Statistical analysis was performed from August 24, 2019, through May 23, 2020. We calculated the overall rate of all-cause mortality per 1000 person-years, stratified by follow-up time (<50th percentile vs ≥50th percentile of follow-up time) and age (20-65 vs ≥65 years). We used the Cox proportional hazards regression model to estimate crude mortality hazards in comparing the active comparator group with exposure groups 1 and 2. Adjusted mortality hazards were then obtained after applying propensity score weighting, with SE estimates calculated via bootstrapping with 1000 replications (with a single imputation used within each sampling) to adjust for additional sources of variability introduced by the propensity score weighting process as well as multiple imputation. As previously described,8 NHANES reporting guidelines consider estimates to be statistically reliable with a sample size of more than 420.
