Original Research
Validation of the Neck Disability Index in Serbian Patients With Cervical Radiculopathy

https://doi.org/10.1016/j.jmpt.2017.10.018Get rights and content

Abstract

Objective

The purpose of this study was to translate the Neck Disability Index into the Serbian language (NDI-S) and to investigate the validity of this version for use in Serbian population.

Methods

Fifty patients with cervical radiculopathy were enrolled in the study and completed a multidimensional questionnaire, including NDI-S. Inclusion criteria were ages between 18 and 65 years, Serbian speaking, no cognitive or hearing impairment, sharp and radiating neck and upper extremity pain that has lasted less than 12 months, radiculopathy signs evaluated by electromyoneurography and disc herniation, or spondylotic changes of cervical spine visualized on magnetic resonance imaging. Exclusion criteria were malignancy, previous cervical spine discectomy, trauma of the cervical spine and myelopathy, polyneuropathy, fibromyalgia, and psychiatric disorders. Validity was determined by the correlation of the Neck Disability Index, with pain measured by visual analogue scale, characteristics related to pain, and mental status. Also, factor structure of NDI-S was explored through factor analysis. Reliability was assessed through internal consistency (Cronbach’s α and item-total correlations).

Results

Correlation analysis between pain and NDI-S showed significant values (P < .01). The NDI-S correlated well with patients mental status (r = 0.421, P < .01). Cronbach’s α of NDI-S was 0.85, denoting excellent internal consistency of the questionnaire. Item-total correlations were significant and ranged from 0.328 to 0.789. Factor analysis demonstrated a 2-factor structure with an explained variance of 55%.

Conclusion

The NDI-S is a valid questionnaire to measure neck and arm pain related to disability in Serbian patients with cervical radiculopathy.

Introduction

Cervical radiculopathy (CR) typically presents as neck pain radiating to the upper extremity and is most commonly due to the compression of a cervical nerve root that causes pain and disability.1 Cervical radiculopathy affects approximately 1 person per 1000 of a population per year and is most often caused by degenerative spondylosis or a disk herniation.1 One study reports that patients with upper arm pain are more disabled and have less improved quality of life compared with patients who have neck pain only.2 Quantification of neck and upper extremity pain-related disability is crucial for the evaluation of the treatment and also for assessing clinical outcomes of disability.3

The Neck Disability Index (NDI) is a questionnaire developed by Vernon and Mior4 that measures problems with neck movements, neck pain intensity, effect of neck pain on concentration, and the level of interference in daily life activities. It has been translated and validated in many study populations and has shown stable psychometric properties.4, 5, 6 To our knowledge, no specific disease questionnaire that assesses disability in patients with neck pain and CR has ever been validated in Serbia. Therefore, the purpose of this study was to translate and validate the NDI in Serbian patients with CR.

Section snippets

Translation and Adaptation

The translation process was in accordance with standard methods that have been adopted internationally.7 The NDI was first translated into Serbian by 2 research study doctors who were fluent in English and blinded to each other. The translation was examined by the study team that included research study doctors and 1 doctor from an English-speaking area (a Serbian doctor living and working in London). The Serbian version of the NDI (NDI-S) was then translated into English again by a

Descriptive Data

Fifty patients with CR who fulfilled inclusion criteria were included in the study: 35 females and 15 males; mean age was 44.5 ± 10 (Table 1). Basic demographic data and lifestyle habits are outlined in the Table 1.

The mean value of NDI-S was 18.9 ± 7.42, denoting moderate disability. Of the 50 participants involved in the study, 17 participants (34%) had 1, the same missing item (“driving”). No missing data occurred across all other items of the NDI-S. No floor or ceiling effects were

Discussion

This study was conducted with the purpose of validating the NDI in Serbian patients with CR. The NDI-S showed acceptable psychometric properties that corresponded to those of translations in other languages. To our knowledge, this study is the first validity study of NDI in Serbian patients. No specific-disease questionnaire that assesses disability in patients with neck pain and CR has ever been validated in Serbia. The sample size in this study was adequate,8, 17 with clear inclusion criteria

Conclusions

The results of this study suggest that NDI-S is a valid questionnaire to measure neck and arm pain-related disability in Serbian patients with CR.

Funding Sources and Conflicts of Interest

No funding sources or conflicts of interest were reported for this study.

Contributorship Information

  • Concept development (provided idea for the research): M.D.J., L.M.K.

  • Design (planned the methods to generate the results): M.D.J., L.M.K., A.D.G.

  • Supervision (provided oversight, responsible for organization and implementation, writing of the manuscript): L.M.K., A.D.G., N.D.M., S.M.D.

  • Data collection/processing (responsible for experiments, patient management, organization, or reporting data): M.D.J., N.D.M., V.Z.J., S.I.K.D., M.K.H., S.M.D.

  • Analysis/interpretation (responsible for statistical

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