Responsiveness and Interpretability of the Portuguese Version of the Neck Disability Index in Patients With Chronic Neck Pain Undergoing Physiotherapy

Study Design. A prospective cohort study with a 7-week follow-up of 113 patients with chronic neck pain undergoing physiotherapy. Objective. To examine the responsiveness of the Portuguese Version of the Neck Disability Index (NDI-PT), and to determine the minimal clinically important difference (MCID), minimal detectable change (MDC), and floor/ceiling effects. Summary of Background Data. Studies that determine MDC and MCID are needed to provide more accurate outcome evaluation and critically assess potential relevant sources for differences in the minimal important change values for the NDI. Methods. The NDI-PT was administered twice: at the baseline and after 7 weeks of physiotherapy treatment. A Global Transition Scale was used as an external criterion measure to distinguish between improved and nonimproved patients’ scores between baseline and follow-up. The responsiveness of the NDI-PT was assessed through anchor-based methods (correlation coefficient and receiver operating characteristics curves—ROC curves). The MCID was estimated by the ROC curve method, and the MDC through the standard Error of Measurement (SEM). Results. The NDI-PT revealed moderate responsiveness when applied to patients with chronic neck pain undergoing physiotherapy (ρ = 0.328 and area under the curve of 0.595, 95% confidence interval: 0.484–0.706). The MDC achieved 12 points, whereas the MCID was found to be 5.5 points. A complementary ROC analysis based on percentage differences in NDI-PT scores from baseline revealed an optimal cutoff point of 27%. The optimal cutoff point was found to be dependent of disability baseline scores. Conclusion. The NDI-PT demonstrated moderate levels of responsiveness. The amount of change in questionnaire scores perceived by the patient to be meaningful is smaller than the amount of change required to be statistically 95% confident that score change is not just measurement error. Level of Evidence: N/A

from Spine - Featured Articles - Featured Articles http://ift.tt/1H0yMlS
via IFTTT