Activity limitations in patients with neuromuscular disorders: a responsiveness study of the ACTIVLIM questionnaire

Recently, a self-reported scale of activity limitations, the ACTIVLIM questionnaire, was developed and validated in patients with neuromuscular disorders (NMD). The purpose of this study was to investigate its sensitivity to change. One hundred thirty-two patients with NMD (mean age, range: 31, 6-80) were assessed twice, with 21+/-4 months in between, using the ACTIVLIM questionnaire. Mean score change, effect size, standardized response, mean paired t-test and an individual-level statistical approach were calculated for groups of patients according to their self-rated functional status evolution and for three main diagnostic groups (Ambulant and wheelchair-bound Duchenne muscular dystrophy patients, myotonic dystrophy patients, and patients with Charcot-Marie-Tooth neuropathy). The responsiveness indices showed that the change in activity measures was higher in patients who reported deteriorated functional status and in patients with Duchenne muscular dystrophy. The ACTIVLIM questionnaire showed a good sensitivity to change and could be useful in research settings to characterize the disease course of NMD.