Evaluating HIV testing algorithms for research, diagnosis and surveillance

The objective of the study was to evaluate the validity of the HIV testing algorithms used at St. Mary's Hospital Lacor (Gulu district, North Uganda) for research, diagnosis and surveillance. The validity of a new testing algorithm based on rapid tests for research and diagnosis was determined by testing 560 samples from the antenatal clinic at Lacor Hospital and using the old ELISA algorithm as a gold standard. The validity of a new testing algorithm for HIV surveillance, assuming the previously used Wellcozyme as a gold standard, was determined using 360 samples from the same antenatal clinic. Using the old ELISA algorithm as a gold standard, the new rapid test algorithm for diagnosis and research has a sensitivity of 90.6% and a specificity of 98.8%, yielding an accuracy rate in correctly classifying the results of 96.6%. In comparison to the Wellcozyme kit, the new testing algorithm for HIV surveillance has a sensitivity of 77.3% and a specificity of 96.8%, with no difference in the prevalence of HIV infection between the two testing schemes.The two testing algorithms evaluated in this study show good performances according to the purposes of their use. It is important that before full introduction of new HIV testing kits and algorithms into a setting, field evaluation studies are carried out to determine their validity.