Proportion of Patients in the United States Who Fill Their Nirmatrelvir/Ritonavir Prescriptions.

Introduction: Although real-world studies demonstrate that those prescribed nirmatrelvir/ritonavir (and particularly within 5 days of symptom onset) are less likely to experience severe COVID-19 outcomes, prior studies show that only a small fraction of patients with COVID-19 who are eligible for nirmatrelvir/ritonavir receive a prescription. Studies calculating the proportion of nirmatrelvir/ritonavir prescriptions filled and identifying individual- and pharmacy-level correlates of filling nirmatrelvir/ritonavir are lacking.

Methods: This retrospective cohort study included individuals aged ≥ 12 years with a nirmatrelvir/ritonavir prescription ordered at a large national retail pharmacy (December 22, 2021-August 12, 2023). Those taking contraindicated medications were excluded. For those with only one nirmatrelvir/ritonavir prescription ordered, the outcome was whether the prescription was filled (yes/no). In a subanalysis of these individuals, the outcome was whether the prescription was filled within 5 days of symptom onset (yes/no). For those with multiple prescriptions ordered, the outcome was whether > 1 (vs. 0 or 1) prescriptions were filled. A log-binomial regression with generalized estimating equations was used to identify individual (clinical and demographic) and pharmacy-level (percentage of trade area that is non-Hispanic white, urbanicity, US Census region, and tract-level area deprivation index) correlates.

Results: A total of 2,103,570 unique nirmatrelvir/ritonavir prescriptions were ordered for 1,985,990 individuals. Among the 95% of individuals prescribed only one nirmatrelvir/ritonavir course, 88% filled their prescription. Among those with > 1 prescription ordered, 77% (82,993/108,411) filled one and 13% (13,662/108,411) filled > 1. Patients ≥ 50 years of age and those with documented high-risk conditions were slightly more likely to fill prescriptions, regardless of whether one or multiple courses were ordered. Individuals with cancer, asthma, or taking corticosteroids or immunosuppressive medications were more likely to fill multiple prescriptions.

Conclusions: Most patients filled their nirmatrelvir/ritonavir prescriptions. Interventions to improve uptake should focus on increasing patient and provider awareness, reducing nirmatrelvir/ritonavir prescribing disparities, and ensuring treatment initiation within 5 days.