Life Expectancy Increasing for DMD Patients, 40-year Analysis Finds
Life expectancy has been increasing in patients with Duchenne muscular dystrophy (DMD), according to an analysis of some 40 years of data, spanning births from before 1970 to the late 2000s.
In fact, the median life expectancy of males with DMD born in the late 1990s advanced to more than 28 years.
“This work highlights improvements in survival for patients with DMD over time, as standards of care have increased,” the investigators wrote.
The study, “Life Expectancy in Duchenne Muscular Dystrophy: Reproduced Individual Patient Data Meta-analysis,” was published in the journal Neurology.
Knowing the natural progression of DMD is important for estimations of cost-effectiveness when developing new treatments. Life expectancy of people with DMD has been reported to be increasing, but estimating survival in this patient population still needs appropriate assessments across the whole disease pathway.
Additionally, assessing life expectancy among those with DMD may be important for disease management, as well as for counseling patients and caregivers.
To address the knowledge gap here, scientists in the U.K. and Sweden conducted a meta-analysis — a type of study in which researchers pool data from multiple published studies and analyze them collectively. Due to their varied study data, meta-analyses have more power to find meaningful conclusions than do individual studies.
The team focused on 14 papers that provided information on 2,283 patients with DMD. A total of 1,050 had died.
These studies were conducted worldwide, in the U.S., Europe, Chile, and Japan. They covered a range of events from birth, to clinic admittance, and death, with the earliest patients born in 1954 and the latest in the late 2000s.
The results showed that the maximum survival age was 44.4 years, and the median survival age across the whole group was 22.
Survival probabilities decreased with age. It was 99.8% at age 10, 59.5% at age 20, 26.1% at age 30, and 13.3% at age 40.
Further analysis suggested an improvement in life expectancy over time. Among patients born before 1970, the median survival age was 18.3 years. But analysis of the period from 1970 to 1990 showed an improvement to 24 years, and assessing the post-1990 period resulted in a further increase to 28.1 years.
The researchers then estimated that for every 1,000 patients ages 20 to 25, a total of 86 would die each year, increasing to 336 each year for those older than 40. Mortality rates were much higher in the group born before 1970 relative to patients born later — 265 of every 1,000 patients aged 25 to 30 who were born before 1970 died every year, compared with 27.6 a year for every 1,000 born after 1990.
“Our work has provided a set of accessible age-specific all-cause mortality rates that can be incorporated into the natural history modelling of DMD,” the scientists wrote.
“This is particularly important for economic decision modelling evaluating future health technologies/treatments, not just in DMD but also as a framework for other rare diseases,” they wrote.
The scientists noted that further studies could investigate the impact of other variable, “such as geographic location (which could affect standard of care), information on steroid treatment (such as type, duration of treatment, age at initiation) and ventilator use.”