Nirmatrelvir-ritonavir addition to acute care formulary: a retrospective, multi-centre evaluation of quantitative economic and qualitative clinical outcomes

Objectives Evaluate the impact of acute care formulary addition of nirmatrelvir-ritonavir (NMV/r) on both economic and clinical outcomes among elderly hospitalized patients with mild-to-moderate COVID-19. Patients and methods This retrospective, multi-site cohort study included patients aged ≥70 years hospitalized with mild-to-moderate COVID-19 who received NMV/r or remdesivir (RDV) between March and December 2024. The primary outcome was drug-acquisition cost avoidance attributed to NMV/r formulary availability. Secondary outcomes included progression to severe disease, acute care treatment duration, hospital length of stay (LOS), ICU admission, 30-day readmission and 28-day mortality. Results Among 100 patients (50 per group) with mild-moderate COVID-19, NMV/r use produced an estimated US$66 197 in cost avoidance, corresponding to $1324 ± $678 per patient (95% CI $1136–$1512). The total hospitalization cost difference between the groups was $461 511 in favour of NMV/r. NMV/r prescribing was more common for mild COVID-19 (23 of 50 versus 12 of 50, P = 0.021) while RDV prescribing was more common for moderate COVID-19 (27 of 50 versus 38 of 50, P = 0.021). Patients in the NMV/r group had lower rates of disease progression (22% versus 46%, P = 0.02), shorter acute care treatment duration (2 versus 3 days, P < 0.01) and shorter hospital LOS (2 versus 4 days, P < 0.01). No adverse events leading to discontinuation were observed in either group. Conclusions Economic data from this study of elderly adults with mild-moderate COVID-19 suggest that addition of NMV/r to hospital formulary should be considered to support optimal resources consumption, while the clinical impact of NMV/r availability may be better studied through evaluating mild or moderate COVID-19 disease independently.