OBJECTIVES: To examine the association between mechanical ventilation (MV) status and hospital readmission (primary) and mortality (secondary) for COVID-19 patients following discharge from the hospital in the early vs later phases of the pandemic.

METHODS: Retrospective observational study using inpatient health records of patients hospitalized with COVID-19 in the Northwell Health system between 3/1/2020 and 1/31/2021; patients were followed through 6/30/2021 (or lost to follow-up). Rates, hazards, and odds of readmission and mortality between early (3/1/2020 through 6/30/2020) vs late (7/1/2020 through 1/31/2021) admissions were estimated using Cox proportional hazards regression and binary logistic regression models. Propensity score matching (PSM) was used to balance potential confounders between MV and non-MV patients. Potential confounders that were not balanced (absolute standardized difference ≥0.10) following PSM were included as covariates.

RESULTS: The full sample comprised 17,562 patients with 10,211 early and 7,351 late admissions. Characteristics of the full sample with early/late admissions were: median age 62/65, 46%/49% female, 37%/52% white, and 8%/4% of early/late admissions receiving MV. The odds (95% CI) of readmission for MV vs non-MV was 4.30 (3.30-5.63)/9.79 (6.71-14.27) for early/late admissions. In the PSM sample (n=1,660 early/602 late admissions), 50% of early/50% of late admissions received MV; of these, 33% early/30% late admissions were readmitted. Odds (95% CI) of readmission was 3.56 (2.75-4.60)/9.85 (5.53-17.57) for early/late admissions. Odds (95% CI) of mortality for MV vs non-MV was 3.88 (2.62-5.73)/11.86 (5.65-24.90) for early/late admissions.

CONCLUSIONS: Though rates of readmission and all-cause mortality were higher earlier in the pandemic, MV treatment for COVID-19 was more strongly associated with readmission and mortality later in the pandemic. This suggests that when alternative treatments became available later in the pandemic, patients receiving MV were sicker. Patients who receive MV treatment for COVID-19 may need additional follow-up to prevent adverse outcomes following discharge from inpatient treatment.