To the Editor: Falls are the leading cause of unintentional injury and injury death in older adults.1 Although exercise-based fall-prevention interventions are demonstrably effective, reducing falls by approximately 30%,2 in the absence of advances, their effect may diminish given the ever-growing population of older adults. Trips represent the primary cause of falls by community-dwelling older adults,3, 4 so complementing exercise-based interventions with ones specifically targeting trip-related falls may significantly improve effectiveness. It was recently shown that a trip-specific training protocol reduced falls by 86% after laboratory-induced trips.5 It was hypothesized that a similar trip-specific training protocol would significantly reduce trip-related falls in the community. Two hundred ten community-dwelling women contacted investigators to volunteer for participation. Women were targeted because of their higher fall rate.3 Thirteen women were excluded for use of ambulatory assistive devices, lower extremity joint replacement, spinal fusion, or being younger than 55. The subjects provided written consent to participate in this institutional review board–approved study before being screened for cognitive, endocrine, musculoskeletal, or neurological disorders that might limit participation, including proximal femur bone density less than 0.61 g/cm2 One hundred seventy women were quasirandomly assigned (alternating allocation according to screening date after stratifying age according to decades) to a control or training group. Six women assigned to the latter failed to schedule training and were withdrawn. Training consisted of four 1-hour sessions over 2 weeks during which subjects practiced recovering from large treadmill-delivered postural disturbances serving as trip surrogates.5 Two subjects withdrew before completing all training sessions, and 82 completed training (n = 80 control; Table 1). Every 2 weeks for 1 year, subjects responded to postcards or e-mails asking whether they had fallen (come to rest inadvertently on the ground or other lower level) or stumbled (lost balance but did not fall) during the previous 2 weeks. If so, a follow-up telephone interview was conducted to discuss responses to a previously distributed survey to determine whether the event was a fall or stumble and trip-related (caused by the ground or obstacle obstructing motion of the swing limb) or not. If the subject explicitly stated that compensatory step-initiation was impossible (e.g., both feet entwined by a leash), the fall was deemed “unlikely preventable.” Otherwise, if a majority of five blinded investigators independently voted “more times than not an average young adult would fall during similar circumstances,” (e.g., slipping on black ice while power-walking), the fall was also deemed “unlikely-preventable.” Use of surveys and a short time between fall and follow-up probably improved recall and minimized underrepresentation of falls.6 Two control subjects and one training subject were withdrawn (after 6.5, 11, and 10 months, respectively) after surgeries that would have initially excluded participation. The incidence rate ratio (IRR) of avoidable trip-related falls, trip-related stumbles, and avoidable non-trip-related falls (per person-year) and the corresponding 95% confidence intervals (CIs) were calculated using a Poisson regression in SPSS (SPSS IBM, Chicago, IL). Significance was set at α ≤.05. Table 1 summarizes sociodemographic characteristics, falls, and stumbles. Training significantly reduced trip-related fall rates. Controls had 0.39 trip-related falls per person-year and trained women had 0.21 (IRR = 0.54, 95% CI = 0.30–0.97, P = .04). Differences in trip-related stumbling rates did not explain these differences: 1.21 trip-related stumbles per person-year in controls and 1.0 in trained women (IRR = 0.82, 95% CI = 0.62–1.11, P = .20). There was no significant difference in the number of non-trip-related avoidable falls between groups (IRR = 0.95, P = .83). Avoiding a fall after a trip is a complex, whole-body motor skill requiring coordination of the trunk and lower extremities over a brief period.7 The “specificity of learning hypothesis” suggests that this motor skill is best learned when practice conditions closely resemble those of an actual trip.8 Common exercise interventions (e.g., resistance and balance training) do not mimic the environmental and sensorimotor conditions of a trip or the subsequent recovery. In contrast, the large degree of similarity between trip recovery in the community and during a treadmill-delivered surrogate5 probably explains the approximately 50% reduction in trip-related falls, even after just a short-term intervention. This seems extremely promising as a means of complementing the average reductions of 29% to 32% in all-cause fall rates after multicomponent exercise programs that require many months to complete,2 but further study is needed. The generalizability of results to men and less-healthy older adults remains to be determined, although similar results may be anticipated.9 In conclusion, the motor skill of avoiding a trip-related fall is efficiently and effectively improved with short-term, skill-specific training, which represents a departure from conventional fall-prevention interventions. Conflict of Interest: This work was supported by Centers for Disease Control and Prevention Grant R01CE001430. A report using preliminary data from this manuscript was presented at the 63rd Annual Scientific Meeting of the Gerontological Society of America, 2010. The abstract can be found in Transitions of Care Across the Aging Continuum. Abstracts of the 63rd Annual Scientific Meeting of the Gerontological Society of America. November 19–23, 2010. New Orleans, Louisiana, USA. Gerontologist 2010; 50 Suppl 1:1–571. Dr. Grabiner reports receipt of research grants from the Centers for Disease Control and Prevention. The University of Illinois at Chicago owns a patent on some of the technology used in the ActiveStep system and consequently there is an institutional conflict of interest. Dr. Grabiner is an inventor of the ActiveStep system but has no conflicts of interest to declare with regard to the present study. Author Contributions: Study concept and design: Grabiner, Rosenblatt. Acquisition of data: Rosenblatt. Analysis and interpretation of data: Grabiner, Rosenblatt, Marone. Drafting of the manuscript: Grabiner, Rosenblatt. Critical revision of the manuscript for important intellectual content: Marone. Statistical analysis: Rosenblatt. Obtained funding: Grabiner. Sponsor's Role: The Centers for Disease Control and Prevention had no role in the design and conduct of the study; in the collection, analysis, and interpretation of the data; or in the preparation, review, or approval of the manuscript.
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Rosenblatt et al. (2013) studied this question.