To evaluate the sensitivity of W.H.O presumptive diagnostic criteria in diagnosis of HIV infection in children <18 months admitted to UTH.

Background: Making a diagnosis of HIV infection in children aged less than 18 months remains a challenge in low resource set ups like Zambia due to scarcity of DNA PCR testing equipment which is the gold standard. Clinicians in rural areas have to depend on HIV ELISA tests and clinical diagnosis to start HAART as they wait for the DBS for DNA PCR 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. Information was gathered from caregivers by means of an interviewer administered questionnaire and the attending paediatrician’s case notes. Two milliliters of blood was then drawn for CD4% and HIV-DNA PCR assessment. Data was analyzed using SAS, version 9.1.3.
Results: Of the 299 exposed patients analyzed 111(37%) were HIV infected by DNA PCR. The median CD4% in the infected children was 18%. WHO presumptive diagnostic criteria (PDC) used on its own proved unreliable especially in infants younger than 6 months (46% with a specificity of 84%, 62% PPV and 72% NPV). Multivariate analysis was used to identify the most sensitive predictors when combined with the WHO PDC. WHO PDC with CD4% improved the sensitivity to 81% (95% CI 0.74 to 0.88) and specificity to 77% (95% CI 0.71 to 0.83), PPV of 67% and NPV of 87%. Assessed but did not improve the sensitivity were weight < 3rd percentile (56%), lymphadenopathy (50%), hepatomegaly (47%), Splenomegaly (47%) and nappy rash (47%). When the WHO-PDC, weight<3rd percentile, hepatomegaly, Splenomegaly, lymphadenopathy and CD4% were combined, the sensitivity improved to 86%, specificity 63% , PPV 58% and NPV of 88%.
Conclusion: The WHO-PDC clinical algorithm which has a sensitivity of 46% can be improved to 81% when combined with a CD4% <25% in children less than 12 months and CD4 %< 20% in those >12 months and <18 months also with increase in age above 6 months. However, DNA PCR still remains the most reliable in detecting HIV infection especially in the 0-6months age group.