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

Abstract

Malawi experienced its deadliest cholera outbreak in 2022, reporting over 50,000 cases and more than 1,700 deaths. This situation was further exacerbated by the Tropical Cyclone Freddy, which caused widespread damage to health infrastructure and strained Malawi's limited healthcare resources. Despite the scale of the outbreak, no evaluations were conducted to identify risk factors associated with cholera-related mortality among hospitalized individuals. This study filled that gap by characterizing the clinical and treatment-related factors contributing to cholera mortality in Malawi. A retrospective matched case-control study was conducted in August 2023 across four high-burden cholera districts: Blantyre, Mangochi, Lilongwe, and Nkhatabay. Medical records of 174 laboratory-confirmed cholera patients admitted between March 2022 and September 2023 were reviewed, including 87 matched pairs of deceased (cases) and surviving (controls) patients by age group and district. Data were extracted using a standardized mortality audit tool capturing socio-demographic characteristics, care-seeking behaviour, clinical status, and treatment received. Conditional logistic regression was used to identify factors associated with cholera mortality. Inadequate intravenous fluid management within the first 6 hours of admission was the strongest predictor of mortality (adjusted OR = 45.26, 95% CI: 9.09-225.30, p < 0.001). Other factors such as clinical status on admission showed a trend toward association but did not reach statistical significance. Timely and appropriate intravenous fluid administration within the first 6 hours of care is critical to reducing cholera mortality. We highlight an urgent need to strengthen the early response capacity in cholera treatment units, particularly during climate-related public health emergencies.