Development of a clinical Multiple-Lunge test to predict falls in older adults
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Background: The incidence of falls and severity of fall related injuries steadily increase with age. As well as physical injury, falls can lead to adverse psychological and social consequences, which can further reduce older adults’ quality of life. The most commonly reported cause of falls in older persons is tripping over an obstacle, which may reflect the difficulty many older adults have in making an appropriate stepping response. In order to reduce the number of falls experienced by older adults, individuals at high risk of falling need to be identified so that targeted interventions can be implemented. Aims: This series of studies aimed to develop a new Multiple-Lunge test to distinguish between Fallers and Non-fallers in independent older adults, aged 65 years and over. The studies sought to determine the test-retest reliability of the Multiple-Lunge test; as well its validity to predict faller status in a sample of community-dwelling older adults. Methods: One hundred and thirty community-dwelling older adults, aged 65 – 93 years (mean age 77 ± 7 years) with (n = 40) and without (n = 90) a history of falls were administered the Multiple-Lunge test. For the purpose of this study, a Faller was classified as an older adult with a history of one fall, or a Multiple-faller if there was a history of two or more falls in the previous 12 months. The Multiple-Lunge test required the individual to lunge forward to a step length determined as 60% of their leg length, and return to start position, for a total of five repetitions. Two trials were performed after a familiarisation trial. The number of correct steps and the total time for the five steps were recorded for each trial. The highest number of correct steps and the lowest total time of the two trials were used for data analysis. Test-retest reliability of the Multiple-Lunge test was established across two testing occasions from a sub-sample of the validity study (n = 14, mean age 79 ± 6 years). A cross-sectional design was used to establish the sensitivity and specificity of the Multiple-Lunge test to predict faller status based on retrospective self-reported fall history. Initial analysis using the number of correct steps and total time, was followed by a linear regression analysis to determine the validity of the test to predict falls. Results: The Multiple-Lunge test was found to be reliable across trials (ICC = 0.79 for number of correct steps; ICC = 0.86 for total time). The change in the mean for steps was small and similar across four trials (-0.43 steps, -0.36 steps, -0.50 steps). The change in the mean for time showed a gradual decrease in time scores across trials (-0.69 seconds, -0.73 seconds, -0.93 seconds). Sensitivity and specificity values were calculated as 73% and 63% for predicting Multiple-fallers using the measure of all five steps done correctly. Linear regression analysis did not indicate that the Multiple-Lunge test could be used to predict faller status for either of the step predictor variables (0/5 steps or 5/5 steps). However, a very high sensitivity value (98%) was observed for the variable of both steps and time in predicting Fallers. Also a very high specificity value (99%) was recorded for the variable of time to predict Multiple-fallers. Conclusions: The Multiple-Lunge test is an easily administered test for independent older adults. Due to the challenging nature of the test it may be well suited to detect subtle differences in abilities of higher functioning older adults. The test mimics the movements needed in response to a trip, the most common cause of falls in older adults. This test is a reliable and reasonably valid measure of falls risk. A practitioner can be confident in 7 out of 10 cases that an older adult who cannot complete all five steps of the Multiple-Lunge test is at high risk of falls. The results of this thesis suggest that there is potential for the Multiple-Lunge test to be used in clinical practice and fall prevention research. However, additional research on how to further increase its validity and/or to determine the most appropriate populations with which to administer this test appears warranted.