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KS, NHL, and Encephalopathy Getting Diagnosed at Higher CD4 Counts in US Cohort
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48th ICAAC, October 25-28, 2008, Washington, DC
Mark Mascolini
CD4 count at diagnosis of Kaposi sarcoma (KS), non-Hodgkin lymphoma (NHL), and HIV encephalopathy rose consistently from 1994 through 2006 in the US HIV Outpatient Study (HOPS) cohort [1]. But the rate of combined opportunistic malignancies dropped steeply through the most recent study period, 2002-2006, as did the rate of Mycobacterium avium complex (MAC). The study also disclosed trends toward higher CD4 counts at diagnosis of cytomegaloviral (CMV) disease and esophageal candidiasis, the most common opportunistic disease
HOPS investigators figured annual incidence (first diagnosis) of opportunistic diseases in 7825 cohort members grouped into three periods: 4228 people in 1994-1997, 4401 in 1998-2001, and 4476 in 2002-2006. Median age of the cohort stood at 38 years, 81% of cohort members were men, 57% were white, and 58% were gay.
Opportunistic diagnoses nose-dived in 1994-1997, and new diagnoses of NHL, MAC, and esophageal candidiasis continued to fall in 1998-2001. Diagnoses of combined opportunistic malignancies and MAC kept dropping in 2002-2006.
In 1994 the most frequent opportunistic diagnoses in HOPS were CMV disease (incidence 46.2 per 1000 person-years), Pneumocystis pneumonia (PCP) (36.4), MAC (33.9), KS (30.2), and esophageal candidiasis (18.7). Esophageal candidiasis rose to the top diagnosis spot in 2006 (5.6 per 1000 person-years), while PCP and CMV remained prominent in second (4.2) and third (2.9) place, while NHL (1.7) and HIV encephalopathy (1.7) tied for fourth. The new diagnosis rate of combined opportunistic malignancies plummeted from 40.6 per 1000 person-years in 1994 to 2.6 in 2006.
Median CD4 counts at diagnosis of the 2 AIDS cancers (KS and NHL) and HIV encephalopathy climbed steadily and significantly over the three treatment periods:
Median CD4 count at first diagnosis:
⋅ KS (n = 108): 38 in 1994-1997, 107 in 1998-2001, and 143 in 2002-2006, P < 0.001
⋅ NHL (n = 38): 73 in 1994-1997, 164 in 1998-2001, and 243 in 2002-2006, P = 0.0001
⋅ HIV encephalopathy (n = 37): 43 in 1994-1997, 210 in 1998-2001, and 233 in 2002-2006, P = 0.03
Median CD4 count at first diagnosis of esophageal candidiasis and CMV disease rose marginally across the three periods--from 43 in 1994-1997 to 89 in 2002-2006 in 145 people with candidiasis (P = 0.09) and from 20 to 41 in 219 people with CMV disease (P = 0.09).
The HOPS investigators speculated that "increases in median CD4 count at diagnosis of KS, NHL, and HIV encephalopathy may signal a shift in the epidemiology of these OIs in the HAART era." But they cautioned that their analysis is limited by the low incidence of new opportunistic diseases, especially in the most recent period. The HOPS team did not suggest why such an epidemiologic shift might occur. One can imagine that greater awareness of NHL and encephalopathy in more recent years contributed to earlier diagnosis of those conditions. But that logic seems unlikely to explain earlier diagnosis of dermatologic KS, which is so readily apparent to both patients and clinicians.
Reference
1. Buchacz K, Baker RK, Palella FJ, et al. Rates of AIDS-defining opportunistic conditions (ADOCs) and CD4 cell counts at ADOC diagnosis in the U.S. HIV Outpatient Study (HOPS), 1994-2006. 48th Annual International Conference on Antimicrobial Agents and Chemotherapy (ICAAC). October 25-28, 2008. Washington, DC. Abstract H-2330.
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