Validity and Responsiveness of Chronic Rhinosinusitis Control Test Subdomains

OBJECTIVE: The chronic rhinosinusitis control test (CRCT) is a patient-reported outcome measure that measures, quantifies, and classifies CRS control. The CRCT has a sinonasal subdomain and an impairment subdomain. The objective of this study is to psychometrically validate the CRCT subdomains. METHODS: A cohort of 701 adult CRS patients was recruited and completed a CRCT, as well as overall symptom severity (OSS), SNOT-22, and EQ-5D quality of life (QOL) questionnaires. A subset of participants completed these questionnaires at a second time point to establish responsiveness to change (N = 283). Psychometric validation was performed by establishing criterion validity and responsiveness for the CRCT subdomain scores in these CRS patients. Minimal clinically important difference (MCID) values for improvement/worsening were determined for the CRCT subdomain scores using distribution-based and anchor-based methods. RESULTS: The CRCT sinonasal and impairment subdomain scores significantly correlate with and are responsive to measures of CRS symptom severity (OSS), CRS-specific QOL (SNOT-22), and general QOL (EQ-5D). The CRCT sinonasal subdomain is more reflective of sinonasal symptom burden and has an MCID for improvement/worsening of ≥ 3 points, while the impairment subdomain is more reflective of general QOL and has an MCID for improvement/worsening of ≥ 1 point. CONCLUSIONS: The CRCT sinonasal and impairment subdomain scores may serve as psychometrically validated outcome measures that provide additional insights into a patient's CRS disease state and overall CRS control in addition to the CRCT score. MCID values for the CRCT subdomain scores may serve as benchmarks for judging change in the subdomain scores. LEVEL OF EVIDENCE: N/A.