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. 2010 Dec 16;5(12):e15569.
doi: 10.1371/journal.pone.0015569.

Defining clinical malaria: the specificity and incidence of endpoints from active and passive surveillance of children in rural Kenya

Ally Olotu  1 , Gregory Fegan, Thomas N Williams, Philip Sasi, Edna Ogada, Evasius Bauni, Juliana Wambua, Kevin Marsh, Steffen Borrmann, Philip Bejon
Affiliations

Defining clinical malaria: the specificity and incidence of endpoints from active and passive surveillance of children in rural Kenya

Ally Olotu et al. PLoS One. .

Erratum in

Abstract

Background: Febrile malaria is the most common clinical manifestation of P. falciparum infection, and is often the primary endpoint in clinical trials and epidemiological studies. Subjective and objective fevers are both used to define the endpoint, but have not been carefully compared, and the relative incidence of clinical malaria by active and passive case detection is unknown.

Methods: We analyzed data from cohorts under active and passive surveillance, including 19,462 presentations with fever and 5,551 blood tests for asymptomatic parasitaemia. A logistic regression model was used to calculate Malaria Attributable Fractions (MAFs) for various case definitions. Incidences of febrile malaria by active and passive surveillance were compared in a subset of children matched for age and location.

Results: Active surveillance identified three times the incidence of clinical malaria as passive surveillance in a subset of children matched for age and location. Objective fever (temperature≥37.5°C) gave consistently higher MAFs than case definitions based on subjective fever.

Conclusion: The endpoints from active and passive surveillance have high specificity, but the incidence of endpoints is lower on passive surveillance. Subjective fever had low specificity and should not be used in primary endpoint. Passive surveillance will reduce the power of clinical trials but may cost-effectively deliver acceptable sensitivity in studies of large populations.

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Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Figure 1
Figure 1. Location of the cohorts used in the study.
The map shows the location of the cohorts used in the analysis. Colored regions represent the locations where the cohorts were located. The sub-locations within each location are also shown, some of which have the same name as the cohort.
Figure 2
Figure 2. Variation of geometric parasite density mean with distance from Pingilikani dispensary.
Variation of geometric mean parasite densities with distance from Pingilikani dispensary. Parasite densities have been converted into log10 scale.
See this image and copyright information in PMC

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