Cost-effectiveness of outpatient COVID-19 antiviral treatment with nirmatrelvir/ritonavir versus usual care in Swedish patients with various risk factors.

Aims: Nirmatrelvir/ritonavir (NMV/r) is an orally administered antiviral indicated for the outpatient treatment of adult patients with mild-to-moderate COVID-19 at high risk for disease progression to severe illness. We estimated the cost-effectiveness of NMV/r versus best supportive care for 54 patient cohorts, specified according to age, vaccination status and comorbidity burden.

Materials and methods: A previously published and validated cost-effectiveness model was utilized and adapted to the Swedish setting. The model used a short-term decision-tree (1 year) followed by a lifetime 2-state Markov model. The short-term decision-tree captured costs and outcomes associated with the primary infection. Post-acute COVID-19 syndrome was only considered in terms of quality-of-life decrements for one year. Baseline hospitalization and mortality risks were taken from a Swedish, nationwide, uniquely granular, Omicron-era, real-world study. NMV/r effectiveness were taken from an Omicron-era US real-world study. Remaining inputs were informed by previous COVID-19 studies and publicly available Swedish sources.

Results: The incremental cost-effectiveness ratios (ICERs) showed a large variation ranging from almost nine million SEK for some of the youngest cohorts to being dominant (i.e. cost-saving with higher gains in quality-of-life vs standard of care) for twelve elderly cohorts. In general, higher age in combination with non-recent (>180 days) or no vaccination led to lower ICERs. Specifically, NMV/r was cost-effective for all but one patient cohorts at least 70 years old, and for most patient cohorts 60-69 years old.

Limitations: As the COVID-19 landscape changes, symptom burden and baseline risks constantly change. Thus, the cost-effectiveness of NMV/r will change with time. However, the future risks could be related to the risks in the current study, and thus remain useful for decision makers.

Conclusions: This study shows that NMV/r is a cost-effective or even cost-saving treatment option for many patient cohorts, including most elderly and not-recently vaccinated patients with at least some comorbidity burden.