DMD Diagnosis Takes as Long Today as Decades Ago, Study Finds
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Despite broad initiatives seeking improvements, the time it takes an individual with Duchenne muscular dystrophy (DMD) to get a correct diagnosis has remained largely unchanged over the past three decades, a study reports.
It still takes more than two years, on average, from the time symptoms are first noticed to the time patients get a diagnosis — delays that cost precious time in treatment, according to researchers.
“The time to diagnosis of DMD among males without family history remains unchanged and results in lost opportunities for timely genetic counseling, implementation of standards of care, access to newly approved disease modifying medications, and participation in clinical trials,” they wrote.
Moreover, the study showed “persistently later” diagnoses among minority patients.
The study, “Time to Diagnosis of Duchenne Muscular Dystrophy Remains Unchanged: Findings from the Muscular Dystrophy Surveillance, Tracking, and Research Network (MD STARnet), 2000-2015,” was published in the journal Muscle and Nerve. The work was funded by the Centers for Disease Control and Prevention (CDC), a U.S. government health protection agency, among others.
The earlier in life that patients with DMD receive a correct diagnosis of their condition, the sooner they can start treatment and supportive care. Such care generally is tied to better outcomes in the long run. As more and more new treatments become available, the importance of an early diagnosis is only increasing, according to researchers.
In a prior study published in 2009, researchers at the CDC had assessed the age at diagnosis for DMD patients born from 1982 through 2000. They found that the mean age at diagnosis was just under 5 years old, and that there were significant diagnostic delays. The researchers had noted that the “first signs or symptoms [of DMD] were noted at a mean age of 2.5 years.”
At that time, the CDC put in place new initiatives aiming to shorten the time to diagnosis. Moreover, on its website, the CDC links to a tool for parents concerned about their child’s physical development. Advocacy groups also have called for improved DMD diagnoses.
Now, researchers analyzed the age at diagnosis for 221 males, born from 2000 to 2015, with a definite or probable diagnosis of DMD.
The patients were followed at sites across the U.S., in Colorado, Iowa, New York, North Carolina, South Carolina, and Utah. In terms of race and ethnicity, 67.9% were non-Hispanic white individuals, 6.8% were non-Hispanic Black patients, and 16.7% were Hispanic individuals; the rest were unknown. None of the patients had a family history of DMD.
Among all of the patients, the mean age at which caregivers first noticed symptoms was 2.7 years. The mean age at which patients first underwent testing for creatine kinase (CK), a marker of muscle damage, was 4.6 years.
The researchers noted that ages at CK testing were significantly later among non-Hispanic Black patients compared with non-Hispanic white individuals. Age at first concern and initial visit to a specialist clinic also were markedly later for Black patients.
The mean age when patients underwent confirmatory DMD diagnostic testing — genetic testing or muscle biopsy — was 4.9 years. That is more than two years after the first onset of symptoms, on average, the researchers noted.
Non-Hispanic whites were younger at a definitive diagnosis than Hispanics and non-Hispanic Blacks.
“In this study we have demonstrated a persistent 2.2-year time interval between first signs and symptoms of DMD and diagnostic confirmation and an average age of 4.9 years at diagnosis among males without a family history of DMD in selected geographical regions in the United States,” the researchers concluded.
“This interval between symptom onset and diagnosis has not changed in the past three decades and is persistently later in minority groups,” they added.
The team highlighted that testing children at birth for the disorder — called newborn screening — could improve the speed and accuracy of DMD diagnosis.
“Newborn screening (NBS) for DMD could ensure early diagnosis and help to mitigate racial disparities that currently exist,” they wrote. “The unchanged time interval to diagnosis, recent FDA [U.S. Food and Drug Administration] approval of four … drugs, and preliminary results of successful gene transfer in children with DMD age 4 to 7 years have underscored the potential value of NBS for DMD.”
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