Inpatient Mortality and Risk Factors Among Hospitalized Medicare Beneficiaries Ages 65 and Older with COVID-19 Treated with COVID-19 Convalescent Plasma (CCP), During 2020-2021

Background: COVID-19 has had a substantial burden on older adults aged 65+. The study objective was to evaluate inpatient mortality among hospitalized Fee-for-Service (FFS) Medicare beneficiaries ages 65+ with COVID-19 treated with COVID-19 convalescent plasma (CCP) during August 2020-December 2021: overall, monthly, and by patient and hospital characteristics. Study Design and Methods: Our retrospective claims-based study utilized large Centers for Medicare & Medicaid Services administrative databases to assess inpatient COVID-19 stays with recorded CCP transfusions among FFS Medicare beneficiaries ages 65+. CCP transfusions were identified by recorded procedure codes, and inpatient mortality via the patient status discharge code. Crude inpatient mortality rates (per 100 CCP transfusion stays with COVID-19) and corresponding 95% confidence intervals were evaluated across a range of patient and hospital characteristics. Multivariate logistic regression analyses were used to assess potential risk factors. Results: The overall crude inpatient mortality was 25.5% (95%CI:25.2%-25.8%), declining from 30.7% (95%CI:29.1%-32.3%) in August 2020 to 7.4% (95%CI:3.8%-15.0%) in December 2021, p<0.001. The study identified significantly higher adjusted odds of inpatient mortality for each year of advancing age (1.06; 95%CI:1.06-1.07), immunocompromised (IC) vs. non-IC (1.14; 95%CI:1.05-1.24), males vs. females (1.20; 95%CI:1.15-1.25), Medicaid-eligible vs. not (1.13; 95%CI:1.07-1.20), medium (1.14; 95%CI:1.06-1.22) and large (1.09; 95%CI:1.01-1.19) compared to small hospitals, with ICU/CCU admission vs. not (2.71; 95%CI:2.57-2.85), mechanical ventilation<96 hours (13.11; 95%CI:12.11-14.20) and ≥96 hours (11.59; 95%CI:10.89-12.34) vs. not, among others. Discussion: The findings highlight importance of patient and hospital characteristics, including demographics, comorbidities, socioeconomic status, and COVID-19 severity, for inpatient mortality among Medicare beneficiaries receiving CCP.