72 Test-Retest Reliability and Minimal Detectable Change for Postural Sway by using Sway Meter in Elderly Subjects

Abstract Introduction Static postural stability is the ability to maintain the posture with minimum sway. Increasing postural sway during standing in different sensory conditions is associated with aging due to decline in sensory and motor functions. Sway area measured by using sway meter is usually simple method for assessing postural stability in elderly subjects. Like many biological measurements, sway area has an intrinsic variability that affects their test-retest reliability and responsiveness of postural stability assessment. The minimal detectable change (MDC) is ability to detect smallest change beyond measurement error that reflects a reliable change. Therefore, the MDC value could provide information of clinical relevance on postural stability. The aims of this study were to determine test-retest reliability and MDC of sway area obtained from sway meter in elderly subjects. Methods Twelve healthy elderly subjects aged 60 years and above were participated in this study. The test and retest repeatability of postural sway measurements were performed twice with a 1-hour interval. For each subject was assess postural sway using Lord’s sway meter during standing on 4 sensory conditions for 30 seconds of each condition. The test-retest reliability of sway area was calculated using intraclass correlation coefficient. The MDC for each sway area was calculated to quantify clinical relevance. Results The test-retest reliability of sway area revealed good to excellent reliability ranged from 0.85 to 0.94. Standard error of measurement (SEM) and MDC ranged from 75 to 205 mm2 and 209 to 568 mm2, respectively. Discussion and Conclusion Our findings reveal that sway area in different sensory conditions could be used in assessment of postural stability in elderly subjects. SEM and MDC of sway area increased when subjects were asked to close their eyes and on foam surface. The sway meter is a reliable tool for assessing postural stability in clinical setting.