Responder Definition of a Patient-Reported Outcome Instrument for Laryngopharyngeal Reflux Based on the US FDA Guidance

Background: Different end-point measures may contribute to inconsistent therapeutic responses in relief of laryngopharyngeal reflux (LPR) symptoms. Objectives: We aimed to determine an a priori responder definition for a patient reported outcome instrument, the Reflux Symptom Index (RSI), using an anchor-based method, to interpret individual treatment benefit in patients with LPR, on the basis of the US food and Drug Administration guidance. Methods: Patients with chronic laryngeal symptoms suggestive of LPR underwent twice-daily 40 mg esomeprazole treatment for 12 weeks. We used a 50% or more reduction in the primary laryngeal symptom at week 12, an empirical criterion, as an anchor to dichotomize the participants into two groups, and to establish a responder definition of the RSI score change. The optimal cutoff point of the RSI score change was determined on the basis of the maximal Youden index of the receiver operating characteristic analysis. Results: The mean reduction in the RSI score was significantly greater in subjects with a 50%. or more reduction in the primary laryngeal symptom than in those without (-11.0 +/- 7.8 vs. -3.1 +/- 8.3, P < 0.0001). A reduction of six points or more in the RSI score at week 12 was considered to be the responder definition with a sensitivity of 0.79 and a specificity of 0.70. Conclusions: We propose an a priori responder definition derived from an empirical criterion according to the Food and Drug Administration guidance: a reduction of six points or more in the RSI score at week 12. This preliminary estimate provides a clinically meaningful change at an individual level, although additional studies and validations across various languages are required.