In this study we seek to evaluate current methodologies for observational comparative studies of inpatient COVID-19 treatments [Overall Study Objective]. To support this overall study objective, we have defined additional supporting objectives related to the research process [Process Objectives] as applied to an illustrative example of an observational study to evaluate the comparative effectiveness of inpatient COVID-19 treatments [Illustrative Example].~Process Objectives:~Characterize differences in study results when an intentional multiphase approach (IMA) to diagnostics and contingencies is applied to RWD analysis compared to an approach that pre-specifies all covariates and statistical approaches without consideration of whether key statistical assumptions hold (Single-phase Prespecification Approach, SPA).~Illustrative Example:~Our illustrative example will use a large population-based US claims data source to emulate a hypothetical target trial to assess the comparative effectiveness of IL6Ri (TCZ or SAR) versus JAKi (BAR or TOF) added to systemic corticosteroids of interest (CSI). The underlying hypothetical target trial of interest consists of patients hospitalized and requiring respiratory support for COVID-19 and receiving a CSI who are assigned to receive either an IL6Ri or JAKi in addition to CSI within 4 days after hospital/ICU admission. The patients are followed for up to 28 days for the outcomes of inpatient mortality and progression to IMV/ECMO. The Illustrative Example is separated into two sub-objectives based on the different COVID-19 severity populations of interest.~Illustrative Example - Objective I aims to characterize the risk of inpatient mortality [Primary Outcome] and progression to IMV or ECMO [Secondary Outcome] up to 28 days after IL6Ri or JAKi initiation among patients hospitalized with COVID-19 who initiate a CSI and require supplemental O2/NIV/HFO (but not IMV/ECMO).~Illustrative Example - Objective II aims to characterize the risk of inpatient mortality [Primary Outcome] up to 28 days after IL6Ri or JAKi initiation among patients admitted to the ICU at hospital admission with COVID-19 who initiate a CSI and require IMV/ECMO.~Hazard ratios (HR) and corresponding 95% confidence intervals (CI) will be estimated and reported for all outcome risks in Illustrative Example objectives.
To apply and compare two different methodological approaches (one applying diagnostics steps and contingencies and the other not) to the illustrative example described below:~Illustrative Example - Objective I aims to characterize the risk of inpatient mortality [Primary Outcome] and progression to invasive mechanical ventilation (IMV) or extracorporeal membrane oxygenation (ECMO) [Secondary Outcome] up to 28 days after interleukin-6 receptor inhibitors (IL6Ri) or janus kinase inhibitor (JAKi) initiation among patients hospitalized with COVID-19 who initiate a corticosteroid of interest and require supplemental oxygen / non-invasive ventilation / high flow oxygen (O2/NIV/HFO) (but not IMV/ECMO).~Illustrative Example - Objective II aims to characterize the risk of inpatient mortality [Primary Outcome] up to 28 days after IL6Ri or JAKi initiation among patients admitted to the ICU at hospital admission with COVID-19 who initiate a CSI and require IMV/ECMO.~Hazard ratios (HR) and corresponding 95% confidence intervals (CI) will be estimated and reported for all outcome risks in Illustrative Example objectives.