Objectives To determine whether blood lactate measured at the time of presentation to hospital predicted outcome in children with pneumonia in Malawi, and to understand the factors associated with high blood lactate concentrations in pneumonia.

Design Analysis of data from a prospective study of children presenting to Queen Elizabeth Central Hospital, Blantyre, with WHO-defined severe or very severe pneumonia.

Results Among 233 children with pneumonia, the median serum lactate concentration was 2.7 mmol/l (IQR 1.8–4.4 mmol/l). 77 children (33%) had a lactate concentration of 2.1–4.0 mmol/l, and 72 children (31%) had a lactate concentration >4.0 mmol/l. 92% of children who died (23/25) had lactate >2.0 mmol/l at the time of admission to hospital. There were 10 deaths (13%) among 77 children who had a serum lactate concentration of 2.1–4.0 mmol/l; and 13 deaths (18%) in the 72 children who had lactate >4.0 mmol/l. The relative risk of death if the lactate level was above 2 mmol/l was 7.48 (1.72–32.6); sensitivity 0.92, specificity 0.39, positive predictive value 0.15, negative predictive value 0.98. Multivariable analysis showed that hypoxaemia, hyperlactataemia and age ≤12 months were independent risk factors for death from pneumonia.

Conclusions Used in conjunction with clinical risk factors and pulse oximetry for measuring oxygen saturation, lactate could play an important role in identifying the sickest patients with pneumonia in developing countries.