Life expectancy is improving among individuals with Duchenne muscular dystrophy (DMD), according to a meta-analysis published in Neurology.
Study results showed that patients with DMD born following 1990 had an increased median life expectancy of 28.1 years, compared with a combined cohort median life expectancy of 22.0 years.
The study provides comprehensive survival probabilities and all-cause mortality rates for different age groups across the DMD lifespan. The researchers calculated the maximum age of survival to be 44.4 years old. Probabilities of survival for individuals with DMD at 10, 20, 30, and 40 years of age were 99.8%, 59.5%, 26.1%, and 13.3%, respectively.
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“This work highlights improvements in survival for patients with DMD over time, as standards of care have increased,” the authors said. “We strongly advocate the need to include mortality data in any natural history model, in order to accurately represent the whole natural history.”
The investigators performed a systematic review of the literature and identified 1177 articles of which 14 met the inclusion criteria for this meta-analysis. These 14 articles contained data on 2283 patients, of whom 1049 were deceased.
Next, the researchers reconstructed the individual patient data in a digitized format using Kaplan-Meier (KM) survival curves with patient age as a timescale.
The investigators analyzed the data first as a combined cohort. Then, they performed a secondary analysis following the stratification of the patient data into 3 birth cohorts: pre-1970, 1970-1990, and post-1990. This allowed for the analysis of trends in life expectancy over time, particularly after steroid treatments became the mainstay of DMD treatment after the 1990s.
The median survival ages for the pre-1970, 1970-1990, and post-1990 birth cohorts were 18.3, 24.0, and 28.1 years, respectively.
Limitations primarily involved restricted access to both identified studies and to individual patient data within specific studies. The lack of access to the full individual patient data in the studies caused problems with assigning patients to birth cohorts as well as forced consequent assumptions that all patients in the studies were followed up since birth. This assumption introduced the possibility of immortal time bias into the study, which may have impacted the end results.
Broomfield J, Hill M, Guglieri M, Crowther M, Abrams K. Life expectancy in Duchenne muscular dystrophy: reproduced individual patient data meta-analysis. Neurology. Published online October 13, 2021. doi:10.1212/WNL.0000000000012910