Determining Risk of Falls in Community Dwelling Older Adults: A Systematic Review and Meta-analysis Using Posttest Probability

Abstract

Background: Falls and their consequences are significant concerns for older adults, caregivers, and health care providers. Identification of fall risk is crucial for appropriate referral to preventive interventions. Falls are multifactorial; no single measure is an accurate diagnostic tool. There is limited information on which history question, self-report measure, or performance-based measure, or combination of measures, best predicts future falls.

Purpose: First, to evaluate the predictive ability of history questions, self-report measures, and performance-based measures for assessing fall risk of community-dwelling older adults by calculating and comparing posttest probability (PoTP) values for individual test/measures. Second, to evaluate usefulness of cumulative PoTP for measures in combination.

Data sources: To be included, a study must have used fall status as an outcome or classification variable, have a sample size of at least 30 ambulatory community-living older adults (≥65 years), and track falls occurrence for a minimum of 6 months. Studies in acute or long-term care settings, as well as those including participants with significant cognitive or neuromuscular conditions related to increased fall risk, were excluded. Searches of Medline/PubMED and Cumulative Index of Nursing and Allied Health (CINAHL) from January 1990 through September 2013 identified 2294 abstracts concerned with fall risk assessment in community-dwelling older adults.

Study selection: Because the number of prospective studies of fall risk assessment was limited, retrospective studies that classified participants (faller/nonfallers) were also included. Ninety-five full-text articles met inclusion criteria; 59 contained necessary data for calculation of PoTP. The Quality Assessment Tool for Diagnostic Accuracy Studies (QUADAS) was used to assess each study's methodological quality.

Data extraction: Study design and QUADAS score determined the level of evidence. Data for calculation of sensitivity (Sn), specificity (Sp), likelihood ratios (LR), and PoTP values were available for 21 of 46 measures used as search terms. An additional 73 history questions, self-report measures, and performance-based measures were used in included articles; PoTP values could be calculated for 35.

Data synthesis: Evidence tables including PoTP values were constructed for 15 history questions, 15 self-report measures, and 26 performance-based measures. Recommendations for clinical practice were based on consensus.

Limitations: Variations in study quality, procedures, and statistical analyses challenged data extraction, interpretation, and synthesis. There was insufficient data for calculation of PoTP values for 63 of 119 tests.

Conclusions: No single test/measure demonstrated strong PoTP values. Five history questions, 2 self-report measures, and 5 performance-based measures may have clinical usefulness in assessing risk of falling on the basis of cumulative PoTP. Berg Balance Scale score (≤50 points), Timed Up and Go times (≥12 seconds), and 5 times sit-to-stand times (≥12) seconds are currently the most evidence-supported functional measures to determine individual risk of future falls. Shortfalls identified during review will direct researchers to address knowledge gaps.

Figure 1.

Usefulness of a 2 × 2 table for interpreting test results. In this systematic review and meta-analysis, data about each test from multiple studies were combined to calculate an overall sensitivity and specificity values, and positive (+ LR) and negative (− LR) likelihood ratios. On the basis of consistent epidemiological evidence, pretest probability for future falls was set at 30%. Calculation of pretest odds from pretest probability, followed by calculation of posttest odds, allows estimation of posttest probability. Assuming a moderate effect + LR of 5 and − LR of 0.5, posttest probability after a positive test would increase from 30% to 68%. Assuming a moderate effect − LR of 0.5, posttest probability after a negative test would decrease from 30% to 18%. When test results are positive, the size of the increase in posttest probability beyond pretest predictive toward 100% determines how much “more sure” the clinician can be that an older adult would likely experience a future fall. When test results are negative, how much posttest probability decreases toward 0 from pretest value determines how much “more sure” that an older individual would not be likely to fall.

Figure 2.

PRISMA diagram for the systematic review process. A total of 2294 abstracts were reviewed; these included 500 duplicates and 1430 that did not immediately meet inclusion criteria. A total of 364 full-text articles were retrieved, examined, and appraised: an additional 269 did not meet inclusion criteria. Data were extracted from the remaining 95 articles; 57 of these contained information necessary for calculation of posttest probability.