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RESEARCH PAPER. Reliability and validity of the Hindi version of the Neck Pain and .... NPAD, adapt it for usage in the Hindi language, and test its reliability ...
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Disability & Rehabilitation

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Reliability and validity of the Hindi version of the Neck Pain and Disability Scale in cervical radiculopathy patients a

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Shabnam Agarwal ; Garry T. Allison ; Ajay Agarwal ; Kevin P. Singer a Belle Vue Clinic. Kolkata. India b The Centre for Musculoskeletal Studies, The University of Western Australia. Perth. Western Australia c Calcutta Medical Research Institute. Kolkata. India To link to this article: DOI: 10.1080/09638280600641467 URL: http://dx.doi.org/10.1080/09638280600641467

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Disability and Rehabilitation, November 2006; 28(22): 1405 – 1412

RESEARCH PAPER

Reliability and validity of the Hindi version of the Neck Pain and Disability Scale in cervical radiculopathy patients Downloaded By: [informa internal users] At: 08:05 19 February 2007

SHABNAM AGARWAL1, GARRY T. ALLISON2, AJAY AGARWAL3 & KEVIN P. SINGER2 1

Belle Vue Clinic, Kolkata, India, 2The Centre for Musculoskeletal Studies, The University of Western Australia, Perth, Western Australia, and 3Calcutta Medical Research Institute, Kolkata, India Accepted February 2006

Abstract Purpose. To assess the reliability and validity of the Neck Pain and Disability Scale (NPAD) translated into Hindi. Method. Following a pilot study to ascertain uncertainties with existing terminology in the NPAD scale, a cervical radiculopathy patient cohort (n ¼ 63) was assessed with the translated NPAD. Reliability was assessed by regression analysis for test-retest and by item-factor and factor-total score correlations. Face validity was compared in a cross-sectional design study with an asymptomatic group (n ¼ 38). Convergent and divergent validity were investigated by correlating the NPAD scores with the Numerical Pain Rating Scale (NPRS) for neck and arm pain, and 10 cm long VAS Activity and VAS Depression scales. Results. ICC values for test-retest NPAD total and factor scores were 40.92 and R2 values 40.912. Pearson product moment correlation of item vs. factor scores varied from 0.17 – 0.91 and for factor vs. total scores 0.72 – 0.91. Differences in NPAD scores between the patient and the asymptomatic group were significant (t ¼ 30.90, p 5 0.05). Convergent validity was explained when Factor 2 (minus item 20) was correlated (r ¼ 0.67) with NPRS maximum value scores. Divergent validity was illustrated by low correlation with VAS Activity (r ¼ 0.15) and negative correlation with VAS Depression (r ¼ 70.80) scores. Conclusion. Based on the results of this study, the Hindi version of the NPAD is a reliable and valid instrument for the assessment of pain and disability in cervical radiculopathy patients.

Keywords: Neck pain, cervical spine, Hindi, NPAD, Indian

Introduction Cervical radiculopathy clinically presents as neck, shoulder or arm pain with neurological involvement. Valid and reliable tests are keystones in clinical research and are essential for the purpose of research, documentation of treatment efficacy and outcomes. The NPAD [1] scale was developed as a self-reported questionnaire and measures the intensity of pain, its interference with vocational, recreational, social and functional aspects of living, and analyses the presence and extent of associated emotional factors. The psychometric properties of the NPAD and other regional scales like the Neck Disability Index (NDI) [2] and the Northwick Park Questionnaire (NPQ) [3] have been evaluated.

The suggested advantages of the NPAD over the other two questionnaires are that it is multi-dimensional and the questions have greater applicability [4]. The NPAD was developed based on the Million Visual Analogue Scale (VAS) template [5] and consists of 20 items/questions. Each question has a 10 cm visual analogue scale graded from 0 (normal function) to 5 (worst possible situation due to pain). The total score is a maximum of 100. Solid vertical lines indicate whole points (0 – 5), vertical grids placed in between two solid lines represent half points, and if a marking is made between the solid line and the vertical grid then one quarter is added to the score. In two separate studies [1,6] which analysed the 20 items, the face, criterion validity,

Correspondence: Shabnam Agarwal, Belle Vue Clinic, 9 Dr UN Brahmachari Street, Kolkata 700 017, India. Tel: þ91 33 22298433. Fax: þ91 33 22806925. E-mail: [email protected]; [email protected] ISSN 0963-8288 print/ISSN 1464-5165 online ª 2006 Informa UK Ltd. DOI: 10.1080/09638280600641467

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construct validity, and test-retest reliability was established. Pain and disability scales can be indigenously created or translated from existing ones. The NPAD scale has been successfully translated from English to French [7] and Turkish [8], and reliability and validity established for the translated versions. This process allows comparison of results of clinical research trials across countries because of usage of the same scale, albeit in different languages. Hindi is the national language of India. To date, domestic development of pain and disability scales in Hindi is lacking because evaluation is based upon traditional methods of clinical signs and symptoms and probably a sizeable population has a basic knowledge of the English language. The concept of functional measurement is noticeably different from conventional measures of signs and symptoms, because the former evaluates the impact of the condition on the individual’s lifestyle and is dependent upon age, profession and the ability to cope with the problem [4]. Assessment of the impact that a degenerative condition of the neck has on a patient’s life is important during clinical follow-up and for treatment outcome measures following medical and surgical intervention [4]. Pain is acknowledged to be a complex perceptual experience with a number of underlying factors that include sensory, affective, and intensity dimensions [6]. The four characteristics of the NPAD scores have been identified as, neck problems (factor 1), pain intensity (factor 2), the effect of neck pain on emotion and cognition (factor 3) and the degree to which neck pain interfered with life activities (factor 4) [1]. The NPAD has been used to assess patients with neck pain of traumatic and nontraumatic origin [6], chronic neck pain [1,7,8] and has been used in a longitudinal study to test the treatment efficacy of botulinum toxin injections in chronic neck pain [6]. The French version of the NPAD was tested for sensitivity to change in clinical status in neck disorder patients over a period of 11 months [9]. Cervical radiculopathy is a complex condition where nerve root irritation in the cervical spine may result from trauma or in pre-existing cervical spondylosis. Nerve roots may be involved unilaterally or bilaterally which results in a mixture of pain in the neck, arm and varying degree of motor and sensory deficits [9]. The NPAD to date has not been used to evaluate patients with cervical radiculopathy nor in the context of studies undertaken in India. The present study sought to translate the NPAD, adapt it for usage in the Hindi language, and test its reliability and validity in a clinical cohort with cervical radiculopathy in an Indian clinical setting.

Materials and method Pilot study Adaptations in the English as well as the translated version were made based on a pilot study using the original English version, involving 15 patients. Alterations and explanations were incorporated in the original and the translated version for items which patients in this study did not understand or marked ‘do not do’. This minimized missing responses and increased acceptability and comprehension. . The term ‘pain’ was replaced by ‘neck/arm pain’. . ‘Social activities’ and ‘recreational activities’ are not clearly distinctive. The term recreation is not an exclusive term and often overlaps with social activities. These activities were elucidated with examples. Examples for recreational activities were ‘playing games, watching films, pursuing hobbies etc.’ and for social activities, ‘meeting relatives and friends, attending functions etc.’. . Item 7 about ‘driving or riding in a car’ was altered by adding other modes of transport, namely, bus, two-wheeler, and rickshaw. . The terminology ‘overhead activities’ was not understood and was elaborated with examples, ‘reaching for top shelves in cabinets, hanging clothes, etc.’. . The half and quarter markings on each VAS scale of the NPAD were deleted. . In item 20, ‘pain pills’ was changed to ‘pain medicines’. Translation The NPAD (Annexure 1) was translated by the forward and backward procedure [7,9]. Three pairs of bilingual professionals, two bilingual patients and one professional translator were involved in this process. The three pairs of professionals were two neurosurgeons, two orthopaedic surgeons and two physiotherapists who treat patients with neck pain in their routine clinical practice. All were familiar with the terminology and expressions used for describing pain and disability. The patients included those diagnosed with chronic radiculopathy and could associate the scale with symptoms they had. One individual of each pair translated the scale from English to Hindi once. The goal was to retain the concept of the original scale using culturally and clinically appropriate expressions [7,9]. The other pair then translated the scale back to English and this highlighted errors in translation that may have occurred by the first translator. It was expected that

Reliability of the Hindi version of the NPAD

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involvement of eight individuals would identify all possible translation discrepancies. Complex problems of language, relationship between language and expressions of pain, cultural diversity, conceptual equivalences and vocabulary differences were highlighted by this technique and modifications were made based on this [8,9]. The final consensus was arrived at by scrutinizing the translations by the expert linguist and the researcher. Participants Patients (n ¼ 64, 40 men; 24 women, mean age 41 + 11.15 years), who were referred to the Physiotherapy outpatients (OPD) in two private hospitals of Kolkata, from July 2003 to December 2004, were included in this study if they met the following inclusion criteria: Diagnosis of cervical radiculopathy by an experienced spinal surgeon and clinical assessment by an experienced physiotherapist. The diagnosis supported by neuroradiological investigations: X-ray (frontal and oblique views; sagittal views in neutral, flexion and extension) and MRI, routinely performed for confirmation of clinical diagnosis. Both T1 and T2 MRI images were screened for curvature, canal and neural foramen diameter, osteophytes and disc degeneration. Exclusion criteria used for this study: Cervical spine tumour, trauma or prior surgery, spinal deformities, arthritis, mental illness, obesity, cerebro-vascular accident, myocardial infarction, chronic lung or renal diseases and recent pregnancy. A further 38 asymptomatic individuals (31 men; 7 women, mean age 43 years, range 25 – 67) were recruited from hospital staff which comprised professional, clerical and manual staff as well as persons accompanying patients. Participants were encouraged to read the questionnaire prior to marking. Clarifications could be confirmed by asking the researcher only. The questionnaire was marked on two consecutive visits by the patients to the Physiotherapy OPD. Testing the scales The total time needed to complete the questionnaire was recorded. Reliability. Test-retest reliability was examined by repeat measurements on two consecutive days. Out of 64 patients with cervical radiculopathy, only 57 (36 men, 21 women) could be measured twice. Reasons included non-attendance and change in clinical status. The difference in clinical status between the two days was assessed with a 10 cm VAS pain scale. If the patient VAS pain score changed more than 2 cm then they were excluded

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from the reliability testing analysis. Five delusive items were placed in the questionnaire [7] and the question order was changed for repeat measurements. The item-factor correlation and factor-total correlation of the NPAD were calculated to ascertain if item scores within a factor correlated to the relevant factor score and if factor scores correlated with the total score. Validity. Face validity is a subjective assessment of whether the measure appears relevant to the ones to be measured. Face validity was assessed by asking one question to each of the patients, ‘Do you think this scale is relevant to your condition.’ The answer was noted as ‘yes’ or ‘no’ and was also evaluated by comparing the NPAD scores of the cervical radiculopathy group vs. the asymptomatic group. Construct validity is tested by verifying theoretical relationships between scale scores and external criteria. Convergent and divergent validity are the basis of construct validity. The Numerical Pain Rating Scale (NPRS) [10] for neck pain and arm pain was correlated with factor 2 of the NPAD to test convergent validity. Divergent validity scores were assessed by correlating factor 3 of the NPAD with a 10 cm VAS Depression tested by the question ‘Does your pain make you feel depressed?’; ‘0’ indicated complete depression and ‘10’ no depression at all. The activity question correlated with factor 4 of the NPAD asked ‘Does your neck pain affect activities like stair climbing, squat to stand?’ On a 10 cm VAS Activity the score ‘0’ implied no activity was possible and ‘10’ full activity. The VAS is simple to use, requires minimal terminology and was explained to the patients. Statistical analysis The difference in VAS scores for between-day measurements to detect a change in clinical status in the patient group was calculated with a paired t-test. Reliability. Test- retest measurements were compared using the Intra-class Correlation Coefficient (ICC2,1) for total and factor scores. A linear regression analysis was used to compare between day NPAD scores and the regression slope was compared to the line of identity (slope m ¼ 1). Typical error values were determined by their 95% confidence limits. Item-factor score correlations and factor-total score correlations were analysed with the Pearson product moment correlation test. Validity. Face validity compared NPAD scores of the patient group with the asymptomatic group using an independent samples t-test. Construct validity was

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assessed with the Pearson product moment correlation between NPAD scores and external measures. Probability was considered significant at less than 5%. SPSS for Windows (11.5) was used for statistical analyses. Results

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The duration of clinical symptoms present at the time of examination was mean 25 + 7.4 days. The time taken to complete the NPAD was a maximum of 8 min. The patient group had a NPAD score of 52.6 (+12.5) implying pain of moderate intensity [1]. The difference in VAS scores between repeat measurements was not significant, implying no change in clinical status of the patient group between the two measurements. For test-retest total NPAD scores, the mean change did not exceed 70.37 (95% confidence interval 70.81 – 0.86) (Table I). The ICC values for between day measures were 40.92 and the linear regression (R2) values for total and factor scores 40.912 (Table II). In the linear regression analysis the slope calculated for between day total and factor scores was not significantly different from the line of identity (Table II). The typical error for between day total scores did not exceed 1.16 which implies that the actual test-retest error for the same clinical condition was low (Table II).

Item-factor correlation values were good (r 4 0.50) with a few exceptions (Table III). High correlation values (r 4 0.72) for each of the four factors with the total scores were analysed. Factor 4 score had the highest correlation (r ¼ 0.91) with the total NPAD score (Table III). Face validity of the NPAD was established when out of 63 patients questioned about the relevance of the scale to their condition, all answered ‘yes’. Face validity also compared the NPAD total scores of the patient group (n ¼ 57) (mean score 52.6 + 10.1 with the asymptomatic group (mean score 0.72 + 1.5). As expected there was a significant difference between the scores of the two groups (t ¼ 30.90, p 5 0.05). Convergent validity between Factor 2 scores and the NPRS neck was (r ¼ 0.30), and arm (r ¼ 0.33). The value improved when Factor 2 was assessed with NPRS maximum scores (r ¼ 0.48) (maximum of neck and arm scores). When factor 2 scores were calculated without including item 20 scores a further improvement to r ¼ 0.67 was seen (Table IV). Table III. Measure of correlation between each item and the respective factor score, and between each factor with the total NPAD score in a cervical radiculopathy patient group (n ¼ 57). Factor 1

Item 7 16 17 18

Table I. Mean of NPAD total and factor scores recorded over two consecutive days in a cervical radiculopathy group (n ¼ 57). Day 1 Mean (SD)

NPAD Total Factor Factor Factor Factor

1 2 3 4

52.65 11.40 16.47 7.38 17.39

(12.47) (2.48) (2.96) (2.35) (4.67)

Day 2 Mean (SD) 52.28 11.33 16.26 7.40 17.28

(9.78) (2.45) (2.88) (2.30) (4.52)

2

Change in mean (95% CI) 70.37 70.7 70.21 0.02 70.11

(70.81 – 0.86) (70.24 – 0.10) (70.44 – 0.02) (70.10 – 0.14) (70.31 – 0.10)

CI, Confidence Interval.

3

4

TE

ICC (95% CI)

R2

m

t

1 2 3 4

1.16 0.46 0.62 0.31 0.55

0.98 0.96 0.95 0.98 0.98

(0.97 – 0.99) (0.94 – 0.98) (0.92 – 0.97) (0.96 – 0.98) (0.97 – 0.99)

0.974 0.932 0.912 0.964 0.972

0.953 0.955 0.930 0.963 0.955

0.028 0.068 0.078 0.082 0.057

TE, Typical Error; ICC, Intra-class Correlation Coefficient; m, slope; The t values for the slope (difference calculated from 1) were not significant at p 5 0.05.

Pain interfering with driving/riding Neck stiffness Difficulty in turning neck Difficulty in looking up or down

0.68 0.57 0.81

0.58 0.52 0.59 0.75 0.70 0.17

13 14 15

Pain causing depression Pain affecting emotion Pain affecting ability to think

0.91 0.93 0.75

4

Pain interfering with sleep Pain interfering with social activities Pain interfering with recreational activities Pain interfering with work activities Pain interfering with personal care Pain interfering with personal relationships Trouble with overhead activities

0.59

9 10

12 19

FTC

0.72

0.81

Pain intensity Average pain intensity Worst pain intensity Pain in standing Pain in walking Relief with pain pills

11 Total Factor Factor Factor Factor

IFC

1 2 3 5 6 20

8 Table II. Regression analysis of NPAD total and factor scores measured on two consecutive days.

Item description

0.74

0.78

0.71 0.69

0.91

0.69 0.39 0.77 0.39

IFC, Item Factor Correlation; FTC, Factor Total Correlation; Correlation values derived by the Pearson product moment correlation.

Reliability of the Hindi version of the NPAD Table IV. Validity testing. Convergent validity tested between the NPRS scores measuring neck and arm pain intensity with factor 2. Divergent validity tested between VAS scores and NPAD factor scores for activity and emotional disturbances. R2

F

0.30 0.33 0.48 0.67

0.093 0.109 0.230 0.449

5.7 6.8 16.77 45.65

0.15 70.80

0.025 0.652

1.43* 104.69

R

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NPRS (neck) with factor 2 NPRS (arm) with factor 2 NPRS Max with factor 2 NPRS Max with factor 2 (minus item 20) VAS Activity with factor 4 VAS Depression with factor 3

All F values from the regression analysis suggested significant correlation at p 5 0.05 except VAS activity scores with factor 4 scores (*p ¼ 0.23); Max, Maximum; Minus item 20, Item 20 scores not included in the factor 2 scores.

Divergent validity scores between factor 4 and VAS Activity were low (r ¼ 0.15), and negative with VAS Depression (r ¼ 70.80) (Table IV). For all correlations tested for convergent and divergent validity, except VAS Activity and factor 4, the F value was significant. Discussion Based on a review of literature, this study acknowledged the NPAD as a valid and reliable measuring scale for cervical spine pain and adapted it for usage and acceptability in the Hindi language, translated it and tested its reliability and validity in a cervical radiculopathy patient group. Disability scales developed in a country reflect the expressions specific to the language and its sociocultural way of life [8]. Adaptation to local expressions and prevalent social/cultural lifestyle is often required. A few minor adaptations are acceptable if the original concept of the scale is kept intact [7]. The English language, and, to some extent the culture, has pervaded sections of the Indian society which prompted us to attempt a translation rather than develop a new instrument. The pilot study proved useful in evaluating patient comprehension and to check acceptability of the NPAD scale. This study adapted terminology and added explanations to the original English version of the NPAD and then translated these into Hindi, in order that future studies in India may use the NPAD in either language. Care was taken to maintain the original concept of the scale. In a previous study [7], the pilot study was conducted after translation to check the acceptability and feasibility of the translated version. Terminology that appears to be contentious in NPAD translation studies [7,8] are ‘recreational’ and ‘social activities’. In both French and Turkish languages these terms have a somewhat different meaning. The French [7] illustrated these activities

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with examples, as in the current study, whereas the Turkish investigators [8] provided examples to patients verbally. The Turkish [8] translation had a problem with item 7 (driving) and item 10 (working activities) because they were the least responded items (19.6% and 27.8% respectively). Although these items had a low response, the items were not excluded or modified. In the current study other modes of transport were included in item 7 because the percentage of Indians who own a motor vehicle is few compared to the entire population. A whole or a half score entails marking on the vertical line or grid, whereas a quarter score requires marking in the space between the vertical line and the grid. This physical design of the NPAD scale was confusing patients and therefore raised doubts about reliability of the marking. Consequently only whole scores were employed in the current study (0 – 5). A similar observation in the Turkish [8] study prompted these investigators to provide verbal explanations for marking whole, halves and quarters. The French [7] contacted the developers and replaced the subdivided VAS to a classical undivided VAS, their scoring changing to 0 – 2000 instead of 0 – 100. In the present study, the time taken to complete the NPAD was a maximum of 8 min. Completion time reported in other studies varies ranging from 15 – 20 min [8] and 1.3 – 20 min [7]. The developers of the scale [6] have proposed the NPAD would take less than 5 min. The test-retest reliability results in this study were excellent (r ¼ 0.91, p 5 0.05) and similar to previous reports (r ¼ 0.97, p 5 0.05) [7]. The difference in mean of the total scores was very small (70.37). The maximum typical error did not exceed 1.16, which is of consequence in longitudinal studies using the NPAD. Factor scores and total scores demonstrated excellent linear associations with coefficient of determination (R2) greater than 0.912. This explains most of the variation between the second day measurement compared to the first. Similar regression values (R2 ¼ 0.93) for repeat measurements have been observed earlier [6]. The high testretest scores were unlikely because of memory because the order of the questions was changed for repeat measures and five different delusive items were added to each day measure. The items in the NPAD can be represented by four factors [1] which represent four different domains and therefore, in this study, the results were calculated as item-factor correlations instead of item-total correlation (ITC). Each of the four factors was then correlated to the total score. Analysis revealed item 20 had a negligible correlation (r ¼ 0.17) with respective factor score 2. In an ITC analysis, item 20 correlation value was the lowest

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(r ¼ 0.44) among all items [1] although in the Turkish translation study [8] the value was much higher (r 5 0.58, p 5 0.001). Wheeler et al. [1] analysed data from the neck pain group using principal component analysis and five factors were identified which explained 76% of the variance. The authors chose to reduce the factors to 4 because only item 20 was loaded to factor 5. Item 20 was then added to factor 2. The four factors then explained 66.6% of the total variance. The low correlation values achieved in this study between item 20 and factor 2, probably underscores that it is an individual item. Additionally, in cervical radiculopathy, pain is associated with sensory and motor disturbances, and it is possible that the effect of pain medication on pain alone is not well appreciated. In this study another item which had low correlations was item 11 (personal care) (r ¼ 0.39) with factor 4. Similar results have not been reported earlier. Item 19 (overhead activities) was one of the items which the patients in the pilot group questioned. Although explanations were provided in the translated version, patients’ scores did not correlate highly (r ¼ 0.39) with factor 4 scores. A plausible reason may be that in Indian society, the presence of attendants and extended family members does not make it imperative for an individual to reach overhead and the actual impairment may not be experienced to its fullest. Face validity is a subjective judgement of whether a measurement makes sense. In order to have a valid measure of a social construct, merely achieving face validity is not sufficient. However, establishing face validity is of value, because without this aspect of validity one cannot achieve the other components of validity [11]. In this study, expected significant differences in scores were assessed between a radiculopathy patient cohort and an asymptomatic group for evaluating face validity. Convergent validity is supported when different methods of measuring the same construct provide similar results. Divergent validity examines whether a measure of one underlying construct can be differentiated from another construct. Observed and expected convergent and divergent validity suggest a good construct validity [7]. To test convergent and divergent validity, scales which would involve familiarity with the English language were not used as this would entail inclusion of subjects with bilingual skills or the scales would have to be translated. Instead 10 cm VAS and the 101 NPRS were employed to test construct validity. Convergent validity was assessed between factor 2 and the NPRS arm scores and neck scores. Moderate, although statistically significant, correlation values ¼ 0.33 were attributed to the fact that cervical radiculopathy patients, who may have high levels of neck pain, may not

necessarily have high levels of arm pain. Maximum scores of neck and arm pain were computed as ‘NPRS maximum’ which improved the correlation with factor 2 (r ¼ 0.48). Because previous analysis showed a poor item 20-factor 2 correlation, further analysis was conducted with NPRS maximum scores with factor 2 (without item 20 scores). The Pearson product moment correlation value improved further (r ¼ 0.67). Previous studies have achieved similar correlations between NPAD total scores and VAS pain scores for convergent validity (r ¼ 0.51)7 and (r ¼ 0.45)8, respectively. Divergent validity scores were as expected. No correlations (r ¼ 0.15, F ¼ 1.43, p ¼ 0.23) were achieved between the VAS Activity and the NPAD factor 4 scores. Negative significant correlations were achieved with the VAS Depression and factor 3 scores, which was due to the phrasing pattern of the VAS Depression question. Based on our experience with pain scores in this study, it is recommended that in future studies with cervical radiculopathy patients ‘neck pain’ be replaced by ‘neck/arm pain’, similar to the first two questions in the Northwick Park Questionnaire [3]. The NPAD has been tested to be efficacious and sensitive to change in clinical status [6,12]. A longitudinal study is being undertaken to assess the treatment efficacy and outcomes in cervical radiculopathy, treated conservatively and surgically using the NPAD. Conclusion Based on the results of this study, the Hindi version of the NPAD is a reliable and valid instrument for the assessment of pain and disability in cervical radiculopathy patients in an Indian clinical setting. (Annexure 1 for online version only).

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