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Peak Bone Mass Lower in Young HIV+ vs HIV- Men--and Bone Structure Abnormal
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20th Conference on Retroviruses and Opportunistic Infections, March 3-6, 2013, Atlanta
"men infected with HIV early in life appear to have increased bone turnover and achieve lower peak bone mass that is accompanied by markedly abnormal bone microstructure and significantly decreased estimated bone strength.....The researchers believe these deficits heighten the risk of fracture as young HIV-positive men grow older"
Mark Mascolini
HIV-positive men in their 20s had lower peak bone mass than a comparison group of HIV-negative men in a US study [1]. High-resolution peripheral quantitative CT (HRpQCT) detected "markedly abnormal" bone architecture in the young men with HIV. Men infected with HIV perinatally or in adolescence did not differ in these measures.
Michael Yin (Columbia University, New York) and colleagues noted that men typically attain more than 90% of peak bone mass by the time they are 20 to 25. Because HIV and antiretroviral therapy can affect bone mineral density, and because HIV acquired early in life "may interfere with acquisition of genetically determined peak bone mass," they conducted this comparison of young HIV-positive and negative black or Hispanic men.
The analysis relied on DXA scans, which measure areal bone mineral density (aBMD), and HRpQCT, which measures true cortical and trabecular volumetric BMD (vBMD) and microarchitecture. DXA, the investigators explained, "measures only the amount of bone present and may be confounded by bone size and growth."
The study involved 30 HIV-positive and 15 HIV-negative black or Hispanic men from 20 to 25 years old, all at Tanner stage 5. The investigators excluded men with a history of fragility fracture of osteoporosis, endocrinopathies, renal insufficiency, or use of glucocorticoids or antiepileptics. Half of the HIV-positive men were infected perinatally, and half were infected during adolescence. All men with HIV were taking antiretrovirals.
Perinatally infected men had an average nadir CD4 count of 191 and an average current count of 474. Average nadir and current CD4 counts in men infected during adolescence were 299 and 533. The perinatally infected men had been taking antiretrovirals of an average 12 years; men infected during adolescence had been diagnosed for an average 2.5 years and on therapy for an average 2 years. Two thirds of perinatally infected men were taking a protease inhibitor regimen, and 87% of the other men were taking a nonnucleoside regimen.
Age averaged 22.5 in the HIV group and 22.0 in the HIV-negative group. Most HIV-positive men (60%) were black, while 80% of HIV-negative men were Hispanic. Mean body mass index was similar with and without HIV (26 and 25 kg/m(2)).
Lumbar spine, distal radius, femoral neck, and total hip aBMD were all lower in men with HIV; these differences were significant for lumbar spine (P = 0.049) and distal radius (P = 0.01) and nearly significant for femoral neck (P = 0.07) and total hip (P = 0.09). Age-, sex-, and ethnicity-standardized z scores at all four sites were significantly lower (by 0.4 to 1.3 standard deviation) in young men with HIV (Table 1 in poster link below).
HRpQCT recorded 6% to 19% lower vBMD, trabecular vBMD, and cortical and trabecular thickness at the radius and tibia in young men with HIV (Table 2 in poster link below). These measures did not differ significantly between HIV-positive men infected perinatally and those infected during adolescence. Total and trabecular vBMD, and trabecular and cortical thickness, remained significantly lower in men with HIV after statistical adjustment for race/ethnicity.
Bone analysis by Individual Trabecular Segmentation showed that the plate-to-rod ratio, trabecular plate volume, and number, thickness, and plate-rod and plate-plate junction densities were 4% to 32% lower in men with HIV. Micro Finite Element Analysis found that trabecular stiffness was 24% lower at the radius and whole-bone stiffness was 17% lower at the radius and 14% lower at the tibia in HIV-positive men.
Together these findings led Yin and colleagues to conclude that "men infected with HIV early in life appear to have increased bone turnover and achieve lower peak bone mass that is accompanied by markedly abnormal bone microstructure and significantly decreased estimated bone strength."
Differences between HIV-positive and negative men in trabecular and cortical microarchitecture "were similar in magnitude to those reported in postmenopausal women with and without fractures."
The researchers believe these deficits heighten the risk of fracture as young HIV-positive men grow older.
Reference
1. Yin M, Broun E, J Shah J, et al. Lower peak bone mass and abnormal trabecular and cortical microarchitecture in men infected with HIV early in life. 20th Conference on Retroviruses and Opportunistic Infections. March 3-6, 2013. Atlanta. Abstract 818. http://www.retroconference.org/2013b/PDFs/818.pdf.
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