Low intensity exercise training in patients with amyotrophic lateral sclerosis - factors influencing eligibility and compliance to the clinical trial.

Background: To date, there are no evidence-based recommendations for physical therapy in amyotrophic lateral sclerosis (ALS). The reason is a low number of related clinical trials (CTs), restricted sample sizes and a high dropout rate. It may influence the profile of the participants, while the final results might not translate to the general ALS population.

Objective: To analyze factors affecting the ALS patients' enrollment and retention to the study, and to describe a profile of participants as compared to the eligible group.

Methods: A total of 104 ALS patients were offered participation in a CT of low-intensity exercises at home. Forty-six patients were recruited. Demographic and clinical data (El Escorial criteria, site of onset, diagnosis delay, disease duration, amyotrophic lateral sclerosis functional rating scale - revised [ALSFRS-R], Medical Research Council [MRC], hand-held dynamometry) were analyzed every 3 months.

Results: Male gender, younger age and a higher ALSFRS predicted enrollment, while male gender, higher ALSFRS-R and MRC predicted retention in the study. A long commute to the study site and a fast disease progression were the main reasons influencing both enrollment and retention. Despite a high dropout rate, study participants were representative for the general ALS population.

Conclusion: The above demographic, clinical and logistic factors need to be considered when designing studies in ALS population.