Evaluation of latent class analysis and decision thresholds to guide the diagnosis of pediatric tuberculosis in a Rwandan reference hospital.

SETTING

A pediatric ward of a university hospital in Kigali, Rwanda, a region with a high HIV seroprevalence.

OBJECTIVE

To estimate the diagnostic accuracy of symptoms, signs, and paraclinical investigations for tuberculosis in children, and to propose a clinical rule based on the results.

DESIGN

During a 2-year period all children with cough for more than 2 weeks and/or fever for more than 2 weeks and/or reported weight loss were prospectively included. A set of clinical and paraclinical data were analyzed with latent class analysis. Comparison of post-test probability based on this analysis with a therapeutic threshold for TB was used to develop a guideline.

RESULTS

In the 309 children HIV prevalence was 56%, bacteriology was positive in 9%, and the tuberculin skin test (TST) was >10 mm in 20%. TB prevalence was 32%. Bacteriology and TST had a specificity of 97% and cough had a sensitivity of 91%. Decision analysis suggests treating children presenting one of the inclusion criteria, combined with positive bacteriology or TST >10 mm or contact with a TB patient.

CONCLUSIONS

Latent class analysis confirmed earlier identified predictors for TB and allowed development of an easy to use clinical rule, applicable in reference hospitals of countries with high HIV endemicity.