Minimal and robust clinically important difference of three fatigue measures in chronic stroke survivors

BACKGROUND

Fatigue assessment scale (FAS), fatigue subscale of the Profile of Mood States (POMS-F), and vitality subscale of the Short Form Health Survey (SF-36-VT) are among the first and most widely used adapted tools for assessing post-stroke fatigue.

OBJECTIVE

To identify the minimal clinically important difference (MCID) and robust clinically important difference (RCID) of FAS, POMS-F, and SF-36-VT in stroke survivors.

METHODS

Participants completed the FAS, POMS-F, and SF-36-VT before and after receiving 6-week intervention including graded activity training and pacing therapy. MCID was calculated using the distribution-based and anchor-based methods. Further, accuracy, sensitivity, and specificity of calculated values using the distribution-based method were used for determining RCID.

RESULT

A total of 124 stroke survivors participated in this study. MCID for FAS, POMS-F, and SF-36-VT was found to be 4.86, 3.32, and -10.10 (using score change) and 3.5, 2.5, and -10.5 (using ROC analysis), respectively. Using the distribution-based method, the MCID value obtained for the FAS was in the range of 3.16 to 8.76, for the POMS-F was in the range of 1.49 to 5.63, and for the SF-36-VT was in the range of -15.43 to -5.58. ½SD for FAS, ½ SD and 1.96 SEM for POMS-F, and 1.96 SEM and SD for SF-36-VT showed the best discriminative ability to use as the RCID.

CONCLUSIONS

The MCID and RCID were calculated for FAS, POMS-F, and SF-36-VT using different methods. The results can be used by researchers and clinicians for interpreting their findings in subjects similar to those who participated in this study.

The effects of fatiguing exercise and load carriage on the perception and initiation of movement

Perceptual-motor coordination relies on the accurate coupling of the perceptual and movement systems. However, individuals must also be able to recalibrate to perturbations to perceptual and movement capabilities. We examined the effects of fatigue and load carriage on perceptual-motor coordination for a maximal leaping task. 23 participants completed an incremental fatigue protocol (light to fatiguing intensity stages) on two separate occasions (loaded/unloaded). At baseline and the end of every stage of the protocol, participants made perceptual judgments for the affordance of leaping. The accuracy of responses and reaction times were calculated and mean differences were assessed across exercise intensity and load carriage conditions. No interaction of exercise intensity and load carriage was detected, or main effect of load carriage. A main, quadratic effect of exercise intensity was detected on reaction times, with times decreasing through the moderate stage and increasing through post-fatigue. No effect of exercise/fatigue was detected on perceptual accuracy. The results indicate that exercise at high intensities through fatigue has a significant effect on perceptual-motor calibration. Contrastingly, in response to an action-scaled task, individuals can adequately recalibrate to increased load carriage.