Neck disability index, Visual analog scale, and Likert scale in patients receiving pharmacotherapy for neck pain: How good do they correlate?

Abstract

Background: Neck disability index (NDI) is a patient self-assessed outcome measurement tool to assess disability due to neck pain. Improvement in pain severity score by a pain intensity numerical rating scale may not necessarily produce a significant change in NDI after treatment. Aims and Objectives: This study was undertaken to study the correlation between the pain status rated by the patient using qualitative scales with the NDI in patients with neck related problems. Materials and Methods: It was prospective observational study conducted in Physical Medicine and Rehabilitation Department of Tertiary care Teaching Hospital in Kerala for duration of 6 months. 170 patients, with M: F ratio-1:2.9, having neck pain were included and treated with centrally acting muscle relaxants and analgesics for 2 weeks. Patients were assessed on their initial visit and followed up after 2 weeks. Patient rating of pain status was measured using visual analog scale (VAS) and a 5-item Likert scale varying from excellent to bad. Disability level due to neck pain was determined using NDI. Analysis was done with correlation coefficient, paired t-test and Wilcoxon signed ranks test using SPSS 20. Results: VAS and Likert scale rating showed a positive correlation with NDI, both before (correlation coefficient = 0.663, 0.589) and after (correlation coefficient = 0.845, 0.776) pharmacotherapy. Significant changes in NDI (t = 28.199, P < 0.001), Likert scale (Z value = 11.03, P < 0.001), and VAS (t = 28, P < 0.001) were observed after pharmacotherapy. Conclusions: Study correlated patients rating of pain status themselves and NDI, and NDI can be used as an effective tool to evaluate pharmacotherapy.