Reliability and clinical validity of the Italian Reflux Symptom Index

Currently, there is no Italian version of the Reflux Symptom Index (RSI). The aim of this study was to develop an Italian RSI and to evaluate its internal consistency, reliability, and clinical validity. The study design used was a cross-sectional survey study. Eighty patients with a Reflux Finding Score (RFS) >7, and 193 asymptomatic subjects were included in the study. For the RSI reliability analysis, the appositely developed Italian RSI was filled twice, with a week interval, by the 80 patients and 80 control subjects. The test-retest reliability was assessed through the Pearson correlation test, whereas the Cronbach's alpha coefficient was used for internal consistency analysis. For the clinical validity assessment, the scores obtained in the pathological group were compared with the data from the asymptomatic individuals through the Student's t test. Finally, the correlation between RSI and RFS in the 80 patients was assessed. All of the patients filled in the entire questionnaire autonomously. The test-retest reliability in the patients, as well as in the control group, was very high (r>0.90); the internal consistency also showed very high values (alpha=0.99). The mean RSI score in the patients was 21.1+/-6.6, whereas in the control group it was 6.3+/-5.6; the difference was statistically significant (P=0.0001). The mean RFS score in the 80 patients was 9.2+/-2.7 and the correlation between RFS score and RSI score was rather high (r=0.89). The Italian RSI is easily administered, highly reproducible, and exhibits excellent clinical validity.