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Bone density drop over time no greater with than without HIV in Dublin cohort
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UPBEAT Study EACS 2013: Lean mass has a greater effect on bone mineral density than fat mass; data from a cohort of HIV-positive and HIV-negative subjects.....http://www.natap.org/2013/EACS/EACS_38.htm
UPBEAT CROI 2013: HIV is an Independent Predictor of Lower Bone Mineral Density in HIV-positive Subjects Compared to HIV-negative Subjects.....http://www.natap.org/2013/CROI/croi_200.htm
CROI 2015, February 23-26, 2015, Seattle, Washington
Mark Mascolini
Bone mineral density (BMD) did not decline more over time in adults with versus without HIV in a 3-year study of a Dublin cohort [1]. BMD dropped more in people who recently started antiretroviral therapy, but no specific antiretrovirals--including tenofovir--predicted waning BMD.
Previous research showed that BMD ebbs after people start antiretroviral therapy, observed Willard Tinago and University College Dublin colleagues. But little is known about whether BMD changes over time differ between people with and without HIV. To address that question--and to identify predictors of BMD change in people with HIV--the Dublin team conducted this prospective cohort study.
The study cohort, UPBEAT, enrolled HIV-positive people from Mater Misericordiae University Hospital in Dublin and HIV-negative people from the greater Dublin general population. Cohort members had DXA scans at the femoral neck, total hip, and lumbar spine when they entered the cohort and every year for 3 years. The investigators also collected demographic, clinical, and medication data--plus fasting blood samples focused on bone markers. They used longitudinal mixed models to compare rates of absolute change in BMD in the whole cohort and within the HIV group.
Of the 474 people who completed the baseline visit, 210 (44%) had HIV infection. Follow-up analyses included 384 people, 176 of them (46%) with HIV. Of these 384 people, 120 had two annual BMD measurements and 264 had three. In the follow-up group, people with HIV were significantly younger than HIV-negative cohort members (median 39 versus 43, P = 0.04). The HIV group included a higher proportion of men (61% versus 46%, P = 0.003), a lower proportion of whites (61% versus 81%, P < 0.001), and a higher proportion of current smokers (34% versus 15%, P < 0.001). Among people with HIV, 88% were taking antiretroviral therapy, 73% were taking tenofovir, and median CD4 count stood at 508.
Compared with the HIV-negative group, people with HIV had significantly lower baseline median BMD at the femoral neck (1.024 versus 1.055 g/cm2, P = 0.003), total hip (1.061 versus 1.107 g/cm2, P = 0.003), and lumbar spine (1.164 versus 1.238, P = 0.001). The investigators reported earlier that HIV infection was independently associated with lower BMD at the femoral neck, total hip, and lumbar spine after statistical adjustment for demographics, lifestyle factors, body mass index, and bone biomarkers [2].
In the whole cohort BMD dropped 0.43% yearly at the femoral neck (P < 0.001), 0.41% yearly at the total hip (P < 0.001), and 0.28% yearly at the lumbar spine (P = 0.014). Respective yearly declines in people with HIV were 0.6% (P = 0.001), 0.44% (P < 0.001), and 0.22% (not significant, P = 0.22). Respective yearly drops in the HIV-negative group were 0.27% (P = 0.025), 0.35% (P < 0.001), and 0.34% (not significant, P = 0.08). Absolute change in BMD over time did not differ significantly between people with and without HIV, even after adjustment for age, gender, ethnicity, smoking status, and body mass index.
Focusing only on people with HIV, the UPBEAT investigators determined that starting antiretroviral therapy less than 3 months before entering the cohort or during the study was independently associated with greater drops in BMD at all three sites assessed. Being older than 30, being Caucasian, or not taking antiretroviral therapy during follow-up independently predicted greater BMD waning at the femoral neck, but not at the total hip or lumbar spine. Higher baseline parathyroid hormone independently predicted a smaller drop in BMD at the femoral neck. (Parathyroid hormone controls calcium levels in blood and thus calcium levels--and BMD--in bone.) Change in BMD was not associated with current or cumulative use of tenofovir or protease inhibitors, or with CD4 count, gender, current smoking, vitamin D, or body mass index.
"Although those with HIV have lower BMD" at baseline, the researchers concluded, "we observed no difference in rate of BMD loss between groups over time."
References
1. Tinago W, Cotter A, Macken A, et al. Predictors of longitudinal change in bone mineral density in a cohort of HIV positive and negative subjects. CROI 2015. February 23-26, 2015. Seattle, Washington. Abstract 774.
2. Cotter AG, Sabin CA, Simelane S, et al. Relative contribution of HIV infection, demographics and body mass index to bone mineral density. AIDS. 2014;28:2051-2060.
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Reported by Jules Levin
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