Observational Study of Convalescent Plasma for Treatment of Veterans With COVID-19

The convalescent plasma (CP) of individuals who have recovered from COVID-19 may help reduce symptoms and mortality when given to ill patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Clinical trials are needed to provide definitive evidence of the benefits and harms of CP in the treatment of COVID-19. While clinical trials are underway, observational research plays a critical role in providing preliminary scientific evidence to guide clinical practice. This observational study aims to estimate the association between CP therapy and mortality after 30 days in a sample of SARS-CoV-2-positive patients with non-severe illness. Patients include those hospitalized at a facility within the Veterans Health Administration (VHA) of the Department of Veterans Affairs (VA), the largest integrated healthcare system in the United States. Using VA electronic health record data, the study is designed to emulate a target trial of convalescent plasma transfusion and mortality. The primary exposure of interest is the use or non-use of COVID-19 convalescent plasma, and the primary outcome is 30-day all-cause mortality. A nested trial design will be used, in which patients will be followed from each day in which eligibility criteria are met (while hospitalized and after date of first positive SARS-CoV-2 test) for 30 days. The association between CP therapy and mortality will be assessed using pooled logistic models to estimate 30-day cumulative incidence curves, risk differences, and hazard ratios. Inverse probability weighting derived from propensity scores will be employed to minimize confounding by indication and other biases.