Reflux Symptom Index: Translation to the Kazakh Language and Validation

BACKGROUND:This research focuses on the translation and validation of the Reflux Symptom Index (RSI) in Kazakh language and the comparison of its results among patients with symptoms of Laryngopharyngeal reflux (LPR) and without LPR symptoms. OBJECTIVE:This study aims to translate and validate the RSI in Kazakh language (Kz-RSI). METHODS:The RSI from the original American English version has been translated according to standard procedures into Kazakh language. The study included 248 patients, 124 LPR patients, and 124 asymptomatic controls. A final version of the Kz-RSI was tested twice: on Day 0 and Day 14 for participants without LPR symptoms and on Day 0 and posttreatment for those with LPR symptoms. Reliability, validity, and internal consistency of test-retest were calculated. RESULTS:The Cronbach's alpha value for Kz-RSI was 0.94, indicating excellent internal consistency. The single measurement absolute agreement of the interclass correlation coefficient was 0.90 (95% confidence interval [0.86; 0.93]), which indicates good retest reliability. The total Kz-RSI scores and each item were significantly higher in the LPR group than in the control group (P < 0.001). In the posttreatment LPR patient group, the Kz-RSI scores for each item and overall were significantly lower than the pretreatment scores (P < 0.001). CONCLUSIONS:Kz-RSI has been successfully translated and validated to identify LPR among the Kazakh-speaking population. Moreover, it is an inexpensive method with strong internal consistency, high retesting rates, reliability, and optimal clinical validity.