Background: Elderly patients are a growing population in cardiac rehabilitation (CR). As postural control declines with age, assessment of impaired balance is important in older CR patients in order to predict fall risk and to initiate counteracting steps. Functional balance tests are subjective and lack adequate sensitivity to small differences, and are further subject to ceiling effects. A quantitative approach to measure postural control on a continuous scale is therefore desirable. Force plates are already used for this purpose in other clinical contexts, therefore could be a promising tool also for older CR patients. However, in this population the reliability of the assessment is not fully known.
Research question: Analysis of test-retest reliability of center of pressure (CoP) measures for the assessment of postural control using a force plate in older CR patients.
Methods: 156 CR patients (≥75 years) were enrolled. CoP measures (path length (PL), mean velocity (MV), and 95% confidence ellipse area (95CEA)) were analyzed twice with an interval of two days in between (bipedal narrow stance, eyes open (EO) and closed (EC), three trials for each condition, 30 s per trial), using a force plate. For test-retest reliability estimation absolute differences (Δ: T0-T1), intraclass correlation coefficients (ICC) with 95% confidence intervals, standard error of measurement and minimal detectable change were calculated.
Results: Under EO condition ICC were excellent for PL and MV (0.95) and good for 95CEA (0.88) with Δ of 10.1 cm (PL), 0.3 cm/sec (MV) and 1.5 cm2 (95CEA) respectively. Under EC condition ICC were excellent (≥ 0.95) for all variables with larger Δ (PL: 21.7 cm; MV: 0.7 cm/sec; 95CEA: 2.4 cm2).
Significance: In older CR patients, the assessment of CoP measures using a force plate shows good to excellent test-retest reliability.
Keywords: Cardiac rehabilitation; Force plate; Older patients; Postural control; Test-retest reliability.
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