Determinants of cholera fatalities in Malawi: A case-control study of patient-level and clinical management factors in the 2022-23 outbreak

Malawi experienced its deadliest cholera outbreak in 2022, reporting over 50,000 cases and more than 1,700 deaths, resulting in a case fatality rate of 3.1%. The outbreak was exacerbated by the devastation caused by Tropical Cyclones Freddy, Ana, and Gombe, which strained healthcare resources. Despite the severity of the outbreak, no real-time evaluations of patient-level risk factors influencing cholera mortality among hospitalized patients were conducted. This study characterizes patient-level factors and treatment practices associated with cholera mortality in Malawi. A multisite case-control study was conducted in August 2023 across four cholera treatment units. A retrospective review of 174 medical records (confirmed by rapid antigen test or stool culture) was performed by a team led by trained medical officers. Cases (deceased) and controls (survivors) were matched based on age and district of diagnosis. Conditional logistic regression was used to assess associations between patient characteristics and mortality. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated for all predictors, with statistical significance set at p < 0.05. The strongest predictor of mortality was inadequate intravenous (IV) fluid management, with 95% of deceased patients classified as inadequately managed. Inadequate fluid management was associated with significantly higher odds of mortality (OR = 117, 95% CI: 14.3–959, p < 0.001). This study highlights critical gaps in adherence to cholera treatment protocols in Malawi’s treatment units, emphasizing the need for timely and adequate IV fluid management to reduce cholera-related deaths.