Use of SOFA score in cardiac arrest research: A scoping review

Background: The Sequential Organ Failure Assessment (SOFA) score is a commonly used severity-of-illness score in cardiac arrest research. Due to its nature, the SOFA score often has missing data. How much data is missing and how that missing data is handled is unknown. Objectives: We conducted a scoping review on cardiac arrest studies using SOFA, focusing on missing data. Data sources: PubMed, Embase, and Web of Science. Study selection: All English-language peer-reviewed studies of cardiac arrest with SOFA as an outcome or exposure were included. Data extraction: For each study, quantity of missing SOFA data, analytic strategy to handle missing SOFA variables, whether/to what degree mortality influenced the amount of missing SOFA scores), SOFA score modifications, and number of SOFA measurements was extracted. Data synthesis: We included 66 studies published between 2006–2019. Five studies were randomized controlled trials, 26 were prospective cohort studies, and 25 were retrospective cohort studies. SOFA was used as an outcome in 36 (55%) and a primary outcome in 10 (15%). Nine studies (14%) mentioned the quantity of missing SOFA data, which ranged from 0 to 76% (median: 10% [IQR: 6%, 42%]). Twenty-seven (41%) studies reported a method to handle missing SOFA. The most common method used excluded subjects with missing data (81%). In the 50 studies using serial SOFA scores, 11 (22%) documented mortality prior to SOFA measurement; which ranged from 3% to 76% (median: 12% [IQR: 6%–35%]). Conclusions: Missing data is common in cardiac arrest research using SOFA scores. Variability exists in reporting and handling missing SOFA variables.