Objective: To determine whether psychological status is an effect modifier of the previously observed low discriminatory capacity of Sinonasal Outcome Test-22 (SNOT-22) scores for Lund-Mackay computed tomography (CT) results.
Study design: Observational outcomes study.
Setting: Tertiary care center.
Subjects and methods: We assessed patients presenting with chronic sinonasal complaints who underwent CT of the sinuses within 1 month of completing the SNOT-22 instrument. SNOT-22 overall and domain scores were calculated, as were Lund-Mackay CT scores. The discriminatory capacity of SNOT-22 scores for CT results was determined using the receiver-operator characteristic area under the curve (ROC-AUC). Patient-Reported Outcome Measurement Information System (PROMIS) mental health T-scores were assessed, and stratified analyses were used to test for effect modification by psychological status.
Results: In stratified analyses, patients with better PROMIS mental health scores had SNOT-22 overall (ROC-AUC 0.96) and nasal domain scores (ROC-AUC 0.97-0.98) that were highly discriminatory for Lund-Mackay scores, while those with worse mental health scores did not (ROC-AUC 0.42-0.55, P < .007). Patients with better SNOT-22 psychological domain scores also had nasal scores that discriminated among CT results significantly better than those with worse psychological domain scores (ROC-AUC 0.65-0.69 and 0.34-0.35, respectively, P < .013).
Conclusions: Psychological status is an effect modifier of the relationship between SNOT-22 and Lund-Mackay scores. SNOT-22 scores were discriminatory for Lund-Mackay CT results in patients with better psychological status, while they were nondiscriminatory in those with worse psychological status. When assessing the relationship between subjective and objective measures of chronic rhinosinusitis, accounting for effect modification may have practical utility.
Keywords: computed tomography; diagnostic testing; effect measure modification; patient-reported outcome measure; predictive value; rhinosinusitis; validated instrument.