Longitudinal Outcomes Among Patients With Duchenne Muscular Dystrophy: A Canadian Retrospective Population-Based Study.

AIMS: There are few long-term studies evaluating clinical outcomes and mortality among individuals with Duchenne muscular dystrophy (DMD); particularly using longitudinal health administrative claims data, reflecting populations managed in typical clinical practice. This study aimed to characterize DMD outcomes via a population-based database.

METHODS

Patients with DMD, diagnosed between 01/1979 and 03/2020 at ≤ 10 years of age, were identified using the Manitoba Population Research Data Repository housed at the Manitoba Centre for Health Policy. De-identified longitudinal administrative data from 1998 to 2020 were used to retrospectively assess frequencies and age at first observation of key DMD outcomes including scoliosis, cardiovascular-related complications, severe respiratory-related morbidities, and mortality. Survival analyses using Kaplan-Meier curves were used to describe attrition and estimate probability of patients remaining observation-free by age.

RESULTS

This study included 198 patients with median (IQR) follow-up of 9.6 (6.6-15.5) years. Corticosteroid use was observed in 26%, with a mean (SD) percentage of days covered of 31% (39%) from initiation to end of follow-up. Scoliosis observations were captured in 18% (median[IQR] age 12 [11-15] years at first observation), severe respiratory-related morbidities in 20% (14[6.5-18] years), and cardiovascular-related complications in 32% of the cohort (12.5[2-20.5] years). Mortality was observed in 14% of the cohort. Kaplan-Meier curves estimated 15% mortality by age 20 years and 20% by 25 years.

DISCUSSION: In a population-based data set with decades of follow-up, these data provide longitudinal observations of the substantial burden of DMD, and insight into contemporary estimates of mortality and treatment patterns in Canada.