Reliability and validity study of Sino-nasal outcome test 22 (Thai version) in chronic rhinosinusitis

Background Chronic rhinosinusitis (CRS) is one of common health conditions that affects patients' health-related quality of life. Our purpose is to assess the reliability and validity of Thai-version of Sino-Nasal Outcome Test 22 in chronic rhinosinusitis. Methods Permission for translation of SNOT-22 from English language to Thai language was obtained from the developer. The translation process was done based on the international standard of translation method. A total of 80 subjects were recruited into the study and divided into two groups comprising of 50 patients with chronic rhinosinusitis and 30 healthy volunteers. Cronbach's α and Intraclass correlation coefficient were evaluated for its reliability. Validity test was evaluated against VAS score, SF-36 (Thai version) questionnaire and CT scan (based on Lund-Mackay score). Responsiveness was assessed between pre-operative and post-operative scores in 34 patients. Results The Thai version of SNOT-22 showed good reliability according to high value of Cronbach's α coefficient (r = 0.929) and intraclass correlation coefficient (r = 0.935). It also showed good validity by its ability to differential the patients with chronic rhinosinusitis from normal (p < 0.001), and different severity of symptoms (p < 0.05). In addition, the SNOT-22 Thai version also showed good responsiveness when compared between pre-operative and post-operative scores (p < 0.001) and also well-performed in effect size calculation (1.37). Conclusion We demonstrated that Thai -version of SNOT-22 has good reliability and validity, suitable for evaluation of chronic rhinosinusitis symptoms together with severity of the disease and response to treatment. Trial registration Thai clinical trials registry TCTR20170320003. Date of registration 20/03/2017 (retrospectively registered).