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New HIV Life Expectancy study: Women and Aboriginals in British Columbia Fall Far Short of Normal Life Expectancy
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7th IAS Conference on HIV Pathogenesis, Treatment and Prevention, June 30-July 3, 2013, Kuala Lumpur
Mark Mascolini
Among people starting combination antiretroviral therapy (ART) in Canada since 2000, life expectancy remains substantially lower than in the general population of Canada [1]. Shortfalls in life expectancy are particularly marked for women and Aboriginal people.
Research on populations across the world confirms that combination ART has prolonged life expectancy. But whether HIV-positive adults starting ART can now expect to live as long as HIV-negative people of the same age and gender remains controversial. Researchers at the British Columbia Centre for Excellence in HIV/AIDS observed that "as life expectancy has increased over time" in antiretroviral-treated people, "inequities have emerged" between HIV-positive subgroups. To characterize these inequities and to compare life expectancy with and without HIV, the British Columbia team conducted this study.
The analysis focused on data from people who started ART in British Columbia since 2000 and on Statistics Canada survival estimates between the 1991 and 2006 censuses. The investigators used abridged life tables to estimate life expectancy at age 25, defining life expectancy as the average number of additional years a 25-year-old will live if current age-specific mortality remains constant. For people who began ART, the researchers calculated mortality by person-time to death, loss to follow-up, or administrative censoring. They used multivariate survival analysis to identify survival predictors in people starting ART.
The study group included 3890 people who began ART in British Columbia since 2000, including 768 women (20%), 1477 people (38%) with a history of injection drug use, and 484 people (12%) with Aboriginal ancestry. Factors favoring longer survival were starting ART in a more recent year and starting with a CD4 count above 350. Factors linked to shorter survival were older age, an AIDS diagnosis or a higher viral load when starting ART, HCV positivity, and Aboriginal ancestry.
Factors associated with shorter survival (adjusted hazard ratios):
-- Each decade of age: aHR 1.38, 95% confidence interval (CI) 1.25 to 1.53, P < 0.001
-- Each 10-fold higher viral load: aHR 1.50, 95% CI 1.18 to 1.19, P = 0.001
-- AIDS before ART: aHR 2.17, 95% CI 1.72 to 2.75, P < 0.001
-- Aboriginal ancestry: aHR 3.52, 95% CI 2.51 to 4.94, P < 0.001
-- HCV positive: aHR 2.75, 95% CI 2.14 to 3.53, P < 0.001
Factors associated with longer survival (adjusted hazard ratios):
-- Starting ART in 2004-2007 vs 2000-2003: aHR 0.67, 95% CI 0.54 to 0.84, P < 0.001
-- Starting ART in 2008-2011 vs 2000-2003: aHR 0.38, 95% CI 0.29 to 0.52, P < 0.001
-- Starting ART at CD4 count above 350: aHR 0.45, 95% CI 0.28 to 0.71, P < 0.001
Class of antiretroviral (boosted or unboosted protease inhibitor or nonnucleoside) did not affect survival in this analysis.
Women, men, and Aboriginals with HIV all had substantially shorter life expectancies than their counterparts in the general population. The decrements were particularly large for women and Aboriginals:
Addition life years at age 25 with HIV versus the general population:
-- Men: 34.1 years with HIV versus 52.6 years in general population: difference 18.5
-- Women: 27.4 years with HIV versus 57.9 years in general population: difference 30.5
-- Aboriginals: 21.0 years with HIV versus 49.1 years in general population: difference 28.1
Limiting the analysis to non-Aboriginal people who started ART in 2008-2011 reduced these differences between men and women with HIV and their counterparts in the general population.
The researchers noted that their analysis is limited by the different periods covered in people with and without HIV and by inability to account for HIV deaths occurring outside British Columbia and general population deaths outside Canada. With those limitations in mind, they concluded that "considerable gaps in life expectancy still exist in Canada, especially among women and persons of Aboriginal ancestry."
The links between higher viral load and shorter survival, and between higher CD4 count and longer survival, lend weight to arguments favoring starting ART earlier in the course of HIV infection.
Reference
1. Hogg RS, Chan K, Cescon A, et al. Considerable gaps in life expectancy among HIV-positive individuals initiating HAART in British Columbia, Canada. 7th IAS Conference on HIV Pathogenesis, Treatment and Prevention, June 30-July 3, 2013, Kuala Lumpur. Abstract TUPE256.
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