COVID-19 hospitalization risk after outpatient nirmatrelvir/ritonavir use, January to August 2022, North Carolina
EHR retrospective 44, 671 patients with 4,948 receiving paxlovid, showing lower hospitalization with treatment.
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
c19early.org, c19early.org (B), vitamin D
c19early.org (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.
Malden et al. confirm significant bias in the use of paxlovid, showing that
treated patients are more likely to be from affluent neighborhoods, be more
health-conscious, and have better access to care.
Therefore, these kind of studies may
overestimate the efficacy of treatments.
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.
This study is excluded in the after exclusion results of meta
analysis:
only a fraction of eligible patients received treatment and these patients may be more likely to follow other recommendations, receive additional care, and more more likely to use additional untracked treatments such as vitamin D and nasal/oral hygiene.
risk of hospitalization, 84.0% lower, HR 0.16, p = 0.002, treatment 4,948, control 39,723.
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Effect extraction follows pre-specified rules prioritizing more serious outcomes. Submit updates
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Henderson et al., 21 Feb 2024, retrospective, USA, peer-reviewed, 11 authors, study period January 2022 - August 2022.