Nirmatrelvir-ritonavir significantly reduces severe COVID-19 outcomes in diverse Taiwanese populations: Comprehensive evidence from a large-scale longitudinal cohort study in Taiwan

Background: Nirmatrelvir-Ritonavir (NR) has proven effective for mild to moderate COVID-19 patients at risk of disease progression. Following its emergency use authorization in Taiwan in January 2022, this study aims to evaluate its impact on severe COVID-19 outcomes across different patient demographics in Taiwan. Methods: We performed a retrospective analysis of a database that includes data from three hospitals in Northern Taiwan. Patients with COVID-19 in 2022 were paired by propensity score matching based on NR prescription. Cox proportional hazard regression analysis calculated hazard ratios (HR), adjusting for confounding factors. Subgroup analysis determined HRs across patient characteristics. Results: Among 95,096 patients, 3329 were in the NR group, and 12,807 in the non-NR group. NR users demonstrated significantly better prevention of severe outcomes: intubation (HR=0.296 [95 % CI: 0.187–0.469], p = 0.0482); ICU admission (HR=0.327[0.108–0.991], p < 0.001); mortality (HR=0.195 [0.101–0.378], p < 0.001). Subgroup analysis revealed significantly lower intubation risks for NR users among both sexes, aged 18–65 or ≥ 65 years, BMI < 30, and patients with diabetes mellitus (DM), cardiovascular disease (CVD), or chronic obstructive pulmonary disease (COPD). ICU admission risk was lower for NR users among males, aged ≥ 65 years, and BMI < 30. Mortality risk was lower for NR users among both sexes, aged ≥ 65 years, BMI < 30, and patients with DM, CVD, or COPD. Conclusion: NR significantly reduces the risk of severe COVID-19, particularly among older adults and those with pre-existing conditions, supporting NR as an essential treatment for high-risk COVID-19 patients.