Investigating the responsiveness of the Persian version of functional rating index in patients with chronic non-specific neck pain: brief report

Background: It is important to use reliable, valid, and responsive instruments to assess the treatment outcomes. The functional rating index (FRI) is a patient reported outcome measure to assess the pain and function in patients with neck and low back pain. The FRI has been translated and culturally adapted into Persian language. The purpose of this study was to investigate the responsiveness of Persian functional rating index in patients with chronic non-specific neck pain (CNSNP). Methods: The adult patients with CNSNP recruited from Shariati Hospital in Tehran and filled the Persian functional rating index (PFRI), Persian neck disability index (PNDI), and pain numerical rating scale (NRS) before and after 10 physiotherapy sessions, from March to July 2017. The patients completed the global rating change scale after treatment. For statistical analyses, the effect size (ES), standardized response mean (SRM), Guyatt response index (GRI) were used. The Spearman or Pearson test was used for correlation analyses. The area under the receiver operating curve (ROC) and minimal clinically important difference (MCID) were calculated. Results: In this study, 30 patients (female 17) with a mean of age 45.6 years [standard deviation (SD) 13.8] participated. The mean duration of neck pain was 14.7 months (SD 12.8). Significant strong and moderate correlations were identified between PFRI with PNDI and GRC scores (r= 0.78 and r= 0.69). The respective ES and SRM values were 0.73 and 0.78 for PFRI. The GRI was 5.58. The AUC was 0.89 (P= 0.001). MCID was 11.7%. Conclusion: This study confirms that the Persian functional rating index is responsive for assessing disability in Persian speaking patients with chronic non-specific neck pain.