Dynamic sitting balance control tests in stroke survivors: a study of reliability and validity

Abstract

BACKGROUND: Stroke survivors may have difficulties to maintain sitting balance due to the impaired control of trunk muscles. However, the temporal and spatial domains of dynamic sitting balance test for stroke survivors are lacking. AIMS: To investigate the reliability and validity of two sitting balance tests, namely limits of stability test (LOS) and sequential weight shifting test (SWS) in stroke survivors. METHODS: Eleven community-dwelling stroke survivors with onset for at least two years (mean time since stroke = 8.0 years [SD 4.0]) and 15 healthy subjects were recruited. Reaction time, maximum excursion, directional control of LOS, and total movement time and directional control of SWS were measured. Modified Function Reach Test (MFRT) and Trunk Impairment Scale (TIS) were also conducted to correlate with LOS and SWS. RESULTS: Excellent test-retest reliability was demonstrated in reaction time (ICC[3,8] = 0.760) and maximum excursion (ICC[3,8] = 0.929) of LOS and total movement time of SWS (ICC[3,3] = 0.864) in stroke survivors. Known groups validity was only shown in reaction time of LOS (p = 0.039) between the two groups. Reaction time of LOS of stroke subjects was significantly correlated with MFRT (r = –0.684, p = 0.020), while directional control of LOS was significantly correlated with the dynamic sitting balance score (r = 0.846, p = 0.001) and total score (r = 0.817, p = 0.002) of TIS. For SWS, total movement time was significantly correlated with dynamic sitting balance score of TIS (r = –0.654, p = 0.029). CONCLUSION: Moderate to excellent test-retest reliability was found in LOS and SWS tests in stroke survivors. The convergence and discrimination perspectives of construct validity were established.