Reliability, Validity and Responsiveness of the Sino-Nasal Outcome Test (SNOT-22) in Japanese Patients

Abstract

　Objectives: In the diagnosis and treatment of rhinosinusitis, evaluation of the subjective symptoms is as crucial as that of the objective findings. The 22-item Sino-Nasal Outcome Test (SNOT-22) is used globally as a common measure of the symptoms of rhinosinusitis. Our goal was to translate and validate the SNOT-22 for a Japanese cohort.

　Design, setting, and participants: The Japanese version of SNOT-22 was developed using forward and backward translations by two interpreters. Three experienced Japanese otorhinolaryngologists confirmed the translations. To evaluate the validity of using this questionnaire, we conducted a prospective cohort study of 97 rhinosinusitis patients who had undergone endoscopic sinus surgery (ESS) at our institute; we also recruited twenty-two healthy volunteers.

　Main outcome measures: To evaluate the SNOT-22, the internal consistency, test-retest reliability, known-group differences, and responsiveness to treatment were analyzed. The clinical interpretability was assessed by calculating the minimum important difference (MID).

　Results: The internal consistency was high, with a Cronbach's α-value of 0.86. The test-retest reliability coefficient was 0.82, indicating good reliability for repeated measures. The total SNOT scores was 37.8±16.9 (average±SD) in the rhinosinusitis patients and 6.5±5.8 in the healthy volunteers, with a significant difference between the two groups (p<0.01). For the 85 patients who completed the SNOT-22 postoperatively, the average score improved significantly to 11.7±11.6, (p<0.01), indicating good responsiveness. The MID was 15.7 for the total score and the clinical efficacy rate in the patients who underwent ESS at our institute was 69.7%. These findings indicate the clinical interpretability of changes in the SNOT scores. Conclusion: The SNOT-22 is a reliable and valid tool to assess the quality of life in Japanese patients.