18 (11.25%) were students whereas 16 (10%) were others.

The Yoruba and English ODI questionnaires were assessed using Spearman's rank correlation, and the results show a significant positive correlation in all the activities with 'enduring pain' having the highest correlation (0.92) whereas 'carrying items' had the lowest correlation (0.63) [Table 1].
Table 1: Spearman's rank correlation between Yoruba and English Oswestry Disability Index questionnaires

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The reliability of the Yoruba and English versions of the ODI was assessed at baseline using Cronbach's alpha to determine the internal consistency of the ODI questionnaire, and this was found to be significant (P = 0.001) at 0.95 for both Yoruba and English version of ODI. Test–retest reliability of the Yoruba version was assessed by correlating the scores obtained on two consecutive administration of the Yoruba ODI, and all the domains were seen to be significant [Table 2].
Table 2: Test-retest reliability of Yoruba translated version of Oswestry Disability Index questionnaire

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The reliability of the Yoruba ODI questionnaire was assessed at baseline and a week after using Cronbach's alpha coefficient to determine the internal consistency. The Cronbach's alpha coefficient yielded 0.97 and was significant at P= 0.001 which indicated very good internal consistency of the Yoruba ODI questionnaire. The intra-rater reliability of ODI was assessed to measure agreement between the Yoruba version of ODI administered at baseline and a week after using the ICC. The result of the average measure ICC was 0.93 confidence level of 95% confidence interval (0.87–0.95) [Table 3].
Table 3: Measurement of intra.rater reliability of Yoruba Oswestry Disability Index questionnaire

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  Discussion Top

This study was designed to translate and validate the Yoruba version of ODI in participants with LBP. All the questions were 100% completed with the exception of sex life which constitute about 43.8% at baseline between Yoruba and English ODI questionnaire and 31.3% a week after (Yoruba ODI questionnaire), possibly because people express reservations in this part of the world about discussing their sex life publicly. The findings from this study showed that there were significant correlation scores in both Yoruba and English ODI questionnaires at baseline, which is an indication that the questionnaires exactly presented the way the patients felt.[4]

We found significant changes in the scores obtained from the correlation in the test–retest reliability when compared to the correlation scores at baseline between the Yoruba and English ODI and a week after which is an indication that the outcome measures were able to detect changes in all the domains, and this is in agreement with the report that the responsiveness and ability to detect changes in a specific domain are an important properties of an outcome measure, it also shows that the translated version of ODI is a reliable tool and stable instrument for outcome measures.[6] The result of this study reveals the Cronbach's alpha to be 0.95 at baseline between the Yoruba and English ODI questionnaire, whereas it was 0.97 in the Yoruba ODI questionnaire. Shuttleworth [16] recommends a Cronbach's alpha of 0.70 minimum and above to be an acceptable reliability score. The Cronbach's alpha 0.97 for Yoruba questionnaire demonstrated very good internal consistency which was even higher than the original English version of 0.8.[9] This agrees with the finding of a similar study on the translation and validation of ODI in Italy which falls within the recommended Cronbach's alpha range of 0.85.[17] This value is higher than the result of the study by Vigatto et al.,[18] on translation and validation of ODI in Portuguese Brazilian which was 0.87. The result of the Cronbach's alpha in some other languages was found to be higher than the original English version in some countries where the ODI was translated and validated in Tamil: 0.92,[19] Chinese: 0.90,[20] and German: 0.90.[21]

The result from this study shows the intra-rater reliability with ICC yielding 0.93 between the Yoruba ODI administered first at baseline and a week after which falls in almost perfect agreement with the Columbia inter-rater reliability (ICC = 0.94) and intra-rater reliability (ICC = 0.95).[22] This could be attributed to the fact that the respondents were able to properly relate the levels of their functional disability to the questionnaires.

One limitation of this study was that some of the participants did not complete the study which affected the calculated sample size. However, the results of this study suggest that the translated Yoruba version of the ODI is a reliable and valid instrument for the measurement of disability amongst Yoruba-speaking patients with LBP.

Based on the findings of this study, it is recommended that the Yoruba ODI is used as an outcome tool for the assessment of disability in Yoruba-speaking patient with LBP. Further studies could be carried out to assess the reliability and validity of ODI in other Nigerian languages in a larger population.

Financial support and sponsorship

This study was funded by the authors.

Conflicts of interest

There are no conflicts of interest.

  References Top

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Monticone M, Baiardi P, Ferrari S, Foti C, Mugnai R, Pillastrini P, et al. Development of the Italian version of the Oswestry disability index (ODI-I): A cross-cultural adaptation, reliability, and validity study. Spine (Phila Pa 1976) 2009;34:2090-5.  Back to cited text no. 17
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Mannion AF, Junge A, Fairbank JC. Development of a German version disability index. Part 1. Eur Spine J 2006;15:55-65.  Back to cited text no. 21
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  [Table 1], [Table 2], [Table 3]


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