Minimal clinically important difference for the 22-item Sinonasal Outcome Test in medically managed patients with...

To determine the minimal clinically important difference (MCID) of the 22-item Sinonasal Outcome Test (SNOT-22) in individuals undergoing medical management for their chronic rhinosinusitis (CRS).

Prospective observational study.

Academic, tertiary care centre.

A total of 247 adults undergoing medical management for CRS.

At enrolment, participants completed a SNOT-22. At a subsequent follow-up visit, 2-12 months after enrolment, participants also completed a SNOT-22. At follow-up, participants also rated the change in their sinus symptoms and general health as "Much worse," "A little worse," "About the same," "A little better" or "Much better" compared with enrolment; these two questions were used as sinus symptom and general health anchor questions, respectively. The SNOT-22 MCID was calculated using distribution-based, anchor-based and receiver operating characteristic (ROC) curve-based methods.

Using the distribution-based method, the SNOT-22 MCID was 11.6. Using the sinus symptom anchor question, the SNOT-22 MCID was 10.5; applying the ROC method to the sinus symptom anchor yielded an MCID of 12.5. In comparison, using the general health anchor question, the SNOT-22 MCID was 8.3; applying the ROC method to the sinus symptom anchor yielded an MCID of 17.5. In all cases, the calculated MCID had a sensitivity of approximately 50-60% and specificity of approximately 80-90%.

Based on our results, we propose a SNOT-22 MCID of 12 in medically managed patients with CRS. The MCID, while specific, was not sensitive for identifying patients with CRS experiencing a noticeable improvement in sinus symptoms or general health.