Myotonic Dystrophy type 1 (DM1) is one of the most heterogeneous hereditary disease in terms of age of onset, clinical manifestations, and severity, challenging both medical management and clinical trials. The CTG expansion size is the main factor determining the age of onset although no factor can finely predict phenotype and prognosis. Differences between males and females have not been specifically reported. Our aim is to study gender impact on DM1 phenotype and severity. We first performed cross-sectional analysis of main multiorgan clinical parameters in 1409 adult DM1 patients (>18y) from the DM-Scope nationwide registry and observed different patterns in males and females. Then, we assessed gender impact on social and economic domains using the AFM-Téléthon DM1 survey (n = 970), and morbidity and mortality using the French National Health Service Database (n = 3301). Men more frequently had (1) severe muscular disability with marked myotonia, muscle weakness, cardiac, and respiratory involvement; (2) developmental abnormalities with facial dysmorphism and cognitive impairment inferred from low educational levels and work in specialized environments; and (3) lonely life. Alternatively, women more frequently had cataracts, dysphagia, digestive tract dysfunction, incontinence, thyroid disorder and obesity. Most differences were out of proportion to those observed in the general population. Compared to women, males were more affected in their social and economic life. In addition, they were more frequently hospitalized for cardiac problems, and had a higher mortality rate. Gender is a previously unrecognized factor influencing DM1 clinical profile and severity of the disease, with worse socio-economic consequences of the disease and higher morbidity and mortality in males. Gender should be considered in the design of both stratified medical management and clinical trials.

Patients-Reported Outcomes (PRO) are increasingly used in clinical and epidemiological research. Two main types of analytical strategies can be found for these data: classical test theory (CTT) based on the observed scores and models coming from Item Response Theory (IRT). However, whether IRT or CTT would be the most appropriate method to analyse PRO data remains unknown. The statistical properties of CTT and IRT, regarding power and corresponding effect sizes, were compared.

To assess the burden on family carers of persons with muscular dystrophy living in their homes and to determine factors contributing to carer burden. The study included 56 dyads of people with muscular dystrophy and their family carers. The variables for carer burden were compared by logistic regression in 2 carer groups (burden + /burden-). The mean age of the patients with muscular dystrophy was 32.7 years (median 26.7, range 15-65 years) and that of the carers 51 years (median 48, range 30-80 years). The carers reported the care burden using the Zarit Burden Inventory (median score 23, range 0-57/88). Multivariate analysis produced 3 adjusted explicative factors: carer characteristics related to risk of perceived burden are self-report of poor social functioning on the SF-36 (OR = 26.6 (2.6-278); p=0.006), self report of anxiety on the Hospital Anxiety Scale (OR = 7.1 (1.4-36); p=0.02) and being a carer under 48 years of age (OR = 7.8 (1.7-34.5); p=0.007). However, it was difficult to dissociate the different health variables of the carers from each other. This approach should lead to better decision-making by medical teams, patients and their carers.