The prognostic value of measures of acid/base balance in pediatric falciparum malaria, compared with other clinical and laboratory parameters

Newton CR, Valim C, Krishna S, Wypij D, Olola C, Agbenyega T, Taylor TE
Clin Infect Dis. 2005;41

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BACKGROUND: Identifying severe, life-threatening falciparum malaria in African children allows for the prompt institution of appropriate management. In the past 2 decades, hyperlactatemia and acidosis have been identified as being associated with mortality in patients with severe malaria, but measurement of blood lactate concentration and base excess is expensive and technically demanding. In this large, prospective study, we examined the prognostic value of acidosis and hyperlactatemia and compared these markers to clinically assessed variables. METHODS: We examined several clinical and laboratory measurements as prognostic markers of mortality in 14,605 parasitemic children admitted to 3 hospitals in Africa. Whole-blood lactate concentration and acid/base status were used to identify subjects who had hyperlactatemia and acidosis. RESULTS: Using cut-points established by sensitivity and specificity curves, the sensitivities and positive predictive values for both lactate concentration and base excess were low, the specificities were moderate, and the negative predictive values were high (>97%). No reliable clinical surrogates for hyperlactatemia or acidosis were identified. Addition of lactate concentration and base excess to predictive models with previously identified clinical features (Blantyre Coma Score, deep breathing, prostration, and weight-for-age Z score) and 1 laboratory measure (blood glucose level) did not appreciably improve models to predict mortality. CONCLUSIONS: Measurements of lactate concentration and acid/base balance are expensive to perform, and performance of the latter can be problematic. Severe falciparum malaria may be readily recognized in children at admission to hospitals in sub-Saharan Africa with use of simple, inexpensive means and does not require knowledge of lactate concentration and base excess.