Impact of HAART on Incidence of Primary HIV-Associated Thrombocytopenia
Thrombocytopenia induced by HIV infection typically improves with highly active antiretroviral therapy (HAART); however, cases of primary HIV-associated thrombocytopenia (PHAT) continue to be reported in the literature. We examined the incidence of PHAT over 28 years in the U.S. Military HIV Natural History Study (NHS).
Retrospective NHS data from 1986 to 2013 including 5,697 participants were analyzed. PHAT was defined as subjects diagnosed with idiopathic thrombocytopenic purpura with a nadir platelet count < 100,000 cells/mm3, and no other identifiable cause including known drugs and opportunistic infections. Subjects were excluded if coinfected with hepatitis B or C or diagnosed with cirrhosis, leukemia, and/or solid tumor malignancies. Variables included demographic data, platelet count, CD4 count, and HIV viral load (VL) at the time of PHAT diagnosis, and antiretroviral use. Time periods were categorized as pre-HAART (PH) 1986-1995, early-HAART (EH) 1996-2001, and later HAART (LH) 2002-2013. The relationship of CD4 count and VL with platelet count was studied. Descriptive statistics and mixed model linear regression with random intercept were used.
A total of 218 participants met the case definition of PHAT. 86% of cases occurred prior to 2002. The incidence of PHAT per 1,000 patient years was 15.4, 4.5, and 1.9 during PH, EH, and LH respectively (p <0.001). Median (IQR) CD4 count (cells/mm3) at PHAT diagnosis was 156 (30, 406), 262 (148, 378), and 380 (255, 517) over the same three time periods (p=0.016). Of the 67 patients with PHAT during the HAART eras, 33 (49%) were antiretroviral naïve. VL recorded within four months prior to nadir platelet count was available in 56 patients. Of these, viremia was detected in 54 (95%) participants, of which 29 (54%) were antiretroviral naive. Laboratory data collected during 1996-2013 in patients diagnosed with PHAT in the HAART eras showed strong correlation between log10 VL and platelet count (p <0.001).
The incidence of PHAT has markedly decreased in the HAART era, although viremic individuals, including those with healthy CD4 cell counts, may be at risk. Further decline in incidence may be another benefit to current recommendations to begin HAART as early as possible.
W. P. Bradley, None
A. Ganesan, None
B. Agan, None