The Revised Reflux Symptom Index (R-RSI): Development, Internal and External Validation Study

Abstract

Introduction: This study proposes a revised version of the Reflux Symptom Index (R-RSI), a seventeen-item questionnaire that was revised to increase the suspicion of laryngo-pharyngeal reflux disease (LPRD). Methods: Internal validation involved 213 participants, comprising160 subjects without a previous LPRD diagnosis and 53 subjects with a self-reported previous diagnosis of LPRD with or without gastro-esophageal reflux disease (GERD). Test-retest reliability and internal consistency were calculated. For the external validation, 56 patients (independent from the previous cohort) were enrolled to explore the R-RSI Screening Properties and determine a cut-off using 24-h MII-pH as the gold standard. Results: R-RSI test-retest reliability was high, both for the total score (ICC: 0.970) and for each item (ranging from 0.876 to 0.980). Cronbach’s alpha was 0.910, indicating excellent internal consistency of the questionnaire. Participants with a previous self-reported diagnosis scored significantly higher (mean 24.94 ± 7.4; median 26, IQR 20-29) than those without a previous diagnosis (mean 4.66 ± 5.3; median 4, IQR 1-6) (p-value < 0.0001). Participants with both previous LPRD and GERD diagnoses had higher scores (27.20 ± 7.8) compared to those with only LPRD (21.77 ± 5.5) (p-value=0.003). Using 24-h MII-pH diagnosis as a gold standard, the optimal R-RSI cut-off point was determined to be 18, with a sensitivity of 84.5% and a specificity of 81.8%, positive predictive value of 95% and negative predictive value of 60%. Conclusions: Our results suggest that the R-RSI may be useful to suspect LPRD, with or without GERD. The R-RSI is a self-administered patient-reported outcome questionnaire that demonstrates excellent reliability and high screening properties. Employing a cut-off of ≥18 the R-RSI can assist in diagnosing and monitoring LPRD.