Validity and Reliability of a German Version of Reflux Symptom Index.

Objective: The Reflux Symptom Index (RSI) is a widely used self-administered questionnaire for assessing laryngopharyngeal reflux (LPR). This study aimed to develop a German version of the RSI (G-RSI) and to evaluate its reliability, clinical validity, and responsiveness.

Study design: prospective, controlled, cross-sectional study.

Methods: This case-control study included 95 patients with LPR symptoms and 60 asymptomatic control subjects. The RSI was translated into German using a forward-backward methodology. Participants completed the G-RSI at baseline (G-RSI d0), and LPR patients completed it again after 14 days (G-RSI d14) and after a 12-week treatment period (G-RSI w12). Reliability was analyzed using Cronbach's alpha and intraclass correlation coefficients (ICC). Internal validity was evaluated by comparing the G-RSI scores of patients and controls. Responsiveness was assessed by comparing the pretreatment and post treatment scores. The G-RSI cutoff for determining the presence or absence of LPR was examined using receiver operating characteristic analysis.

Results: The Cronbach's α for the G-RSI was 0.924, indicating high internal consistency. Test-retest reliability was excellent (ICC = 0.92). The G-RSI demonstrated high internal validity, with significant differences between patient and control scores (P < 0.001). Responsiveness was also high, with significant improvements in G-RSI scores after treatment (P < 0.001). A G-RSI cut-off value of 13 was indicative of LPR, with high sensitivity (97.4%) and specificity (90.5%).

Conclusions: The German RSI demonstrated high reproducibility, excellent clinical validity, and responsiveness after transcultural adaptation. It is a valuable tool for the initial symptom assessment and evaluation of therapeutic interventions in individuals with suspected acid LPR in outpatient clinics and primary healthcare settings.