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0 0.5 1 1.5 2+ Mortality 23% Improvement Relative Risk Ventilation -3% ICU admission -8% Paxlovid for COVID-19  Wan et al.  LATE TREATMENT Is late treatment with paxlovid beneficial for COVID-19? Retrospective 7,119 patients in China (February - July 2022) Lower mortality with paxlovid (p=0.001) Wan et al., Annals of Internal Medicine, Apr 2023 Favors paxlovid Favors control

Effectiveness of Molnupiravir and Nirmatrelvir–Ritonavir in Hospitalized Patients With COVID-19

Wan et al., Annals of Internal Medicine, doi:10.7326/M22-3057
Apr 2023  
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Target trial emulation retrospective with 7,119 patients in Hong Kong, showing lower mortality with paxlovid, but no significant difference for ventilation and ICU admission.
Confounding by treatment propensity. This study analyzes a population where only a fraction of eligible patients received the treatment. Patients receiving treatment may be more likely to follow other recommendations, more likely to receive additional care, and more likely to use additional treatments that are not tracked in the data (e.g., nasal/oral hygiene, (B), vitamin D (C), etc.) — either because the physician recommending paxlovid also recommended them, or because the patient seeking out paxlovid is more likely to be familiar with the efficacy of additional treatments and more likely to take the time to use them. Therefore, these kind of studies may overestimate the efficacy of treatments.
See also, (B).
Confounding by contraindication. Hoertel et al. find that over 50% of patients that died had a contraindication for the use of Paxlovid Hoertel. Retrospective studies that do not exclude contraindicated patients may significantly overestimate efficacy.
Black box warning. The FDA notes that "severe, life-threatening, and/or fatal adverse reactions due to drug interactions have been reported in patients treated with paxlovid" FDA.
Study covers paxlovid and molnupiravir.
risk of death, 23.0% lower, HR 0.77, p < 0.001, treatment 1,813, control 5,306.
risk of mechanical ventilation, 3.0% higher, HR 1.03, p = 0.89, treatment 1,813, control 5,306.
risk of ICU admission, 8.0% higher, HR 1.08, p = 0.82, treatment 1,813, control 5,306.
Effect extraction follows pre-specified rules prioritizing more serious outcomes. Submit updates
Wan et al., 30 Apr 2023, retrospective, China, peer-reviewed, 16 authors, study period 26 February, 2022 - 18 July, 2022.
This PaperPaxlovidAll
Effectiveness of Molnupiravir and Nirmatrelvir–Ritonavir in Hospitalized Patients With COVID-19
Eric Yuk Fai Wan, Vincent Ka Chun Yan, Anna Hoi Ying Mok, MPH Boyuan Wang, MPhil Wanchun Xu, Franco Wing Tak Cheng, Francisco Tsz Tsun Lai, Celine Sze Ling Chui, PhD Xue Li, Carlos King Ho Wong, Philip Hei Li, Benjamin John Cowling, Ivan Fan Ngai Hung, Chak Sing Lau, Ian Chi Kei Wong, Esther Wai Yin Chan
Annals of Internal Medicine, doi:10.7326/m22-3057
Background: Whether hospitalized patients benefit from COVID-19 oral antivirals is uncertain. Objective: To examine the real-world effectiveness of molnupiravir and nirmatrelvir-ritonavir in hospitalized patients with COVID-19 during the Omicron outbreak. Design: Target trial emulation study. Setting: Electronic health databases in Hong Kong. Participants: The molnupiravir emulated trial included hospitalized patients with COVID-19 aged 18 years or older between 26 February and 18 July 2022 (n = 16 495). The nirmatrelvirritonavir emulated trial included hospitalized patients with COVID-19 aged 18 years or older between 16 March and 18 July 2022 (n = 7119). Intervention: Initiation of molnupiravir or nirmatrelvir-ritonavir within 5 days of hospitalization with COVID-19 versus no initiation of molnupiravir or nirmatrelvir-ritonavir. Measurements: Effectiveness against all-cause mortality, intensive care unit (ICU) admission, or use of ventilatory support within 28 days. Results: The use of oral antivirals in hospitalized patients with COVID-19 was associated with a lower risk for all-cause mortality (molnupiravir: hazard ratio [HR], 0.87 [95% CI, 0.81 to 0.93]; nirmatrelvir-ritonavir: HR, 0.77 [CI, 0.66 to 0.90]) but no significant risk reduction in terms of ICU admission (molnupiravir: HR, 1.02 [CI, 0.76 to 1.36]; nirmatrelvir-ritonavir: HR, 1.08 [CI, 0.58 to 2.02]) or the need for ventilatory support (molnupiravir: HR, 1.07 [CI, 0.89 to 1.30]; nirmatrelvir-ritonavir: HR, 1.03 [CI, 0.70 to 1.52]). There was no significant interaction between drug treatment and the number of COVID-19 vaccine doses received, thereby supporting the effectiveness of oral antivirals regardless of vaccination status. No significant interaction between nirmatrelvir-ritonavir treatment and age, sex, or Charlson Comorbidity Index was observed, whereas molnupiravir tended to be more effective in older people. Limitation: The outcome of ICU admission or need for ventilatory support may not capture all severe COVID-19 cases; unmeasured confounders, such as obesity and health behaviors, may exist. Conclusion: Molnupiravir and nirmatrelvir-ritonavir reduced all-cause mortality in both vaccinated and unvaccinated hospitalized patients. No significant reduction in ICU admission or the need for ventilatory support was observed.
Disclaimer: The corresponding authors had full access to all of the data in the study and take final responsibility for the decision to submit it for publication.
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Late treatment
is less effective
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