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Poor balance confidence--not physical
function--predicts falls in older men with HIV
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"HIV group had a significantly higher rate of falls with fracture (3.3% versus 0.7%, P = 0.02)."
CROI 2015, February 23-26, 2015, Seattle, Washington
Mark Mascolini
Poor balance confidence measured by a standard test quadrupled the odds of falls in 50- to 79-year-old HIV-positive men in the Multicenter AIDS Cohort Study (MACS) [1]. But balance and physical function assessed by standard tests in these men did not predict falls. In a combined analysis of HIV-positive and negative older MACS men, poor balance confidence doubled the odds of falling.
Risk of falling rises with age and poses a special threat to people with low bone mineral density, including many with HIV infection. Todd Brown and MACS colleagues observed that HIV-positive people have multiple fall risks, including polypharmacy, neuropathy, cognitive decline, and low muscle mass. The MACS team noted that simple tests of physical function and balance confidence predict falls in the general population, but whether these tools predict falls in older people with HIV remained uncertain.
To find out, Brown and colleagues conducted the MACS Bone Strength Substudy (BOSS) in HIV-positive and negative MACS members 50 to 79 years year. All men with HIV had a viral load below 200 copies. With the Activities Balance Confidence (ABC) scale [2], all BOSS participants rated their balance confidence from 0% to 100% on 16 activities, ranging from walking around the house to standing on a chair to reach and walking on icy sidewalks. The researchers calculated average confidence on each item with cutoffs of above 80% and above 90% indicating good balance.
Participants also completed two standard tests of balance, two tests of strength, a walk speed test, and a composite physical function tool, the Short Physical Performance Battery. To test balance, the MACS team used (1) the standing balance test, in which men stood for 30 seconds with feet in four different positions of increasing difficulty: side-by-side, semi-tandem, tandem, and one-leg stand, and (2) the functional reach test, in which men stood next to a wall then reached forward as far as possible by shifting weight on their feet.
In the 2 years after the first substudy visit, MACS men reported any fall. They were grouped into three clusters, no falls, fallers (at least one fall), and recurrent faller (more than one fall). The MACS team used logistic regression to look for links between balance confidence or physical function tests and falling status, with statistical adjustment for age, race, education, body mass index, MACS site, and HIV status.
The analysis included 239 men with HIV and 298 without HIV who had about 14.7 months of follow-up. Age averaged 60.4 in the HIV group and 61.6 in the HIV-negative group (P < 0.0001), and the HIV group included a significantly higher proportion of African Americans (24.7% versus 13.8%, P = 0.005).
About 91% of both the HIV-positive and negative groups had greater than 80% balance confidence on all 16 balance items, and about 81% in each group had greater than 80% confidence on 6 balance items selected by the investigators. The HIV and no-HIV groups did not differ in any measurement of balance, strength, speed, or composite physical function.
During follow-up a slightly but nonsignificantly higher proportion of men with HIV fell (27.2% versus 23.7%, P = 0.28). The groups did not differ in rates of 2 falls or falls with an injury. But the HIV group had a significantly higher rate of falls with fracture (3.3% versus 0.7%, P = 0.02).
No tests of balance, strength, speed, or composite physical function predicted having 1 or more fall in the combined group of men with and without HIV or in only the group with HIV. There were trends toward slower gait speed predicting 1 or more or 2 or 2 or more falls in men with HIV. Most of the four balance confidence assessments predicted 1 or more falls or 2 or more falls in both the combined HIV+/HIV- group and in HIV-positive men alone. Adjusted odds ratios (aOR) for 1 or more falls (and 95% confidence intervals) follow:
Men with and without HIV, 1 or more falls:
Total balance confidence ≤80% vs > 80%: aOR 1.54 (0.78 to 3.04), P = 0.209
Total balance confidence ≤90% vs > 90%: aOR 2.1 (1.32 to 3.34), P = 0.002
6-item balance confidence ≤80% vs > 80%: aOR 2.24 (1.38 to 3.66), P = 0.001
6-item balance confidence ≤90% vs > 90%: aOR 1.69 (1.11 to 2.57), P = 0.014
Men with HIV, 1 or more falls:
Total balance confidence ≤80% vs > 80%: aOR 2.32 (0.81 to 6.66), P = 0.118
Total balance confidence ≤90% vs > 90%: aOR 4.15 (1.96 to 8.78), P = 0.000
6-item balance confidence ≤80% vs > 80%: aOR 4.25 (1.93 to 9.35), P = 0.000
6-item balance confidence ≤90% vs > 90%: aOR 2.86 (1.48 to 5.5), P = 0.002
The MACS team suggests that the "Activities Balance Questionnaire could be useful in clinic to identify HIV-infected patients at greater risk of falls." Notably, poor balance confidence but not test-measured balance itself predicted falls in these older men with and without HIV.
References
1. Brown TT, Li X, Jacobson LP, et al. Balance confidence predicts falls better than physical function testing in HIV+ men. CROI 2015. February 23-26, 2015. Seattle, Washington. Abstract 786.
2. Powell LE, Myers AM. The Activities-specific Balance Confidence (ABC) Scale. J Gerontol Med Sci. 1995;50:M28-M34.
http://www.pacificbalancecenter.com/forms/abc_scale.pdf
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