Validating a novel index (SWAT-Bp) to predict mortality risk of community-acquired pneumonia in Malawi

Community-acquired pneumonia is a major cause of mortality worldwide. Early assessment and initiation of management improves outcomes. In higher-income countries, scores assist in predicting mortality from pneumonia. These have not been validated for use in most lower-income countries.

To validate a new score, the SWAT-Bp score, in predicting mortality risk of clinical community-acquired pneumonia amongst hospital admissions at Queen Elizabeth Central Hospital, Blantyre, Malawi.

The five variables constituting the SWAT-Bp score (male [S]ex, muscle [W]asting, non-[A]mbulatory, [T]emperature (>38°C or <35°C) and [B]lood [p]ressure (systolic<100 and/or diastolic<60)) were recorded for all patients with clinical presentation of a lower respiratory tract infection, presumed to be pneumonia, over four months (N=216). The sensitivity and specificity of the score were calculated to determine accuracy of predicting mortality risk.

Median age was 35 years, HIV prevalence was 84.2% amongst known statuses, and mortality rate was 12.5%. Mortality for scores 0-5 was 0%, 8.5%, 12.7%, 19.0%, 28.6%, 100% respectively. Patients were stratified into three mortality risk groups dependent on their score. SWAT-Bp had moderate discriminatory power overall (AUROC 0.744). A SWAT-Bp score of ≥2 was 82% sensitive and 51% specific for predicting mortality, thereby assisting in identifying individuals with a lower mortality risk.

In this validation cohort, the SWAT-Bp score has not performed as well as in the derivation cohort. However, it could potentially assist clinicians identifying low-risk patients, enabling rapid prioritisation of treatment in a low-resource setting, as it helps contribute towards individual patient risk stratification.