Reliability and minimal detectable change of between-limb synchronization, weight-bearing symmetry, and amplitude of postural sway in individuals with stroke

Martello, Suzane Ketlyn; Boumer, Tatiane Caroline; Almeida, Juliana Carla de; Correa, Katren Pedroso; Devetak, Gisele Francine; Faucz, Rodrigo; Manffra, Elisangela Ferretti

doi:10.1590/2446-4740.06816

Acessibilidade / Reportar erro

Brasil

Research on Biomedical Engineering

Español English

Brasil

Español English

sumário « anterior atual seguinte »

Sumário

Original Articles • Res. Biomed. Eng. 33 (2) • Apr-Jun 2017 • https://doi.org/10.1590/2446-4740.06816 copy

Reliability and minimal detectable change of between-limb synchronization, weight-bearing symmetry, and amplitude of postural sway in individuals with stroke

Authorship SCIMAGO INSTITUTIONS RANKINGS

Abstract

Introduction:

Recently, variables related to between-limb synchronization of the centers of pressure (COP) have been proposed as measures of postural control in post-stroke patients. Although it is crucial in verifying their potential clinical use, the reliability of these variables is unknown. The aim of this work was to determine the reliability and minimal detectable change (MDC) of the peak of synchronization (ρ_max) in the anteroposterior (AP) and mediolateral (ML) directions, the time lag for the peak (ρ_maxlag), synchronization at lag zero (ρ₀), weight-bearing symmetry, and amplitude of postural sway, measured as the root mean square (RMS) values of the COP displacements in both directions (AP and ML COP displacement).

Methods

COP data of 16 participants with stroke were collected at quiet standing with two force plates at two sessions separated by 2 to 7 days. The procedure was repeated three times in each session. The within and between sessions reliability was determined by the intraclass correlation coefficient (ICC), and the MDC was obtained from the ICC between sessions.

Results

The variables ρ_maxlag in the AP and ML directions, as well as ρ₀ in the AP direction, exhibited poor within session reliability (ICC ≤ 0.4). The findings revealed excellent within and between sessions reliability (ICC ≥ 0.89) for weight-bearing symmetry and the RMS displacement in the AP direction, with MDC values of 5% and 2.07 mm, respectively. The remaining variables exhibited moderate reliability.

Conclusion

Weight-bearing symmetry and AP COP displacement can be considered reliable variables for use in clinical practice.

Keywords:
Reliability; Minimal detectable change; Synchronization; Center of pressure; Stroke; Posturography

Variable	Median
Variable	(min-max)
Age (yr).	55 (33-78)
Time post-stroke (mo.).	6.5 (1-20)
Weight (kg).	67.8 (57.9-88.8)
Height (m).	1.63 (1.50-1.77)
Body mass index (kg/m²).	25.6 (21.3-32.7)
Functional ambulation category (FAC).	4 (3-5)
Barthel index.	83 (65-100)
Berg balance scale.	38 (19-56)
Spasticity of the plantar flexors of the paretic limb.	2 (0-4)
Ankle proprioception of the non-paretic limb (normal / impaired / absent).	14 / 0 / 2
Ankle proprioception of the paretic limb (normal / impaired / absent).	14 / 1 / 1
Stroke etiology (hemorrhagic/ischemic).	4/12
Hemiparetic side (left / right).	5/11

Test/ Retest	Variable	Median (minimum-maximum)
Test/ Retest	Variable	R1	R2	R3	Average of Repetitions
TEST	AP ρ_max	0.77 (–0.42-0.85)	0.67 (–0.18-0.88)	0.64 (–0.40-0.92)	0.65 (–0.03-0.85)
	AP ρ_maxlag (s)	0.00 (–0.48-1.00)	0.00 (–0.25-1.00)	0.00 (–0.18-0.50)	0.00 (–0.18-0.49)
	ML ρ_max	–0.43 (–0.92-0.36)	–0.53 (–0.87-0.25)	–0.58 (–0.90-0.46)	–0.43 (–0.81-0.35)
	ML ρ_maxlag (s)	0.01 (–1.00-1.00)	0.00 (–1.00-1.00)	0.01 (–0.42-1.00)	0.02 (–0.31-1.00)
	AP ρ₀	0.74 (0.00-0.85)	0.67 (0.15-0.88)	0.64 (–0.05-0.92)	0.65 (0.17-0.85)
	ML ρ₀	–0.43 (–0.91-0.24)	–0.53 (-0.87-0.46)	–0.58 (–0.87-0.24)	–0.49 (–0.81-0.19)
	Symmetry (%)	32.16 (14.27-9.57)	33.64 (15.10-49.41)	33.87 (13.39-49.43)	33.10 (14.25-48.97)
	AP COP displacement (mm)	7.50 (1.89-21.46)	7.26 (2.74-18.34)	7.46 (2.20-21.14)	7.30 (2.28-20.32)
	ML COP displacement (mm)	10.88 (4.20-39.88)	10.05 (4.32-35.40)	11.15 (4.06-25.50)	10.86 (5.47-32.34)
RETEST	AP ρ_max	0.55 (-0.48-0.87)	0.58 (–0.27-0.90)	0.54 (–0.31-0.89)	0.51 (–0.05-0.78)
	AP ρ_maxlag (s)	–0.01 (-0.23-1.00)	–0.01 (–1.00-1.00)	–0.02 (–1.00-0.03)	–0.01 (–0.46-0.35)
	ML ρ_max	–0.34 (-0.77-0.35)	–0.49 (–0.88-0.45)	–0.34 (–0.74-0.46)	–0.29 (–0.77-0.25)
	ML ρ_maxlag (s)	0.00 (-1.00-0.94)	–0.01 (–1.00-0.16)	0.01 (–1.00-1.00)	–0.04 (–0.66-0.52)
	AP ρ₀	0.55 (-0.31-0.86)	0.57 (–0.02-0.90)	0.52 (0.15-0.89)	0.51 (0.15-0.78)
	ML ρ₀	–0.34 (-0.76-0.19)	–0.47 (–0.87-0.14)	–0.40 (–0.74-0.34)	–0.35 (–0.77-0.17)
	Symmetry (%)	38.35 (21.15-49.25)	37.04 (18.02-49.89)	37.34 (20.50-48.92)	38.10 (20.62-49.35)
	AP COP displacement (mm)	6.74 (3.05-16.51)	6.54 (4.12-18.41)	6.90 (3.96-16.67)	7.40 (3.87-17.20)
	ML COP displacement (mm)	13.41 (4.85-27.49)	11.70 (6.10-28.87)	8.01 (4.97-28.48)	11.24 (6.35-28.28)

Variable	Test		Retest
Variable	ICC within session	95% CI	ICC within session	95% CI
AP ρ_max	0.57	0.27-0.80	0.18	–0.11-0.53
AP ρ_maxlag	–0.06^* * Negative values due to a negative average correlation among items.	–0.27-0.28	–0.013^* * Negative values due to a negative average correlation among items.	–0.22-0.32
ML ρ_max	0.57	0.28-0.80	0.20	–0.09-0.55
ML ρ_maxlag	0.16	–0.12-0.52	0.08	–0.16-0.43
AP ρ₀	0.32	0.02-0.64	0.13	–0.14-0.49
ML ρ₀	0.59	0.30-0.81	0.37	0.06-0.67
Symmetry	0.96	0.92-0.99	0.95	0.88-0.98
AP COP displacement	0.89	0.77-0.96	0.88	0.76-0.95
ML COP displacement	0.72	0.47-0.88	0.60	0.31-0.82

Variable	ICC between sessions	95% CI	SEM	MDC
AP ρ_max	0.73	0.22-0.90	0.15	0.47
AP ρ_maxlag	0.72	0.19-0.90	0.72	2.16 s
ML ρ_max	0.55	–0.30-0.84	0.23	0.69
ML ρ_maxlag	0.78	0.36-0.92	1.17	3.52 s
AP ρ₀	0.88	0.67-0.96	0.07	0.21
ML ρ₀	0.70	0.14-0.90	0.16	0.47
Symmetry	0.97	0.91-0.99	1.66	5.00%
AP COP displacement	0.97	0.92-0.99	0.69	2.07 mm
ML COP displacement	0.94	0.82-0.98	1.60	4.81 mm

Sociedade Brasileira de Engenharia Biomédica Centro de Tecnologia, bloco H, sala 327 - Cidade Universitária, 21941-914 Rio de Janeiro RJ Brasil, Tel./Fax: (55 21)2562-8591 - Rio de Janeiro - RJ - Brazil
E-mail: rbe@rbejournal.org

Acompanhe os números deste periódico no seu leitor de RSS

[1] *Corresponding author: Health Technology Graduation Program, Pontifícia Universidade Católica do Paraná – PUCPR, Imaculada Conceição, 1155, CEP 80215-901, Curitiba, PR, Brazil. E-mail: susiketlyn@hotmail.com