Variables

We assessed patient demographics, socioeconomic status, medical history in the year prior, prior healthcare and medication exposures, overweight and obese status, immunocompromised status, frailty, and COVID-19 vaccination status as potential predictors. Socioeconomic status was assessed using the area deprivation index (ADI) grouped into quintiles from least to most deprived [14]. We assessed drugs with clinically significant potential for drug–drug interaction with nirmatrelvir/ritonavir (with recommendations to adjust concomitant medication and monitor, or to temporarily withhold concomitant medication, if clinically appropriate) [12, 13]. Overweight and obesity status were defined using CDC body mass index (BMI) categories for adults [15]. Immunocompromised status was based on a previously described algorithm [16]. Frailty was defined using the ICD-10 updated Veterans Affairs Frailty Index (VA-FI) [17]. COVID-19 vaccination status was based on recommendations for immunocompetent patients.