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

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 max lag), synchronization at lag zero (ρ 0 ), 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 max lag in the AP and ML directions, as well as ρ 0 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.

Reliability and minimal detectable change of body-weight distribution and body sway between right and left brain-damaged patients at a chronic stage

“…Nonetheless, we found no significant difference between the two populations. Our results confirm those of previous studies on stroke patients in which the side of the brain damaged was not considered [5,20]. As already mentioned, we found excellent reliability of WBA, although the interval between the two sessions was longer than that in the current literature (i.e.…”

“…Given that the parameters of WBA and MLCOP are related [21], such results are not surprising. Although our results confirm those of Martello et al [5], they differ from those of other studies, which found weaker reliability for this parameter, likely due to various reasons, such as the stage of recovery (subacute versus chronic stroke) [4], the platform used (single versus double platform) [2], the longer duration (10s versus 30s) [4], and larger distance between the feet (3cm versus 14cm) [2]. Reliability of the APCOP measurement was also found to be excellent for LBD patients, whereas that of RBD patients was only moderate to poor.…”

“…As already mentioned, we found excellent reliability of WBA, although the interval between the two sessions was longer than that in the current literature (i.e. 2 weeks) [5]. We also found the reliability of the MLCOP measurement to be excellent, with again the exception of the EC condition for LBD patients.…”

“…Body sway (BS), which is defined by an area or velocity of sway, can also be found after a stroke [3]. The reliability of these parameters has been regularly assessed in the literature [2,4,5]. However, the measurements obtained for the various parameter conditions must be carefully taken.…”

“…Evaluation on a double-force platform rather than a single-force platform is recommended for the measurement of WBA and the shift in the MLCOP [6]. Martello et al [5] studied WBA in chronic stroke patients using a double platform and found good reliability but studied only a small population of 16 participants. This result thus requires confirmation on a larger population.…”