Effect of structured physical activity on prevention of serious fall injuries in adults aged 70-89: randomized clinical trial (LIFE Study)

Abstract

Objective: To test whether a long term, structured physical activity program compared with a health education program reduces the risk of serious fall injuries among sedentary older people with functional limitations.

Design: Multicenter, single blinded randomized trial (Lifestyle Interventions and Independence for Elders (LIFE) study).

Setting: Eight centers across the United States, February 2010 to December 2011.

Participants: 1635 sedentary adults aged 70-89 years with functional limitations, defined as a short physical performance battery score ≤ 9, but who were able to walk 400 m.

Interventions: A permuted block algorithm stratified by field center and sex was used to allocate interventions. Participants were randomized to a structured, moderate intensity physical activity program (n=818) conducted in a center (twice a week) and at home (3-4 times a week) that included aerobic, strength, flexibility, and balance training activities, or to a health education program (n=817) consisting of workshops on topics relevant to older people and upper extremity stretching exercises.

Main outcome measures: Serious fall injuries, defined as a fall that resulted in a clinical, non-vertebral fracture or that led to a hospital admission for another serious injury, was a prespecified secondary outcome in the LIFE Study. Outcomes were assessed every six months for up to 42 months by staff masked to intervention assignment. All participants were included in the analysis.

Results: Over a median follow-up of 2.6 years, a serious fall injury was experienced by 75 (9.2%) participants in the physical activity group and 84 (10.3%) in the health education group (hazard ratio 0.90, 95% confidence interval 0.66 to 1.23; P=0.52). These results were consistent across several subgroups, including sex. However, in analyses that were not prespecified, sex specific differences were observed for rates of all serious fall injuries (rate ratio 0.54, 95% confidence interval 0.31 to 0.95 in men; 1.07, 0.75 to 1.53 in women; P=0.043 for interaction), fall related fractures (0.47, 0.25 to 0.86 in men; 1.12, 0.77 to 1.64 in women; P=0.017 for interaction), and fall related hospital admissions (0.41, 0.19 to 0.89 in men; 1.10, 0.65 to 1.88 in women; P=0.039 for interaction).

Conclusions: In this trial, which was underpowered to detect small, but possibly important reductions in serious fall injuries, a structured physical activity program compared with a health education program did not reduce the risk of serious fall injuries among sedentary older people with functional limitations. These null results were accompanied by suggestive evidence that the physical activity program may reduce the rate of fall related fractures and hospital admissions in men.Trial registration ClinicalsTrials.gov NCT01072500.

Fig 1 Effect of a moderate physical activity intervention on time to first serious fall injury. Outcomes represent the cumulative number of participants with a serious fall injury. The adjusted hazard ratio was obtained from a proportional hazards regression model that stratified the baseline hazard by sex. Curves were truncated at three years because of the small number of subsequent outcomes and people at risk. See table 2 for numbers of all outcomes through the end of follow-up (3.5 years). Duration of follow-up differed because participants were recruited over a 21 month period, but follow-up ended for all participants in December 2013

Fig 2 Hazard ratios for time to first serious fall injury for physical activity versus health education according to subgroups. Age, sex, ethnicity/race, and baseline physical performance were prespecified in the analysis plan, whereas fall in past year was not. With the exception of the analysis for the sex subgroup effect, the adjusted hazard ratios were obtained from proportional hazards regression models that stratified the baseline hazard by sex. SPPB=short physical performance battery. P values were obtained from likelihood ratios tests of the interaction terms added to the proportional hazards regression model

Fig 3 Effect of a moderate physical activity intervention on time to first serious fall injury in men and women. Outcomes represent the cumulative number of participants with a serious fall injury. Adjusted hazard ratios were obtained from proportional hazards regression models that included sex, intervention, and sex×intervention terms (that is, sex was not used as a factor to stratify the baseline hazard). The curves were truncated at three years because of the small number of subsequent outcomes and persons at risk. The numbers of all outcomes through the end of follow-up (3.5 years) are reported in appendix table 1