Performance of modified WHO presumptive criteria for diagnosis of HIV infection in children <18 months admitted to University Teaching Hospital in Lusaka

Abstract

Background: Making a diagnosis of HIV infection in children aged less than 18 months remains a challenge in low resource settings like Zambia due to the limited availability of gold standard testing with HIV DNA PCR. Clinicians in rural areas have to depend on clinical diagnosis to start HAART asthey wait for the dry blood spot (DBS) for DNAPCR results sent from the urban centers.
Methods: This descriptive cross-sectional study was performed at the University Teaching Hospital, Lusaka, Zambia. 299 HIV-exposed children aged less than 18 months were enrolled following a consent procedure. Patients were evaluated for HIV infection based on the World Health Organization's presumptive diagnostic criteria (WHO-PDC), integrated management of childhood illnesses (IMCI) criteria, select physical exam abnormalities, and CD4% and findings were compared with HIVDNAPCR results.
Results: Of the 299 exposed patients analyzed, 111(37%) were found to be HIV-positive by DNA PCR. The median CD4% in the infected children was 18%. WHO-PDC used on its own had 23% sensitivity (95% CI 17-32%) and 93% specificity (88-96%), respectively, whereas IMCI criterion had 10% sensitivity (6-17%) and 97% specificity (94-99%), respectively.  Multivariate analysis was used to identify the most sensitive predictors when combined with the WHO-PDC and IMCI criterion. WHO-PDC with CD4% improved the sensitivity to 77% (68-83%) with a specificity of 83% (77-88%), positive predictive value (PPV) of 73% (64-80%) and negative predictive value (NPV) of 86% (80-90%). IMCI with CD4% improved sensitivity to 80% (71-87%) with a specificity of 88% (82-92%), PPV 78% (69-85%) and NPV 89% (84-93%). The addition of individual physical exam findings without CD4% improved the sensitivity of WHOPDC only modestly. When the WHO-PDC, weight<3rd percentile, hepatomegaly, splenomegaly, lymphadenopathy and CD4% were combined, the sensitivity improved to 85% (77-90%), specificity 63% (56-70%), PPV 58% (50-65%) and NPV of 88% (81-92%).
Conclusion: The WHO-PDC clinical algorithm can be improved when combined with a CD4% <25% in children less than 12 months of age and CD4% <20% in those between 12 and 18 months.

Keywords: HIV, early infant diagnosis, diagnosis, Zambia