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MI Rates Converge in California Health System Groups With and Without HIV: trend down in HIV+
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16th Conference on Retroviruses and Opportunistic Infections,
February 8-11, 2009, Montreal
Mark Mascolini
Researchers from the Kaiser Permanente healthcare system in California were among the first to record a higher myocardial infarction (MI) rate in people with HIV than in uninfected people [1]. In an updated analysis at this meeting, the same investigators reported that MI rates in Kaiser clients with and without HIV have converged to the point of statistical nonsignificance [2].
The new study involved 20,305 people with HIV seen from 1996 through June 2008 and 203,050 people without HIV matched to the HIV group for age and gender. Patient age averaged 41 years, 90% were men, 56% of the HIV group were white, as were 47% of the non-HIV group.
Kaiser investigators counted 264 hospital admissions for MI and 160 for stroke in the HIV group and 1800 admissions for MI and 1136 for stroke in controls. In an analysis unadjusted for other risk factors, those numbers translate into an MI rate of 3.0 per 1000 person-years with HIV and 1.7 per 1000 person-years without HIV (P < 0.001). The yearly age- and gender-adjusted change in MI rates measured -5% in the HIV group (P = 0.004) and -1% in the non-HIV group (P = 0.296).
A graph plotting crude hospitalization rates for MI shows an up-and-down pattern in the HIV group: 2.5 per 1000 person-years in 1996-1997, 3.3 in 1998-1999, 2.8 in 2000-2001, 3.7 in 2002-2003, 3.1 in 2004-2005, and 2.5 in 2006-2008. Meanwhile, the crude rate inched up in the non-HIV group from 1.3 in 1996-1997, to 1.5 in 1998-1999, 1.4 in 2000-2001, 1.7 in 2002-2003, 1.9 in 2004-2004, and 2.0 in 2006-2008. The difference between the HIV group and the non-HIV group lost statistical significance only in 2006-2008 (P = 0.088).
Unadjusted stroke rates measured 1.8 per 1000 person-years with HIV and 1.1 per 1000 person-years without HIV (P < 0.001). Age- and gender-adjusted yearly change in stroke rates were 0% in the HIV group (P = 0.939) and +3% in the non-HIV group (P < 0.001). Hospital admissions for stroke stayed fairly constant in people with HIV from 1.7 per 1000 person-years in 1996-1997 to 2.0 in 2006-2008. The stroke admission rates rose steadily in the non-HIV group from 0.6 in 1996-1997 to 1.5 in 2006-2008. The difference between the HIV group and the non-HIV group remained statistically significant in 2006-2008 (P < 0.001).
The average Framingham heart disease risk score among all HIV-infected Kaiser clients fell from 7.2 in 2000-2001 to 6.4 in 2006-2008, even though the HIV population aged from an average 44.6 years in 2000-2001 to 47.2 years in 2006-2008.
A graph plotting use of stavudine and tenofovir in antiretroviral-treated people describes a neat X with the crossover coming around 2003. Around the same time, prescriptions of atazanavir among protease inhibitor-treated patients took off on a track paralleling tenofovir. Despite this jump in atazanavir use, lipid-lowering prescriptions rose steadily from 1996 through 2008 in people taking PIs--and also in people not taking PIs.
The Kaiser investigators noted that their study is limited by its failure to capture nonhospital MIs and strokes. The study's strengths include the large number of people treated over more than a decade, the comparison of people with and without HIV in the same healthcare system, and the comprehensive capture of hospital events.
The Kaiser team proposed that the declining MI hospitalization rate and the flat stroke rate may reflect (1) a shift to more lipid-friendly antiretroviral regimens, (2) heavier prescription of lipid-lowering agents, and (3) effective management of heart disease risk factors, which is reflected in the falling Framingham score in an aging population.
References
1. Klein D, Hurley LB, Quesenberry CP Jr, Sidney S. Do protease inhibitors increase the risk for coronary heart disease in patients with HIV-1 infection? J Acquir Immune Defic Syndr. 2002;30:471-477.
2..Hurley L, Leyden W, Xu L, et al. Updated surveillance of cardiovascular event rates among HIV-infected and HIV-uninfected Californians, 1996 to 2008. 16th Conference on Retroviruses and Opportunistic Infections, February 8-11, 2009, Montreal. Abstract 710.
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