Uniform Research Case Definition Criteria Differentiate Tuberculous and Bacterial Meningitis in Children

Abstract

Tuberculous meningitis (TBM) research is hampered by low numbers of microbiologically confirmed TBM cases and the fact that they may represent a select part of the disease spectrum. A uniform TBM research case definition was developed to address these limitations, but its ability to differentiate TBM from bacterial meningitis has not been evaluated. We assessed all children treated for TBM from 1985 to 2005 at Tygerberg Children's Hospital, Cape Town, South Africa. For comparative purposes, a group of children with culture-confirmed bacterial meningitis, diagnosed between 2003 and 2009, was identified from the National Health Laboratory Service database. The performance of the proposed case definition was evaluated in culture-confirmed TBM and bacterial meningitis cases. Of 554 children treated for TBM, 66 (11.9%) were classified as "definite TBM," 408 (73.6%) as "probable TBM," and 72 (13.0%) as "possible TBM." "Probable TBM" criteria identified culture-confirmed TBM with a sensitivity of 86% and specificity of 100%; sensitivity was increased but specificity reduced when using "possible TBM" criteria (sensitivity 100%, specificity 56%). "Probable TBM" criteria accurately differentiated TBM from bacterial meningitis and could be considered for use in clinical trials; reduced sensitivity in children with early TBM (stage 1 disease) remains a concern.