Responsiveness and convergent validity of the chronic rhinosinusitis patient-reported outcome (CRS-PRO) measure in CRS patients undergoing endoscopic sinus surgery

Background: The chronic rhinosinusitis patient-reported outcome (CRS-PRO) measure is a 12-item measure with previously demonstrated validity in chronic rhinosinusitis (CRS) patients receiving medical therapy. This study establishes the factor structure, responsiveness, and convergent validity of the CRS-PRO following endoscopic sinus surgery (ESS). Methods: Northwestern CRS Subject Registry patients had pre-ESS, 3-month (n = 111; CRS without nasal polyps [CRSsNP] = 60, CRS with nasal polyps [CRSwNP] = 51), and 6-month (n = 86; CRSsNP = 47, CRSwNP = 39) post-ESS assessments where patients completed the CRS-PRO, 22-item Sino-Nasal Outcome Test (SNOT-22), and four Patient-Reported Outcomes Measurement (PROM) Information System (PROMIS) short forms (general health measures). Patients had pre-ESS objective testing (endoscopic and radiographic assessment). Factor analysis was conducted using principal axis factoring with varimax rotation on the baseline CRS-PRO. The clinically important difference (CID) was estimated using both distribution-based and anchor-based methods. Results: Factor analysis found the CRS-PRO comprised the “rhino-psychologic,” “facial discomfort,” and “cough” factors, which were responsive to ESS and correlated with the other PROMs. The changes observed in the CRS-PRO at 3 months had strong correlation with the corresponding changes in SNOT-22 (r = 0.792, p < 0.0001) and moderate correlations with changes in PROMIS fatigue and sleep domains. These changes had a very large effect size (Cohen's d 1.44) comparable to the longer SNOT-22 (Cohen's d 1.41) with slightly larger effect sizes observed in CRSwNP compared to CRSsNP patients. Similar convergent validity and responsiveness were observed in the 6-month data. The CRS-PRO CID was estimated to be between 5.0 and 7.5 (midpoint 6.0) using distribution-based and anchor-based methods. Conclusion: This study demonstrates the validity and responsiveness of the CRS-PRO in subjects receiving ESS.