Modelling the epidemiology of Duchenne muscular dystrophy provides insights into the overall population and selected subpopulations in nine countries

Duchenne muscular dystrophy (DMD) is a rare X-linked neuromuscular disease caused by mutations in the DMD gene, leading to progressive muscle weakness, diminished quality of life and premature death. We aimed to develop an epidemiology model for DMD, providing country-specific prevalence estimates of the total diagnosed population and selected subpopulations. To estimate DMD prevalence, country-specific inputs were derived from population statistics and a literature review of epidemiological data. Diagnosed incidences, considering historic trends, were applied to the number of effective live male births each year from 1950 onwards. Newly diagnosed patients entered the model based on the distribution of the age of diagnosis and patients left the model based on birth cohort-dependent survival. The estimated total number of individuals with DMD was calculated for each calendar year as the sum of patients from previous years who had not left the model owing to death and newly diagnosed patients. To assess validity, estimated DMD prevalence was compared with published prevalence. For the year 2023, the estimated total number of individuals with DMD was 5249 in Brazil, 1003 in Canada, 27 931 in China, 2082 in France, 2071 in Germany, 1361 in Italy, 3110 in Japan, 1169 in Spain and 2055 in the UK. Age group distribution was comparable across countries, with an approximately equal representation of paediatric and adult populations. Projections of total number of patients with DMD for each country from the year 2023 to 2040 showed variable trends. In European countries, 65% of patients with DMD were estimated to be non-ambulatory. The model-estimated prevalence showed good alignment with published prevalence. These findings provide robust prevalence estimates that increase our understanding of the epidemiology of DMD.