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.
Acknowledgments
There was no financial support available for this work. Analyses
were performed on an existing data set within the Group Health
Research Institute.