Physical activity to prevent disability in the elderly

I’ve been so down on diet recently, that I thought I’d talk about exercise for once. “Effect of Structured Physical Activity on Prevention of Major Mobility Disability in Older Adults: The LIFE Study Randomized Clinical Trial“:

Importance: In older adults reduced mobility is common and is an independent risk factor for morbidity, hospitalization, disability, and mortality. Limited evidence suggests that physical activity may help prevent mobility disability; however, there are no definitive clinical trials examining whether physical activity prevents or delays mobility disability.

Objective: To test the hypothesis that a long-term structured physical activity program is more effective than a health education program (also referred to as a successful aging program) in reducing the risk of major mobility disability.

Design, Setting, and Participants: The Lifestyle Interventions and Independence for Elders (LIFE) study was a multicenter, randomized trial that enrolled participants between February 2010 and December 2011, who participated for an average of 2.6 years. Follow-up ended in December 2013. Outcome assessors were blinded to the intervention assignment. Participants were recruited from urban, suburban, and rural communities at 8 centers throughout the United States. We randomized a volunteer sample of 1635 sedentary men and women aged 70 to 89 years who had physical limitations, defined as a score on the Short Physical Performance Battery of 9 or below, but were able to walk 400 m.

Interventions: Participants were randomized to a structured, moderate-intensity physical activity program (n = 818) conducted in a center (twice/wk) and at home (3-4 times/wk) that included aerobic, resistance, and flexibility training activities or to a health education program (n = 817) consisting of workshops on topics relevant to older adults and upper extremity stretching exercises.

Main Outcomes and Measures: The primary outcome was major mobility disability objectively defined by loss of ability to walk 400 m.

Results: Incident major mobility disability occurred in 30.1% (246 participants) of the physical activity group and 35.5% (290 participants) of the health education group (hazard ratio [HR], 0.82 [95% CI, 0.69-0.98], P = .03).Persistent mobility disability was experienced by 120 participants (14.7%) in the physical activity group and 162 participants (19.8%) in the health education group (HR, 0.72 [95% CI, 0.57-0.91]; P = .006). Serious adverse events were reported by 404 participants (49.4%) in the physical activity group and 373 participants (45.7%) in the health education group (risk ratio, 1.08 [95% CI, 0.98-1.20]).

Conclusions and Relevance: A structured, moderate-intensity physical activity program compared with a health education program reduced major mobility disability over 2.6 years among older adults at risk for disability. These findings suggest mobility benefit from such a program in vulnerable older adults.

This was a randomized controlled trial of people age 70-89 who had physical limitations, but could walk 400 m. One group was given a structured, moderate-intensity physical activity program twice a week at a center and 3-4 times a week at home. The other group got some health education, and was the control group. The main outcome of interest was a major mobility disorder, or the loss of the ability to walk 400m.

The good news is that this outcome was significantly less likely to occur in those who were in the exercise group. The incident rate of major mobility disability about two and a half years later was 35.5% in the control group and 30.1% in the intervention group. There was about a 5% increase in adverse events in the intervention group, but it wasn’t a statistically significant difference.

The bad news, though is that the number needed to treat was about 20. That means that you need to get 20 such people to engage in this program to prevent one from suffering the bad outcome. Nineteen of the twenty will see no benefit at all, with respect to major mobility disability.

I’m not in any way disparaging the results of this trial. I think it’s great. But we have here a high risk population, and a pretty intensive intervention. It’s important to recognize that even in this case, 95% of people who engage in this type of activity will not see the benefit promoted by this trial. I imagine that the benefits would be even less impressive in a lower risk population.

This is all to say that I think we might want to be a bit more realistic when we talk about the benefits of exercise. I think they are real, but we often sell it as a guarantee against a bad outcome. That may be far from true.


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