PREDICTING CD4 COUNTS IN HIV-INFECTED BRAZILIAN INDIVIDUALS - A MODEL-BASED ON THE WORLD-HEALTH-ORGANIZATION STAGING SYSTEM

CD4 cell counts are one of the best available surrogate markers for di sease progression; they are widely used laboratory parameters in clini cal trials and commonly used indicators for the introduction of primar y prophylaxis and antiretroviral therapy. However, measurement is too expensive to be done in most developing countries. The objective of th is study was to derive a model for prediction of CD4 counts <200 cells /mm(3) based on the proposed World Health Organization (WHO) staging s ystem for HIV infection and widely available laboratory parameters. On e hundred and six consecutive patients enrolled in a prospective cohor t study who were not taking anti-HIV drugs or prophylaxis for opportun istic infections were included. Blood tests were performed within 72 h of the outpatient visit. Lymphocyte phenotyping was done by flow cyto metry. Two models based on the WHO staging system, hematocrit and tota l lymphocyte counts, were developed. The two models had sensitivity >9 0% and specificity >83%. These results indicate that the combined use of simple clinical and laboratory parameters can predict CD4 counts <2 00 cells/mm(3) with high sensitivity and specificity. Similar studies should be conducted in other countries. Should our findings be confirm ed, intervention strategies based on this model of potential universal applicability should be devised and validated.