November 6, 2008
A poster at the joint 2008 ICAAC/IDSA meeting in Washington, DC presented data from the US HOPS study (1994-2006) that showed HAART and preventive therapies have greatly reduced and stabilized the rates of AIDS-defining opportunistic conditions (ADOCs). What may be alarming about the results is that some of these ADOCs are being diagnosed at higher CD4 counts than what were seen earlier in the epidemic.
The study looked at 7,825 people over 3 periods: 1994-1997, 1998-2001, and 2002-2006. The average age at study start was 38 years and average CD4 counts were 295 cells. Four out of five were male, 57% were white and 58% were men who had sex with men.
The types of ADOCs included Kaposi's sarcoma (KS), cytomegalovirus (CMV), Mycobaterium avium complex (MAC), esophageal candidiasis and non-Hodgkin's lymphoma (NHL), among many others. Recurrent pneumonia and salmonella septicemia were not included.
In general, the rates of all ADOCs dropped dramatically in the first period, which makes sense given the introduction of protease inhibitors and multi-drug regimens during that time. Over the next period, the rates of MAC, NHL and esophageal candidiasis decreased further. Then, during the third period, MAC and AIDS-defining malignancies continued to decline while the rates of most other ADOCs had stabilized.
However, what stands out is that average CD4 counts at a KS diagnosis increased over the three periods at 38, 107 and 143 cells. The rates for NHL (73, 164 and 243 cells on average) and HIV encephalopathy (43, 210 and 233 cells on average) also increased across the periods. Additionally, CD4s increased slightly for other ADOCs, such as CMV and esophageal candidiasis, though these were not statistically significant. The study's presenter cautioned the low rates of these ADOCs may limit their observations, especially those in the third period.
Even so, the reasons why KS and a couple other OIs are now being diagnosed at higher CD4 counts are unclear. One reason could be that improved health care has screened and diagnosed these conditions more regularly, and therefore earlier in an individual's HIV disease and likely at higher CD4s. Another reason could be unknown, adverse shifts in the epidemiology of these OIs. For instance, over the past few years, a peculiar type of KS has emerged in generally healthy individuals.
The best news from this study is that the rate of ADOCs has dropped dramatically and has stabilized since 2002. However, along with data from other studies, this study may be signaling a nearly imperceptible shift in HIV disease. The virus may be becoming more stubborn and virulent, which may change how ADOCs appear and ultimately change the standards of care for screening and diagnosing them.