Performance and Self-reported Functioning of People With Chronic Idiopathic Axonal Polyneuropathy: A 4-Year Follow-up Study

Objective: To describe the course of performance of activities (observed and self-reported) of people with chronic idiopathic axonal polyneuropathy (CIAP) over 4 years and to assess the associations with muscle strength, sensory function, and psychological personal factors (intention, perceived behavior control [PBC], and feelings of depression or anxiety). Design: Prospective observational study with measurement at baseline, 6 months, 1 year, and 4 years. Setting: Outpatient neurology clinic. Participants: People with CIAP (N=92). Main Outcome Measures: Walking was measured using the shuttle-walk test (SWT), a pedometer (mean step count/d), and the “physical functioning” subscale of the Short Form-36 questionnaire. Muscle strength and sensory function were measured using a MicroFET handheld dynamometer and the Sensory Modality Sum score. Personal factors were assessed with the Hospital Anxiety and Depression Scale, and intention and PBC were assessed with a protocolized questionnaire. Results: Multilevel model analysis showed a significant decrease over time in mean scores in performance of activities (SWT, step count), which was associated with older age and loss of muscle strength (SWT: β=73.392, step count: β=676.279, P<.001). Limitations in self-reported functioning (physical functioning) significantly increased and were associated with older age (β=−0.916, P=.001), increased comorbidity (β=−6.978, P=.024), loss of muscle strength (β=7.074, P<.001), low PBC (β=0.744, P<.001), and increased feelings of depression (β=1.481, P<.001). Conclusions: Performance of activities of people with CIAP decreased over time (SWT, step count, physical functioning). Older age, loss of muscle strength, comorbidity, feelings of depression, and low perceived behavior control were associated with this decrease. However, there were considerable individual differences.