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Fractures at Earlier Age in HIV+ Men Versus HIV-Negatives in MACS
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XIX International AIDS Conference, July 22-27, 2012, Washington, DC
Mark Mascolini
HIV-positive men in the US Multicenter AIDS Cohort Study (MACS) appeared to have a higher osteoporotic fracture risk at an earlier age than HIV-negative men in that cohort [1]. Among HIV-positive men, the fracture risk rose steadily with age and tripled among those 65 and older.
Previous studies document a higher fracture rate in HIV-positive people than in the general population [2-4]. But these studies did not compare fracture rates in the HIV group and a demographically similar group of HIV-negative people. That's what the MACS team set out to do by gauging osteoporotic fracture incidence--the new fracture rate--in HIV-positive gay men in the cohort and HIV-negative cohort members, who are considered at risk for HIV infection.
The investigators recorded osteoporotic fractures according to the FRAX definition--fractures of the hip, humerus (upper arm), forearm, or spine--that MACS members reported or recalled during twice-yearly visits between October 1996 and 2011.
All men were at least 30 years old. Age averaged 45.2 in HIV-positive men and 47.5 in HIV-negative men. Average body mass index was somewhat lower in the HIV group (25.0 kg/m2) than in the no-HIV group (26.5 kg/m2). (Lower body mass index raises the risk of fracture.) A higher proportion of HIV-positive men than negative men were current smokers (31% versus 24%). (Smoking is a recognized fracture risk factor.) A lower proportion of HIV-positive men than negative men were Caucasian (70% versus 82%). (Whites have a higher fracture risk than blacks.)
Among 5106 men tracked through 73,548 person-visits, there were 53 FRAX-defined fractures in HIV-positive men and 50 in HIV-negative men. The crude fracture incidence rate was 0.15 fractures per 100 person-years in the HIV group and 0.13 fractures per 100 person-years in the HIV-negative group.
After statistical adjustment for body mass index and race, the incidence of FRAX-defined fractures rose with age compared with the 30-to-49-year-old reference group:
For 50-64-year-olds: adjusted incidence rate ratio (aIRR) 1.19 (95% confidence interval [CI] 0.78 to 1.83, not significant)
For 65-years-old or older: aIRR 2.93 (95% CI 1.48 to 5.80)
In this same analysis, HIV infection raised the FRAX-fracture risk 38%, but that association fell short of statistical significance (aIRR 1.38, 95% CI 0.93 to 2.04).
The interaction of age and HIV status approached statistical significance (P = 0.14), a finding suggesting that older HIV-positive men run a higher osteoporotic fracture risk than older HIV-negative men. Among 50-to-64-year-old men, the incidence rate ratio was 1.78 in HIV-positive men compared with 30-to-49-year-olds. Among men 65 and older, the incidence rate ratio was 2.44 in HIV-negative men and 3.50 in HIV-positive men compared with 30-to-49-year olds.
The MACS investigators concluded that the increasing fracture rate as men age becomes apparent in HIV-positive men at younger ages than in HIV-negative men. They suggested their findings "provide support for recommendations for osteoporosis screening in HIV-infected men between ages 50-70 years."
The researchers called for further research to confirm the impact of lifestyle factors (such as smoking and alcohol) and comorbidities (such as hepatitis C virus infection) on fracture incidence differences between HIV-positive and negative men. They also believe future research should pursue potential HIV-specific fracture risk factors, such as CD4 count, viral load, antiretroviral exposure, lipodystrophy, and frailty.
References
1. Walker Harris V, Althoff K, Reynolds S, et al. Incident bone fracture in men with, or at risk for, HIV-infection in the Multicenter AIDS Cohort Study (MACS), 1996-2011. XIX International AIDS Conference. July 22-27, 2012. Abstract MOPE086.
2. Hansen AB, Gerstoft J, Kronborg G, et al. Incidence of low and high-energy fractures in persons with and without HIV infection: a Danish population-based cohort study. AIDS. 2012;26:285-293.
3. Young B, Dao CN, Buchacz K, Baker R, Brooks JT; HIV Outpatient Study (HOPS) Investigators. Increased rates of bone fracture among HIV-infected persons in the HIV Outpatient Study (HOPS) compared with the US general population, 2000-2006. Clin Infect Dis. 2011;52:1061-1068.
4. Triant VA, Brown TT, Lee H, Grinspoon SK. Fracture prevalence among human immunodeficiency virus (HIV)-infected versus non-HIV-infected patients in a large U.S. healthcare system. J Clin Endocrinol Metab. 2008;93:3499-3504.
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