Symptomatic Illness and Low CD4 Cell Count at HIV Seroconversion as Markers of Severe Primary HIV Infection

Background: The risk/benefit of initiating ART in primary HIV infection (PHI) is unclear. The benefits are more likely to outweigh the risks in patients with severe PHI. An accepted definition of severe PHI is, however, lacking. Methods: CASCADE patients with HIV test interval <6 months were classified as severe and non-severe PHI based on whether the following traits were recorded in the first 6 months following seroconversion: severe specific pre-defined symptoms, central nervous system-implicated illness, and >= 1, >= 2 CD4<350 (and <500) cells/mm(3). For each definition, we used Kaplan-Meier curves and Cox survival models to compare time to AIDS/death, censoring at the earlier of last clinic visit or 1/1/1997, when combination antiretroviral therapy (cART) became available. Results: Among 1108 included patients mostly males (85%) infected through sex between men (71%), 366 were diagnosed with AIDS/died. The risk of AIDS/death was significantly higher for individuals with severe symptoms, those with >= 1 CD4<350 cells/mm(3) or >= 2 CD4 <500 cells/mm(3) in the first 6 months [aHR (95% confidence interval) 2.1 (1.4,3.2), 2.0 (1.5,2.7), and 2.3, (1.5-3.5) respectively]. Median [interquantile range] survival for patients with >= 2, >= 1 and no CD4<350 cells/mm(3) within 6 months of seroconversion was 3.9 [2.7,6.5], 5.4 [4.5,8.4] and 8.1 [4.3,10.3] years, respectively. The diagnosis of CNS-implicated symptoms was rare and did not appear to be prognostic. Conclusion: One CD4 count <350 or two <500 cells/mm(3) within 6 months of seroconversion and/or severe illness in PHI may be useful early indicators of individuals at high risk of disease progression.