|Year : 2019 | Volume
| Issue : 2 | Page : 146-151
Development of the Marathi version of the Tampa scale of kinesiophobia 11: Cross-cultural adaptation, validity, and test–retest reliability in patients with low back pain
Kiran Harishchandra Satpute1, Parag S Ranade2, Toby M Hall3
1 Department of Kinesiotherapy and Physical Diagnosis; Department of Musculoskeletal Physiotherapy Smt. Kashibai Navale College of Physiotherapy, Pune, Maharashtra, India
2 Department of Neuro Physiotherapy, Smt. Kashibai Navale College of Physiotherapy, Pune, Maharashtra, India
3 School of Physiotherapy and Exercise Science, Curtin University, Perth, WA, Australia
|Date of Web Publication||23-Jul-2019|
Dr. Kiran Harishchandra Satpute
Department of Kinesiotherapy and Physical Diagnosis, Smt. Kashibai Navale College of Physiotherapy, Off Westerly Bypass, Narhe, Pune - 411 041, Maharashtra
Source of Support: None, Conflict of Interest: None
Background: The Tampa Scale of Kinesiophobia-11 (TSK-11) is used to assess fear of movement in patients with musculoskeletal dysfunction. However, for Indian-specific population, this scale is not available. We aim to cross-culturally adapt the TSK-11 into a regional Indian language (Marathi) and to assess its psychometric properties, validity, and reliability. Materials and Methods: The American Association of Orthopedic Surgeons guidelines were used for cross-cultural adaptation and psychometric testing. Psychometric testing included assessment of internal consistency (Cronbach's alpha) and test–retest repeatability (intraclass coefficient correlation), construct validity (Pearson correlation) by comparing the TSK-11 score to a visual analog scale (VAS) of confidence and pain, as well as the Marathi version of Oswestry Disability Index (ODI). Results: A total of 100 individuals with mean age of 38.9 years (Standard deviation = 11.34) completed the translated TSK-11 questionnaire on two occasions with an interval of one day. The translated Marathi version demonstrated excellent internal consistency (α = 0.85) and test–retest reliability (intraclass correlation coefficient = 0.93, confidence interval 95% = 0.90–0.95). There were moderate correlations between the total score of the TSK-11 questionnaire Marathi version and ODI score (r = 0.72), VAS pain score (r = 0.635), and VAS confidence score (r = −0.603). Receiver operating characteristics analysis indicated that the TSK-11 score was significantly able (P < 0.001) to discriminate the presence or absence of kinesiophobia. Conclusion: The Marathi version of TSK-11 is reliable and valid, with psychometric characteristics similar to the original English version. This assessment tool can be recommended to measure movement-related fear in future patient-oriented outcome studies for the Indian Marathi speaking population with low back pain.
Keywords: Low back pain, phobic disorders, reproducibility of results
|How to cite this article:|
Satpute KH, Ranade PS, Hall TM. Development of the Marathi version of the Tampa scale of kinesiophobia 11: Cross-cultural adaptation, validity, and test–retest reliability in patients with low back pain. Indian Spine J 2019;2:146-51
|How to cite this URL:|
Satpute KH, Ranade PS, Hall TM. Development of the Marathi version of the Tampa scale of kinesiophobia 11: Cross-cultural adaptation, validity, and test–retest reliability in patients with low back pain. Indian Spine J [serial online] 2019 [cited 2019 Dec 8];2:146-51. Available from: http://www.isjonline.com/text.asp?2019/2/2/146/263271
| Introduction|| |
In developing countries, the 1-year prevalence of low back pain (LBP) is reported to be ≥56%.,,, For the Indian population, the life time prevalence of LBP is said to range from 6.2% to 92%, and prevalence rates rise from the third decade of life to the sixth decade. As such, investigating LBP is of primary importance, as it causes great disability affecting personal and work life, and thereby affecting society at large with significant financial costs. For example, in the United States, the total cost of expenditure on LBP was estimated to be as much as $200 billion per year in 2001.
Usually, it is not possible to identify the specific cause for LBP in the majority of cases, and under such circumstances, it is described as being nonspecific. In such people, fear-avoidance beliefs are considered to be a risk factor for the development of persistent pain and subsequent disability, through activity limitation and maladaptive responses. Fear of movement is termed “kinesiophobia,” which can adversely influence outcomes during rehabilitation. Other psychosocial risk factors for the development of persistent pain include anxiety, hypervigilance, fear-avoidance beliefs, and emotional stress, and are suggested to be important for subgrouping people with chronic nonspecific LBP. These factors were considered to be the primary drivers in the development of chronic LBP apart from the persons work environment and lifestyle factors. In addition to the patient's own beliefs about movement and activity, fear-avoidance may also be influenced by the personal beliefs of the treating health professionals and can therefore have the potential to influence management.
Psychosocial risk factors play a contributory role in the transition from acute to chronic LBP. It is important to recognize these factors as the progression toward chronic pain can be avoided by addressing the identified risk factors at an early stage. Moreover, it has been suggested that for patients with chronic LBP, addressing psychosocial risk factors rather than by repeatedly prescribing inappropriate imaging, medications, or surgical interventions, can improve the patient's outcome.,, Škerström et al. examined the influence of kinesiophobia on the ability to work and found that when fear of movement was addressed as part of a multimodal rehabilitation program work ability was enhanced.
Pain-related fear, catastrophizing, and kinesiophobia are most commonly measured through self-report questionnaires, which are readily available to clinicians. Kinesiophobia can be assessed by the Tampa Scale of Kinesiophobia (TSK) questionnaire. This comprises 17 questions each scored using a 4-point Likert scale ranging from 1 (strongly disagree) to 4 (strongly agree). Two subcategories of the scale can be evaluated, somatic focus and activity avoidance. These components reflect the person's beliefs about their medical condition and the impact of physical activity on their injury/reinjury or exaggerated pain response. Woby et al. developed the TSK-11, a short form version of the TSK questionnaire which excludes four items (questions 4, 8, 12, and 16). These items were negatively worded and reverse scored, and two items (9 and 14) were not normally distributed, hence removed from the original questionnaire. The total score for the TSK-11 ranges from 11 to 44 with the later representing stronger fear-avoidance beliefs. The psychometric properties of the TSK-11 demonstrate good internal consistency (α = 0.79), test–retest reliability (ICC = 0.81), and validity similar to the original TSK with the advantage of brevity.
Previous reports have validated translated versions of the TSK and TSK-11 questionnaires for use in various languages across the globe.,,,,,, Although the Indian national language is Hindi, each of the 28 states have their own regional language. Marathi is the regional language of Maharashtra state which is the second largest state by population in India with a population of 11.24 million with Marathi spoken in other centers around the world. The TSK-11 questionnaire has not yet been translated into Marathi. For improved management of musculoskeletal disorders such as LBP, validated psychosocial screening tools need to be translated into the patient's specific language. Thus, the purpose of this study was to translate the TSK-11 questionnaire into Marathi language and assess the translated version's psychometric properties. The hypothesis was to assess the construct validity where the translated version of TSK-11 would have strong to moderate correlation with LBP-related disability.
| Materials and Methods|| |
This study was conducted for the development and cross-cultural adaptation of TSK-11 questionnaire Marathi version. The research study protocol was approved by the Ethics Committee of the institution.
For assessing psychometric properties, participants were patients with chronic LBP. These patients were diagnosed by orthopaedic surgeons and referred to Physiotherapy out patient department. At the time of enrolment, patients with chronic LBP with or without radiating leg pain were included if they could understand and comprehend written Marathi, were aged between 18–60 years and of both genders. The operational definition of chronic LBP was pain duration ≥3 months. Patients with acute and subacute LBP, recent lower quadrant surgery, fractures or infections, malignancies, upper motor neuron lesions, and those unable to understand the instructions necessary for completion of questionnaires were excluded from the study. A recent literature review and guidelines do not favor a specific sample size for validating a questionnaire, however, it was suggested that a minimum sample size of 100 patients should be considered.
Translation and cross-cultural adaptation
The process of cross-cultural adaptation of the TSK-11 questionnaire was carried out in accordance with the guidelines provided by the American Association of Orthopedic Surgeons (AAOS). The forward translation of the original English version TSK-11 questionnaire was carried out by two bilingual translators. The first translator was from a medical (Physiotherapy) background who was aware of the concept being measured, and the second translator was from a nonmedical background and blind to the concept being measured. The two translated versions were compared and analyzed to achieve the final version which was then back translated to an English version by two different professional translators who did not participate in the previous phase of forward translation. These translators were neither aware nor informed about the concept explored in the questionnaire. According to the guidelines, the back translators should have had source language (English) as their mother tongue and should also have been aware of the target language, that is, Marathi. This condition was not fulfilled as such expertise were not available at our research institute; therefore, Marathi speaking Indian translators with masters of art (English)/Ph.D qualifications in English were selected to translate the TSK-11 questionnaire back to English. From these two translated English versions, a final version was formed. The final synthesized English version was then compared with the original English version. All translators, as well as an orthopedic surgeon, and a senior physiotherapist were provided with the original and translated version of TSK-11 questionnaire and were asked to answer the following five questions.
- Do you think each item in the Marathi and original English versions have the same meaning? If not, then identify the item and provide suggestions
- Are there any grammatical errors? If yes, then identify and suggest corrections
- Do you think there are any words with multiple meanings? If yes, then suggest corrections
- Do you think the Marathi version measures the same concepts as the source language version? If not, then suggest changes
- Are there any idioms or colloquial terms?
Once all the members responded positively, to check for any errors in interpretation, a pilot study was carried out on a sample of 30 Marathi language speaking individuals recruited from the outpatient physiotherapy department. Based on their feedback, the final version of the questionnaire was developed and sent to expert committee members for the final approval.
Intrarater reliability was assessed by testing the individuals twice in a 24-h period. During this trial period, individuals did not receive any form of intervention until after the second reading was obtained. This time frame for retesting was chosen due to the highly fluctuating nature of LBP. Previously, it has been reported that it is difficult to recall the events associated with the fluctuating nature of LBP. Moreover, various studies assessing the reliability of self-reported questionnaires have also utilized similar time frames.,, Construct validity of this approved final version was assessed by calculating the correlation of TSK-11 questionnaire (Marathi) with LBP-related disability, pain intensity, and perceived movement confidence. To reduce bias, the TSK-11 questionnaire (Marathi) was administered by a therapist blind to the assessment of pain intensity, LBP-related disability, and lumbar active range of motion (AROM).
Disability associated with LBP was measured with the Marathi version of the Oswestry Disability Index (ODI). This version of the ODI has been shown to have excellent reliability, with an ICC for test–retest reliability of 0.943. A 10 cm visual analog scale (VAS) was used to measure pain intensity, ranging from 0 (no pain at all) to 10 (the worst imaginable pain). A VAS confidence scale was used to measure the level of confidence while performing spinal movements. This 10 cm scale was anchored with no confidence at all at its left end and full confidence at its right end. Lumbar spine AROM was measured with a bubble inclinometer, with participants in standing, feet placed shoulder-width apart. The average of three readings was considered as the recorded AROM. Lumbar flexion AROM was determined by the difference between two goniometric measurements, the first recorded at T12-L1, and the second recorded at S1-S2. Interrater and intrarater reliability for this measurement is good with ICC 0.83 (95% confidence interval [CI] = 0.64–0.92) and ICC 0.81 (95% CI = 0.60–0.91), respectively. The minimum detectable change for flexion AROM is 9°. The right and left lumbar lateral flexion was measured with the goniometer placed at T9–T12. Participants were asked to slide their hand down, the lateral side of the leg as far as possible without trunk and head deviation, while maintaining ground contact of both feet. Interrater and intrarater reliability for this measurement is reported to be good with ICC ranging from 0.83 to 0.88. In addition to these measurements, the time in minutes to complete the Marathi version of TSK-11 questionnaire was recorded from after giving the required instructions to the participant.
All data were analyzed using Statistical Package for Social Science (SPSS) (version 21, Chicago, IL, USA) with the level of significance for all statistical tests set at P ≤ 0.05. Descriptive statistics were used to describe the study population. The variables were tested for normal distribution with the Shapiro–Wilk test. Internal consistency of the scale was calculated with the Cronbach alpha. This reflects the extent to which items measure various aspects of the same characteristics and nothing else. The Cronbach alpha ranges from 0 to 1, therefore, a value that approaches 0.90 is high, and the scale can be considered reliable. Test and retest reliability was assessed by calculating ICCs. Pearson correlation coefficients were used to evaluate construct validity. These were determined for the correlation between the TSK-11 questionnaire score and VAS pain score, ODI score, and VAS confidence score. The discriminative ability of TSK-11 questionnaire (presence vs. absence of kinesiophobia, with cutoff score set at 50%) was tested using receiver operating characteristics (ROC) curve analysis.
| Results|| |
A total of 100 participants (67 males) with chronic LBP participated in the study, with the mean age of 38.9 (Standard deviation [SD] = 11.34) years, and the mean symptom duration of 10.6 (SD = 9.81) months. The individuals were all able to complete the questionnaire, and there were no missing values for any questions. Individuals were able to complete the questionnaire within 2.41 min after providing all the required instructions. The characteristics of individuals are presented in [Table 1].
Variability in the sample representation of different professions is presented in [Figure 1].
Despite the wide variation in the representation of professions, and therefore, the likely education level, the questionnaire was well accepted by all of the patients. The TSK-11 questionnaire Marathi version was shown to have excellent internal consistency indicated by the Cronbach coefficient of α = 0.85. ICCs for test–retest reliability was 0.93 with 95% CI ranging between 0.90 and 0.95, indicating excellent test–retest reliability.
The Pearson correlation coefficient comparing TSK-11 questionnaire with VAS pain score, ODI score, and VAS confidence indicate significant, but moderate correlations between the total score of the TSK-11 questionnaire Marathi version and ODI score (r = 0.72, P = 0.01), VAS pain score (r = 0.63, P = 0.01), and VAS confidence score (r = −0.60, P = 0.01).
The ROC analysis indicates that the TSK-11 questionnaire Marathi version was significantly able (P < 0.001) to discriminate the presence or absence of kinesiophobia as presented in [Figure 2].
In the context of this study, specificity (true-negative) refers to the number of individuals who were correctly identified by the translated Marathi TSK-11 questionnaire as not having fear of movement. Sensitivity (true-positive) refers to the number of individuals who were correctly identified by the translated Marathi TSK-11, as having movement fear. The area under the curve was 0.95 (95% CI 0.90-0.99) which indicates excellent accuracy to detect the presence of kinesiophobia using the TSK-11 Marathi version.
| Discussion|| |
The original TSK and TSK-11 questionnaires were constructed in the English language to measure movement-related fear confirming their clinical utility. This article reports on the cross-cultural adaptation, reliability, and validity of the translated Marathi version of TSK-11 questionnaire in people who suffer from chronic LBP, thus expanding the use of TSK-11 questionnaire for the Marathi speaking population of India. The results of this study indicate that the TSK-11 questionnaire was successfully translated into Marathi language without losing the psychometric properties of the original English version.
The guidelines as stated by the AAOS Committee were followed for cross-cultural adaptation with the exception of back translation. This involved a forward translation, an expert committee review, and the testing of the translated questionnaire before finalizing. The process of cross-cultural adaptation was mainly emphasizing meaning and content rather than word for word translation. The responses from all translators, orthopedic surgeon, and senior physiotherapist to the five questions regarding the accuracy of the translated questionnaire were utilized to refine the questionnaire before a pilot study. Based on the feedback from pilot testing of the preliminary translation, minor change was made with respect to ease of understanding the questions. Perhaps due to this rigorous translation process, the Marathi version of the TSK-11 questionnaire was easily understood and well accepted by all individuals with a 100% response rate. All questions and instructions were easily understood by all individuals in the study, and the questionnaire was completed in <3 min, excluding the instruction time.
The translated Marathi TSK-11 is homogeneous, that is, all the items assess different aspects of movement-related fear in patients with chronic LBP. This is supported with good internal consistency (α = 0.85) exceeding the previously reported internal consistency for the TSK-11 English version (α = 0.79) and Chinese version (α = 0.67). This higher value of Cronbach's alpha could be related to homogeneity in subject selection. The Italian (α = 0.77), Norwegian (α = 0.81) versions of TSK, and Portuguese version of TSK-13 demonstrated similar internal consistency (α = 0.82) as that of the Marathi TSK-11 version.
The translated Marathi version of the TSK-11 questionnaire also has less evidence of measurement errors with subsequent testing as it demonstrated excellent reliability (ICC = 0.93, 95% CI = 0.90–0.95). The original English version of the TSK-11 and other translated versions,, similarly demonstrates excellent test reliability in patients with chronic LBP. Vigatto et al., 2007 suggested that retest reliability of a self-reported questionnaire is influenced by the retesting time interval. Shorter retesting time in our study could have been responsible for the high levels of reliability.
The translated Marathi version of TSK-11 showed moderate correlation with the ODI score and VAS pain score. For disability (r = 0.72), the translated Marathi version was moderately correlated with the original English version which measured disability using the Roland Morris disability questionnaire (r = 0.51). The correlation coefficient with VAS pain score was not particularly strong (r = 0.635). However, the correlation was stronger than the original English version of the TSK-11, which showed only a fair relationship with pain (r = 0.27). The translated Marathi version of the TSK-11 showed a moderate negative correlation with the VAS confidence score (r = −0.603). A previous study used the VAS confidence score to assess the construct validity of TSK-13 which also showed a negative relationship between the VAS confidence level and movement-related fear (r = −0.772).
The ROC analysis showed that the Marathi version of TSK-11 was able to discriminate the presence or absence of kinesiophobia similar to the original English version. To the authors' knowledge, this Marathi version of the TSK-11 is the first questionnaire to assess kinesiophobia associated with chronic LBP to have been validated in the Marathi speaking population.
One of the strengths of our study is the considerable variability in the study sample with respect to individual's profession and education level, which is therefore more likely to be representative of the Maharashtra people in India. This suggests that the translated version can be utilized for patients with different socioeconomic status. Moreover, as the meaning of the items in the questionnaire was carefully translated and considered, the translated questionnaire should be applicable to the various regions in Maharashtra considering the minor variations in the written and spoken Marathi Language.
The major limitation of this study was the lack of a gold standard validated measure of fear-avoidance beliefs such as the fear-avoidance beliefs questionnaire or the pain catastrophizing scale. Unfortunately, these items are not available in the Marathi Language.
| Conclusion|| |
The results of this study indicate that the translated Marathi version of the TSK-11 questionnaire appears to be internally consistent, reliable, and valid for measuring the fear of movement. We recommend its use for future clinical studies to assess kinesiophobia among Marathi speaking patients with chronic LBP.
The authors would like to acknowledge MAPI for allowing us to use the Marathi version of the ODI. We also thank Mr. Shinde and Dr. Lokhande.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
Bener A, Dafeeah EE, Alnaqbi K. Prevalence and correlates of low back pain in primary care: What are the contributing factors in a rapidly developing country. Asian Spine J 2014;8:227-36.
Schneider S, Randoll D, Buchner M. Why do women have back pain more than men? A representative prevalence study in the federal republic of Germany. Clin J Pain 2006;22:738-47.
Louw QA, Morris LD, Grimmer-Somers K. The prevalence of low back pain in Africa: A systematic review. BMC Musculoskelet Disord 2007;8:105.
Hoy D, Toole MJ, Morgan D, Morgan C. Low back pain in rural Tibet. Lancet 2003;361:225-6.
Bindra S, Sinha AG, Benjamin AI. Epidemiology of low back pain in Indian population: A review. Int J Appl Basic Med Res 2015;5:166-79.
Meucci RD, Fassa AG, Faria NM. Prevalence of chronic low back pain: Systematic review. Rev Saude Publica 2015;49. pii: S0034-89102015000100408.
Katz JN. Lumbar disc disorders and low-back pain: Socioeconomic factors and consequences. J Bone Joint Surg Am 2006;88 Suppl 2:21-4.
O'Sullivan P. Diagnosis and classification of chronic low back pain disorders: Maladaptive movement and motor control impairments as underlying mechanism. Man Ther 2005;10:242-55.
Kori S, Miller R, Todd D. Kinesiophobia: A new view of chronic pain behavior. Pain Manag 1990;3:35-43.
George SZ, Fritz JM, McNeil DW. Fear-avoidance beliefs as measured by the fear-avoidance beliefs questionnaire: Change in fear-avoidance beliefs questionnaire is predictive of change in self-report of disability and pain intensity for patients with acute low back pain. Clin J Pain 2006;22:197-203.
Waddell G, editor. The biopsychosocial model. In: The Back Pain Revolution. Edinburgh: Churchill Livingston; 2004. p. 265-82.
Houben RM, Leeuw M, Vlaeyen JW, Goubert L, Picavet HS. Fear of movement/injury in the general population: Factor structure and psychometric properties of an adapted version of the Tampa scale for kinesiophobia. J Behav Med 2005;28:415-24.
Linton SJ, Vlaeyen J, Ostelo R. The back pain beliefs of health care providers: Are we fear-avoidant? J Occup Rehabil 2002;12:223-32.
Pincus T, Burton AK, Vogel S, Field AP. A systematic review of psychological factors as predictors of chronicity/disability in prospective cohorts of low back pain. Spine (Phila Pa 1976) 2002;27:E109-20.
Swinkels-Meewisse IE, Roelofs J, Schouten EG, Verbeek AL, Oostendorp RA, Vlaeyen JW, et al.
Fear of movement/(re) injury predicting chronic disabling low back pain: A prospective inception cohort study. Spine (Phila Pa 1976) 2006;31:658-64.
George SZ, Fritz JM, Bialosky JE, Donald DA. The effect of a fear-avoidance-based physical therapy intervention for patients with acute low back pain: Results of a randomized clinical trial. Spine (Phila Pa 1976) 2003;28:2551-60.
Klaber Moffett JA, Carr J, Howarth E. High fear-avoiders of physical activity benefit from an exercise program for patients with back pain. Spine (Phila Pa 1976) 2004;29:1167-72.
Deyo RA, Mirza SK, Turner JA, Martin BI. Overtreating chronic back pain: Time to back off? J Am Board Fam Med 2009;22:62-8.
Škerström ML, Grimby-Ekman A, Lundberg M. Work ability is influenced by kinesiophobia among patients with persistent pain. Physiother Theory Pract 2017;33:634-43.
Turk DC, Wilson HD. Fear of pain as a prognostic factor in chronic pain: Conceptual models, assessment, and treatment implications. Curr Pain Headache Rep 2010;14:88-95.
Roelofs J, Goubert L, Peters ML, Vlaeyen JW, Crombez G. The Tampa scale for kinesiophobia: Further examination of psychometric properties in patients with chronic low back pain and fibromyalgia. Eur J Pain 2004;8:495-502.
Woby SR, Roach NK, Urmston M, Watson PJ. Psychometric properties of the TSK-11: A shortened version of the Tampa scale for kinesiophobia. Pain 2005;117:137-44.
Lundberg M, Styf J, Carlsson S. A psychometric evaluation of the Tampa scale for kinesiophobia-from a physiotherapeutic perspective. Physiother Theory Pract 2004;20:121-33.
Bunketorp L, Carlsson J, Kowalski J, Stener-Victorin E. Evaluating the reliability of multi-item scales: A non-parametric approach to the ordered categorical structure of data collected with the Swedish version of the Tampa scale for kinesiophobia and the self-efficacy scale. J Rehabil Med 2005;37:330-4.
de Souza FS, Marinho Cda S, Siqueira FB, Maher CG, Costa LO. Psychometric testing confirms that the Brazilian-Portuguese adaptations, the original versions of the fear-avoidance beliefs questionnaire, and the Tampa scale of kinesiophobia have similar measurement properties. Spine (Phila Pa 1976) 2008;33:1028-33.
Haugen AJ, Grøvle L, Keller A, Grotle M. Cross-cultural adaptation and validation of the Norwegian version of the Tampa scale for kinesiophobia. Spine (Phila Pa 1976) 2008;33:E595-601.
Wong WS, Kwok HY, Luk KD, Chow YF, Mak KH, Tam BK, et al.
Fear of movement/(re) injury in Chinese patients with chronic pain: Factorial validity of the Chinese version of the Tampa scale for kinesiophobia. J Rehabil Med 2010;42:620-9.
Monticone M, Giorgi I, Baiardi P, Barbieri M, Rocca B, Bonezzi C, et al.
Development of the Italian version of the Tampa scale of kinesiophobia (TSK-I): Cross-cultural adaptation, factor analysis, reliability, and validity. Spine (Phila Pa 1976) 2010;35:1241-6.
Cordeiro N, Pezarat-Correia P, Gil J, Cabri J. Portuguese language version of the Tampa scale for kinesiophobia [13 Items]. J Musculoskelet Pain 2013;21:58-63.
Deo A. Economic Survey of Maharashtra; 2013-14.
Anthoine E, Moret L, Regnault A, Sébille V, Hardouin JB. Sample size used to validate a scale: A review of publications on newly-developed patient reported outcomes measures. Health Qual Life Outcomes 2014;12:176.
Tsang S, Royse CF, Terkawi AS. Guidelines for developing, translating, and validating a questionnaire in perioperative and pain medicine. Saudi J Anaesth 2017;11:S80-9.
Beaton DE, Bombardier C, Guillemin F, Ferraz MB. Guidelines for the process of cross-cultural adaptation of self-report measures. Spine (Phila Pa 1976) 2000;25:3186-91.
Stone AA, Shiffman S. Capturing momentary, self-report data: A proposal for reporting guidelines. Ann Behav Med 2002;24:236-43.
Vigatto R, Alexandre NM, Correa Filho HR. Development of a Brazilian Portuguese version of the Oswestry disability index: Cross-cultural adaptation, reliability, and validity. Spine (Phila Pa 1976) 2007;32:481-6.
Jeldi AJ, Aseer AL, Dhandapani AG, Roach KE. Cross-cultural adaptation, reliability and validity of the Indian (Tamil) version of the shoulder pain and disability index. Hong Kong Physiother J 2012;30:99-104.
Joshi VD, Raiturker PP, Kulkarni AA. Validity and reliability of English and Marathi Oswestry disability index (version 2.1a) in Indian population. Spine (Phila Pa 1976) 2013;38:E662-8.
Kolber MJ, Pizzini M, Robinson A, Yanez D, Hanney WJ. The reliability and concurrent validity of measurements used to quantify lumbar spine mobility: An analysis of an iphone® application and gravity based inclinometry. Int J Sports Phys Ther 2013;8:129-37.
Portney, Watkins. Foundations of Clinical Research: Applications to Practice. New Jersey: Pearson Prentice Hall; 2015.
Fawcett T. An introduction to ROC analysis. Pattern Recognit Lett 2006;27:861-74.
[Figure 1], [Figure 2]