Test-Retest Reliability of Dynamic Balance Performance-Based Measures Among Adults With a Unilateral Lower-Limb Amputation.

BACKGROUND: There is large variation in administration of performance-based, dynamic balance measures among adults with lower-limb amputation (LLA). Further, there has been limited exploration of test-retest reliability of these measures in adults with lower-limb loss, including whether there is a difference in reliability if one records "best" versus "average" performance across trials.

OBJECTIVE: To determine test-retest reliability of several balance tests for both "best" and "average" score performance in community-dwelling adults with a unilateral LLA, including quantification of the precision of individual scores (standard error of the measurement, SEM) and estimates of minimal detectable change (MDC90 ).

DESIGN: Cross-sectional study.

SETTING: Mobile research laboratory.

PARTICIPANTS: 27 participants (55.5% female) with an average age of 51 (SD = 12.2) years, who were predominantly community-ambulators (92.5%), after a unilateral transtibial (n = 20), transfemoral (n = 5), or other major lower-extremity (n = 2) amputation, were included. Median time since amputation was 6.3 (2.3, 19) years.

METHODS: Reliability was evaluated using intraclass correlation coefficient (ICC) models (3,1 or 3,k). SEMs and MDC90 values with 95% confidence intervals (CIs) were calculated.

MAIN OUTCOME MEASURES: 360o Turn Test, 5 Times Sit-To-Stand, Functional Reach Test, Figure-of-8 Walk Test, and Four Square Step Test (FSST).

RESULTS: The ICCs (3,1 or 3,k) for all tests (for both "best" and "average" performance) were considered good-to-excellent and CIs varied from 0.69 (95% CI = 0.40-0.85) to 0.97 (95% CI = 0.95-0.99). For most tests, "best" and "average" performance demonstrated similar ICC values. MDC90 values did not surpass 10% of test means for any of the measures.

CONCLUSIONS: The dynamic balance measures evaluated for use among community-dwelling adults with a unilateral LLA demonstrated excellent reliability, along with high precision of scores and MDC values that did not exceed 10% of testing means. Either best or average scoring may be used when administering the majority of these tests, as long as the assessment method is appropriately documented and replicated at follow-up to allow direct comparisons. With the FSST, clinicians should consider taking the average of two FSST trials.

LEVEL OF EVIDENCE: III.