Utility and Results from a Patient-Reported Online Survey in Myotonic Dystrophies Types 1 and 2

Myotonic dystrophies (DMs) are the most frequent autosomal dominant neuromuscular disorders in adults. Our objective was to evaluate the utility of an online survey in a rare disease as well as to assess and compare the onset and the progression of clinical symptoms in patients with myotonic dystrophy types 1 (DM1) and 2 (DM2).

We conducted a patient's reported online survey assessing demographics, disease-related symptoms (age of onset, first symptom, time of diagnosis, current symptoms, inheritance, and family history) combined with capturing current symptoms by validated questionnaires. The questionnaire consisted of open, closed, single- and multiple-choice questions. Multiple answers were possible in some cases. Patients with genetically confirmed DM1 or DM2 who were registered in the German DM registry or the Deutsche Gesellschaft für Muskelkranke e.V. - Diagnostic Group for DMs were invited to participate in this online survey. We calculated descriptive and exploratory analysis, where applicable.

Out of 677 data sets from respondents, 394 were suitable for final analysis, containing completed questionnaires from 207 DM1 (56% female) and 187 DM2 patients (71% female). The median age of onset was 28 years for DM1 and 35 years for DM2. Muscular symptoms were most frequently reported as the first symptom. The onset of myotonia was earlier than the onset of muscle weakness in both DM1 and DM2. Forty-four percent of patients with DM1 and one-third of patients with DM2 indicated muscle weakness as the first symptom. Patients with DM1 were significantly younger when experiencing muscle weakness as first symptom. Fatigue was only mentioned by a small fraction of patients as a first symptom but increased significantly in the course of the disease. There was no statistically significant difference in the incidence of cataracts, cardiac symptoms, and gastrointestinal symptoms between DM1 and DM2. Falls were reported almost equally in both groups, and most of the patients reported 2-3 falls within the past year.

Overall, as our results are consistent with the results of clinical studies and online registries, it can be assumed that this type of systematic gathering of data from patients with rare diseases is useful and provides realistic and appropriate results. Due to the nature of online surveys and the absence of an assessor, some uncertainty remains. Furthermore, survey frauds cannot be completely excluded. An additional clinical assessment could confirm the given information and will improve the utility and validity of reported symptoms participants provide in online surveys. Therefore, we recommend a combination of data collecting by online surveys and clinical assessments.