Falls affect 30% to 40% of community-living adults over age 65 every year. Half of falls result in some type of injury, and falls may contribute to declining function, loss of independence, illness, and death (1). Fall-related health care costs the United States nearly $30 billion annually (2). For many older adults, fear of falls and their physical and psychological aftermath are a serious concern, often leading to self-imposed restrictions on activity (3,4).

Fall prevention research has found that regular physical activity incorporating strength and balance exercise can reduce falls, fall-related injuries, and falls resulting in medical care (5–7). Community-based programs intended to enhance older adults’ access to age-appropriate exercise may be beneficial in preventing falls. In a large integrated health system in Washington State, Group Health Cooperative (GHC), Medicare-qualifying adult members aged 65 or older are eligible to participate in 2 nationally disseminated exercise programs at no additional cost. EnhanceFitness (EF), an evidence-based intervention funded by the Centers for Disease Control and Prevention, offers community-based group exercise classes led by qualified instructors. Another program, Silver Sneakers (SS), provides full membership to participating fitness centers nationwide in more than 10,000 locations (8,9). Previous investigations have suggested that specific fall prevention exercise programs can be effective in preventing falls among community-dwelling older adults (10,11). However, these programs targeted fall prevention and were not as widely disseminated as EF and SS are. Although general exercise programs for older adults reach a much wider audience, their impact on fall prevention has not been studied. Although EF participation has been shown to improve physical function (12,13), no previous studies have examined associations between participation in either EF or SS and fall-related outcomes (14). Preventing falls and the costs and system burden they create is a relevant outcome from both the societal and health plan perspectives.

Our objective was to examine the relationship between participation in EF or SS and risk for a fall requiring medical treatment (termed “medical fall” hereafter), in a sample of GHC Medicare plan enrollees. On the basis of existing evidence that physical activity plays an important role in fall prevention, we hypothesized that consistent users of either program would have lower risks of a medical fall compared with nonusers.

Compared with nonusers, consistent and intermittent users of either program were more likely to be female, less likely to smoke, and had lower Charlson comorbidity scores (Tables 1 and 2). However, all users of either EF or SS were more likely to have had a diagnosis for osteoarthritis, osteoporosis, visual impairment, and musculoskeletal conditions during the study period, whereas consistent users of either EF or SS were less likely to use sedatives or sleeping medications compared with nonusers and intermittent users of either program. EF users had a mean attendance of 65 times in the year (median of 67), while SS users’ mean attendance was 51 times in 2011 (median of 33). Survival curves (Figure) suggest that consistent EF users had the greatest proportion of the sample remaining without a medical fall at the end of the study period, followed by intermittent EF users, and, finally, nonusers. Both consistent and intermittent SS groups had similar curves, with both showing reduced time to falls compared with the nonuser group.

In hierarchically adjusted Cox regression models (Table 3), a decreased risk of medical fall was found for both consistent and intermittent users of EF compared with nonusers, after adjusting for demographics. The same pattern remained in the fully adjusted model, showing consistent EF users to have a 26% decreased risk of a medical fall compared with nonusers, whereas intermittent EF users had a 13% decreased risk. The demographic model for SS use indicated a significant reduction for consistent and intermittent users. However, the full model yielded similar results for intermittent users (7% decrease in fall risk) but not for consistent SS users.

To our knowledge, this is the first study to directly investigate the impact on the risk of medical falls of 2 exercise programs not specific to fall prevention. Consistent use of EF, our proxy for regular participation in the program over several years, was associated with the greatest reduction in risk of a medical fall, lowering risk by 20% to 30%. However, even intermittent use of the EF program also decreased the risk of medical falls. Although this finding corroborates previous evidence suggesting that strength and balance exercises, major components of the EF program, are essential to reducing fall and fall injury risk in older adults (5,21,22), further investigation involving more precise measure and categorization of participation is needed.

The results were less clear for the impact of the SS program. Unadjusted findings were suggestive of moderate risk reduction, but full adjustment yielded significant reduction only for intermittent users. This risk reduction was smaller than those seen for EF but was in the range of a 10% to 15% reduction in medical falls. However, the finding of significant impacts only for intermittent users runs counter to established findings in the literature, which suggest that consistent physical activity yields the strongest health impacts (5–7). This result makes drawing conclusions challenging and suggests that misclassification may be obscuring accurate interpretation of SS analyses.

Despite these limitations in the SS analysis, the magnitude of the association observed for SS participants was smaller than that seen with EF, a more structured program that includes balance and strength exercises that research suggests are critical to reducing fall risk (23). Because of the unstructured nature of the SS program in which participants can use whatever gym equipment or attend any classes they wish, we know very little about the type or intensity of exercise that participants engaged in or whether balance or strength exercises were performed. It is likely that balance exercises were not routinely practiced, as evidence suggests that most older adults do not engage in balance exercise (24,25). This likelihood may be part of the reason we did not see stronger associations between SS use and fall prevention.

EF has routinely scheduled classes multiple times per week and a strong social environment, promoting regular attendance at the EF program over many years. Users of the more free-form and independently driven SS program may be more likely to vary in the amount of use. On the basis of data supplied by each program, aggregate use statistics for this sample in 2011 support this differential attendance pattern. This finding suggests not only that EF users tend to use the program more frequently but also that the use pattern in the sample is more normally distributed (meaning that SS may have few very frequent users skewing the mean use statistic). This differential usage pattern may make the consistent and intermittent categories created for our analyses more problematic for SS, as the consistent category would be less likely to strongly parallel regular use. In short, although these results suggest that the EF program is more successful in reducing the risk of medical falls for this population, the nature of SS as an independently driven program with more sporadic attendance patterns lends itself more to misclassification under the participation definitions used in these analyses and makes conclusions about the program’s association with fall-related outcomes less robust.

This study has several limitations. First, it focuses only on falls resulting in medical care, as these appear in the inpatient or outpatient medical record, making it possible to measure without the use of self-report. This outcome definition excludes fall cases for which people do not seek medical attention and any injury truly due to a fall but not reported (and thus not coded) as such in the medical record. Despite this limitation, falls resulting in medical care are of high priority for risk reduction efforts given their adverse personal and societal effects (26,27).

Although missing data were not an issue for the outcome of interest, some data were missing for certain covariates, primarily race and BMI. Though these missing data resulted in small reductions in sample size for full adjustment models, they are not believed to have limited power. Participation in EF and SS is voluntary and, therefore, inherently self-selected. People who choose to participate in these programs may be systematically different from those who do not in ways that may affect their fall risk. Therefore, the potential for residual confounding remains. No information about engagement in physical activity outside either program was available for users or nonusers. The inability to adjust for baseline physical activity level in either group is a limitation; however, only 6% to 25% of older adults are estimated to regularly engage in the balance training and muscle-strengthening exercises requisite to fall risk reduction (28,29), suggesting that the impact of outside physical activity is likely low. Additionally, the threshold for participation in a given year was only 2 uses in that year, which is not indicative of regular physical activity through these programs. Although this finding limits our conclusions to the impact of 2 or more program uses per year, the low cut point used may have minimized the exposure of the group as a whole. This type of exposure misclassification would be expected to attenuate any association, rather than inflate it, so our results may be conservative. Future investigations should aim to use a continuous measure of participation to address this issue.

Despite these limitations, this study has several strengths. First, all outcomes and comorbidities were based on ICD-9-CM codes in the medical record rather than self-report. This procedure greatly reduces the potential for misclassification of comorbidity and outcome status, lending itself to a higher degree of accuracy in risk estimates. Furthermore, the use of this administrative data allowed for adjustment of many fall-related comorbidities that can be difficult to capture, including a history of gait and balance problems. Additionally, these analyses were based on a large, demographically representative sample, increasing power to detect associations and maximizing the generalizability of findings.

The results of this analysis provide evidence that participation in EF is associated with a reduced risk of medical falls. Furthermore, as hypothesized, this relationship shows a consistent pattern in which the strongest protective association was for consistent users of the program. Participation in SS may provide a moderate degree of fall protection, although findings were inconclusive. Overall, results suggest that evidence-based physical activity programs, particularly EF, should be more widely disseminated into communities not only for their general effects on fitness but also for their likely benefits on prevention of fall-related health care use, an important personal and societal outcome.