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).