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Classic characteristics of old age associated with poor physical function in middle-aged people living with HIV
Michael Carter, 2013-02-20 07:10:00
Impaired physical function in middle-aged people living with HIV is associated with low reduced muscle mass, reduced bone mineral density and hormonal changes, according to research conducted in the United States and published in the online edition of the Journal of Acquired Immune Deficiency Syndromes. These are similar to the factors associated with frailty among elderly patients in the general population. The investigators stress the importance of improving muscle and bone mass and boosting certain hormone levels in people with lower physical functioning.
Thanks to antiretroviral therapy, the prognosis of many people living with HIV is now excellent. Nevertheless, there is some evidence that people with HIV may experience premature or accelerated ageing and be vulnerable at an early age to the diseases of old age.
In the general population, ageing is accompanied by reductions in muscle mass, accumulation of visceral and subcutaneous fat, loss of strength and low bone mineral density. Hormonal changes also have a role in the ageing process, including lower production of insulin-like growth factor (IGF)-1 and IGF binding protein-3 (IGFBP-3).
Investigators at the University of Colorado Hospital wanted to assess the relationship between these classic indicators of ageing and functional capacity in middle-aged people with HIV.
The study involved people aged between 45 and 65 years. All were taking antiretroviral therapy and had a viral load below 200 copies/ml.
A range of tests was used to assess the physical function of the study participants. The investigators matched 33 people with low physical function with 48 high-function control patients of the same sex, similar age and comparable duration of infection with HIV.
Overall, the participants had a mean age of 53 years, mean CD4 cell count was approximately 600 cells/mm3 and 96% had a viral load below 50 copies/ml.
However, there were significant differences between those with low physical function and those with higher function.
People with low physical function were more likely to be smokers (50 vs 12%; p = 0.012) than those with high levels of physical function. They also had lower nadir (lowest ever) CD4 cell counts (106 vs 179 cells/mm3; p = 0.028), were more likely to report chronic pain (68 vs 8%; p < 0.001) and had a higher VACS Index score (an indicator of poor prognosis, p = 0.001) than people in the control group.
A fifth of people with low function were classified as obese, compared to 13% of higher functioning patients. Participants with low physical function were significantly more likely to have low levels of lean muscle mass than the control group (OR = 2.5; 95% CI, 1.0-6.1; p = 0.04). A low body mass index (BMI) was also predictive of poor physical function (OR = 1.7; 95% CI, 1.2-2.2; p < 0.001).
Rates of osteopenia or osteoporosis in the hip were significantly higher among the people with low physical function than those with higher functioning (68 vs 33%; p = 0.01). Moreover, 67% of people with low function had reduced bone mineral density in the lumbar spine compared to 38% of the controls (p = 0.02).
Lower T-scores at the hip (OR = 3.8; 95% CI, 1.1-12.5; p = 0.028) and lumbar spine (OR. 2.3; 95% CI, 1.1-4.5; p = 0.022), together with lower bone mineral density in the lumbar spine (OR = 2.1; 95% CI, 1.1-4.0; p = 0.023) and hip (OR = 2.4; 95% CI, 1.1-5.6; p = 0.032) were all significantly associated with low physical function.
The investigators believe these findings point towards “a significant increase in fracture risk among low functioning persons.” They stress the importance of “evaluating, monitoring, and modifying risks for both falls and bone fragility to prevent fractures among persons ageing with HIV.”
Low function was also associated with reductions in IGF-1 (OR = 5.0; 95% CI, 1.4-20.00; p = 0.015) and IGFBP-3 (OR = 3.3; 95 CI, 1.7-9.9; p = 0.002).
Indeed, levels of IGF-1 observed in people with low function were similar to those seen in healthy men in the general population aged between 70 to 80 years, or frail women in their 70s.
“Our findings indicate that functional impairment in middle-aged adults with HIV-1 infection is associated with low muscle mass, bone mineral density, IGF-1, and IGFBP-3,” the investigators conclude. “Further studies should investigate the impact of interventions to increase bone, muscle, or IGF-1 on functional capacity among persons ageing with HIV infection.”
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