Surface Perturbation Training to Prevent Falls in Older Adults: A Highly Pragmatic, Randomized Controlled Trial

Lurie JD, Zagaria AB, Ellis L, et al. Surface perturbation training to prevent falls in older adults: a highly pragmatic, randomized controlled trial. Physical Therapy. 2020;100(7):1153-1162. doi:10.1093/ptj/pzaa023

Link to Original Article: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7498164/

Key Points

- Falls are a significant cause of injuries among older adults, and trips and slips are major contributors to falls.

- A study involving 506 high-risk older adults compared the effectiveness of adding surface perturbation training to the usual gait/balance training in reducing falls and fall-related injuries.

- The trial found that adding surface perturbation training significantly reduced the chance of fall-related injury at 3 months post-treatment, but did not show a significant reduction in the risk of any fall compared to the usual treatment.

- The study was a multi-center, pragmatic, randomized, comparative effectiveness trial conducted in outpatient physical therapy clinics.

- The perturbation training consisted of surface perturbation treadmill training integrated into multimodal exercise-based balance training compared to usual multimodal balance training alone.

- The addition of some surface perturbation training to usual physical therapy significantly reduced injurious falls up to 3 months post-treatment, prompting a need for further research to determine the optimal frequency, dose, progression, and duration of surface perturbation for this population.

Introduction

The research paper addresses the high prevalence and significant impact of falls among older adults in the United States. It highlights the substantial direct medical costs and overall financial burden associated with fall-related injuries, emphasizing the need for effective prevention strategies. Modifiable risk factors such as muscle weakness, balance problems, and environmental hazards are identified as key contributors to falls in this population. The paper discusses the effectiveness of multimodal exercise programs and evidence-based recommendations for fall prevention, emphasizing the importance of tailored progressive exercise to address balance, mobility, and lower extremity strength. Additionally, perturbation-based training, specifically the ActiveStep device, is introduced as a novel approach to improving reactions to postural perturbations and reducing the risk of falls among older adults. The paper emphasizes the potential of perturbation-based training in reducing falls, citing biomechanical studies and a pilot study that showed promising results, including a 60% reduction in injurious falls at 3 months. The main focus is on the design and objective of a large pragmatic trial to assess the comparative effectiveness of adding access to surface perturbation training to usual multimodal exercise-based balance training for reducing the risk of falls and fall-related injuries in high-risk older adults referred for physical therapy. The paper underscores the importance of evaluating the broad applicability and effectiveness of perturbation training in fall-prevention physical therapy for this clinical population.

Methods

Trial Design

The study described in the Trial Design section is a prospective, multi-center, highly pragmatic, randomized, comparative-effectiveness trial. Traditional randomized trials have limitations and may not adequately inform practice. Pragmatic trials, on the other hand, are designed to determine the effects of an intervention under usual conditions and can provide direct evidence for adoption into real-world practice. Patients completing informed consent were randomly assigned to perturbation training or usual treatment. The randomization procedures ensured allocation concealment, but blinding was not possible for the patients or clinicians. Treatment took place within routine clinical care at eight physical therapist outpatient practices in the northeast United States. The therapists had experience in providing gait and balance training but received no additional formal training for the trial. The number and content of therapy sessions, as well as the duration of treatment, were at the discretion of the therapist. The study aims to address the pragmatic question of whether giving physical therapists access to surface perturbation treadmill training as part of a comprehensive gait/balance training program improves patient outcomes. Following the treatment phase, study participants received a fall diary, which was prospectively completed.

Procedures

The Procedures section of the research paper describes the intervention provided to the treatment group, which received the usual gait/balance intervention available at their clinics. Patients underwent an individualized multimodal program tailored to their specific impairments, balance deficits, and functional limitations. The typical treatment regimen involved 2 to 3 sessions per week for 4 to 6 weeks, with each session lasting 45 minutes, although this varied based on individual needs. Common interventions included strengthening and flexibility exercises, balance exercises, mobility training, patient education, and home exercise programs. Home exercises were recommended 4 to 5 times per week or on days when patients did not attend the clinic and were progressed throughout the care period and post-therapy completion. The strength and flexibility exercises targeted patient-specific deficits, such as gastrocnemius/soleus stretching, heel/toe raises, chair sit-to-stand, and resistive exercises for hip and knee extension. Balance exercises aimed to improve postural alignment, sensory utilization for stability, anticipatory postural adjustments, and integration of sensory and motor strategies for functional balance and mobility. Finally, mobility training focused on enhancing stability during various walking tasks on different surfaces. These procedures were aimed at addressing patients' specific impairments and balance deficits while enhancing their overall functional mobility.

Surface Perturbation Treadmill Training

The Surface Perturbation Treadmill Training section of the research paper describes the training protocol used, involving sequential postural disturbances delivered while standing or walking on the ActiveStep device. The ActiveStep offers 5 levels of perturbations, ranging from slower, lower magnitude displacements to larger and faster displacements. The perturbation magnitude is determined by peak velocity, elapsed time to peak velocity, time during which peak velocity is maintained, and time required to decelerate the treadmill belt to zero velocity. The level of perturbations progressed based on patient performance, from less to more challenging. Perturbations occurred in forward (trip) and backward (slip) directions, with occasional use of sideways perturbations. Patients were instructed to maintain balance without taking a step or to take a step if needed, depending on the postural response trained. Therapists tailored perturbation conditions based on patient needs and previous performance. The training lasted approximately 15 minutes per session and was integrated into the overall treatment program. The pilot study showed that the average session duration was 44 minutes in the perturbation training group and 43 minutes in the usual treatment group. Treatment session length was not closely monitored in the large pragmatic trial.

Measures

The research paper's Measures section outlines the primary outcome measures and clinical measures used in the study. The main outcome measures focused on the proportion of participants experiencing falls and fall-related injuries over a year-long period, using definitions from the Centers for Disease Control and Prevention's Behavioral Risk Factor Surveillance System. Participants were provided with diaries to record falls. Clinical measures included the Timed Up & Go Test (TUG), Berg Balance Measure (BBS), Dynamic Gait Index (DGI), and Activities-specific Balance Confidence (ABC) Scale. These measures were collected at the beginning and end of treatment to assess gait and balance, predict fall risk, and identify high-risk patients for the trial. The study complied with recommendations to use multiple instruments due to the limited predictive value of any single measure. The collection of comorbidities, health history, and medication usage was also undertaken through chart review and patient self-report. These measures were obtained as part of routine clinical practice to identify high-risk patients, evaluate the similarity between the two groups in terms of fall risk, and assess potential interference with the effectiveness of the multi-modal treatment.

Study Population

The pragmatic trial described in the paper encompassed a diverse population of elderly individuals at risk of falling. Specifically, individuals aged 65 and above who were referred for gait/balance physical therapy at the participating sites were considered for inclusion. Eligibility for the study was determined through a baseline fall risk assessment and comprehensive examination by a therapist. To be considered eligible, participants needed to exhibit at least one of the specified fall risk factors, such as experiencing a fall in the previous year, Timed Up and Go (TUG) test taking longer than 13.5 seconds, Dynamic Gait Index (DGI) score of 19/24 or lower, Berg Balance Scale (BBS) score of 50/56 or lower, or Activities-specific Balance Confidence (ABC) scale score of less than 67%. For individuals diagnosed with Parkinson's disease, the thresholds for eligibility differed due to the reduced sensitivity of these instruments in predicting falls in this particular population. Patients with a primary concern related to positional vertigo or those with severe physical limitations that rendered them unsuitable for the treatments under study were excluded from the trial.

Statistical Analysis

The statistical analysis section of the research paper discusses the methodology, primary outcomes, and analysis plans of a clinical trial. The analyses were performed using SAS, with the primary outcome initially focused on the difference in fallers at 2 years. However, based on the pilot trial results, the primary outcomes and analysis plans were changed in 2013 to include the differences between treatment groups in the occurrence of falls and fall-related injuries after completing the clinic-based treatment program. Various statistical methods were used to analyze the data, including generalized linear mixed models, survival analysis, repeated-measures analysis of variance, and sample size calculations. The initial sample size calculation was based on reduction in fallers, and a subsequent calculation in 2013 found that 400 participants would be sufficient to assess a difference in injurious falls. Due to slower than expected recruitment, the final target enrollment for the trial was 500 to maintain sufficient power to assess fall risk within an attainable sample size. The paper emphasizes the importance of accurately reflecting protocol changes in trial registrations to align with the revised protocol. Adjusted analyses were also performed to account for characteristics associated with loss to follow-up. Overall, the statistical analysis section provides a comprehensive overview of the methodology and analytical approaches used to evaluate the primary outcomes of the clinical trial.

Results

Patients

A total of 506 patients were eligible for the study. 253 patients (50%) were randomized to perturbation training group and 253 (50%) were randomized to usual treatment group. The average number of treatments received was 10.4 sessions and 10.4 sessions for the perturbation training group and usual treatment group, respectively. At three months, 87% of the perturbation training group and 86% of the usual treatment achieved follow up. At one year, 76% of the perturbation training group and 78% of the usual treatment achieved follow up.

Primary Outcomes

The primary outcomes of the research paper indicate that perturbation training led to a lower incidence of injurious falls compared to usual treatment at the 3-month follow-up. Specifically, 5.7% of the perturbation training group experienced injurious falls, whereas 13.3% of the usual treatment group did. The relative risk of injurious falls at 3 months was 0.43, and in the adjusted model, it was 0.38, both of which were statistically significant. Additionally, a lower proportion of individuals in the perturbation training group who experienced injurious falls sought hospital evaluation and treatment compared to the usual treatment group. The survival analysis showed a separation of the curves in the first 3 months, indicating a lower risk of injurious falls in the perturbation training group. However, there was no significant difference when viewed over the entire first year.

In terms of any falls (injurious and non-injurious), 28.3% of the perturbation training group reported a fall at 3 months compared to 36.7% in the usual treatment group. The relative risk of any fall at 3 months was 0.78, and in the adjusted model, it was 0.83, although these findings were not statistically significant. Furthermore, the zero-inflated negative binomial mixed regression model over 1 year showed that the relative risk of any fall in the perturbation training group was 0.82, which bordered on statistical significance.

Secondary Outcomes

The measurements in balance, mobility, and confidence improved for both perturbation training group and usual treatment group, but no meaningful difference was achieved between groups. No adverse events were identified in either group during the study.

Discussion

The research paper presents findings from a comparative effectiveness trial that evaluated the addition of surface perturbation treadmill training as part of multi-modal physical therapy for preventing falls and fall-related injuries in high-risk older adults. The results showed a significant reduction in fall-related injuries at 3 months but no significant reduction in falls between groups or in fall-related injuries at 1 year. The effect of perturbation training seemed to wear off at 3 months, consistent with other exercise interventions to prevent falls. Prior studies suggested possible retention of perturbation training effects over longer time periods. The results also indicated that a "booster" session of perturbation training after 3 months may help retain improvements in reactive balance control. Furthermore, the reduction in injurious falls in the perturbation training group occurred despite no differences in standard clinical fall risk and balance assessments between groups. The study suggested potential explanations for the reduction in fall-related injuries, including preferential reduction in major versus minor falls or partial recovery after an unexpected perturbation. However, these explanations require additional study in future research. The paper also highlighted that traditional measures of fall risk were similar between treatment groups, suggesting that the addition of perturbation training to the multimodal exercise intervention did not adversely affect these standard measures of program effectiveness. The findings of this study provide valuable insights into the potential benefits and limitations of surface perturbation treadmill training as part of multi-modal physical therapy for preventing fall-related injuries in high-risk older adults.

Implications

The integration of surface perturbation training alongside standard gait and balance training for high-risk older adults has the potential to significantly decrease the risk of fall-related injuries. The study's pragmatic approach, allowing physical therapists flexibility in incorporating the surface perturbation training into patients' treatment, indicates that the findings are likely applicable to current clinical practice. It is uncertain whether a more intensive or standardized perturbation training protocol could result in a greater reduction in injurious falls or a significant overall reduction in falls, but the study's results suggest that further investigation is justified. To determine the most effective protocols for perturbation-based training, future research needs to evaluate factors such as the type, magnitude, direction, frequency, and volume of perturbations as well as their impact on different patient subgroups. Overall, the study implies that integrating surface perturbation training into standard gait and balance training for high-risk older adults could have substantial benefits in reducing the risk of fall-related injuries, with the need for more research to establish optimal training protocols and their efficacy across different patient populations.

Opportunities for Future Research

1. Optimal frequency, dose, and progression: Future research could focus on determining the most effective frequency, dose, and progression of surface perturbation training, considering variables such as the duration and intensity of training sessions, to achieve the best outcomes in reducing fall-related injuries in high-risk older adults.

2. Long-term effectiveness: Further studies are warranted to investigate the long-term effectiveness of surface perturbation training in reducing injurious falls beyond the initial 3-month period studied in the original trial. Exploring the sustainability of the intervention's effects over a longer duration could provide valuable insights.

3. Standardized perturbation training protocols: Future research can explore the development and testing of standardized perturbation training protocols to establish consistent guidelines for the type, magnitude, direction, and volume of perturbation-based training, thereby optimizing the intervention's efficacy in different patient subsets.

4. Effects in different patient subsets: Opportunities exist to investigate the effects of surface perturbation training in different subsets of high-risk older adults, such as those with specific comorbidities or functional limitations, to determine the intervention's impact across diverse patient populations.

5. Integration of perturbation training: Studies could explore the integration of surface perturbation training into various rehabilitation settings and therapy programs, assessing its effectiveness within different clinical contexts and in combination with other interventions for balance and fall prevention.

6. Booster sessions: Research could focus on determining the potential benefits of incorporating "booster" sessions of perturbation training after the initial intervention, aiming to enhance the retention of improvements in reactive balance control over longer periods, which would contribute to the sustainability of the intervention's effects.