More than 2 years separate DMD diagnosis in Black, white youth

Five of 7 clinical milestones for managing disease occurred later in Black children

Joana Vindeirinho, PhD avatar

by Joana Vindeirinho, PhD |

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Five of seven clinical milestones in managing Duchenne muscular dystrophy (DMD) occurred significantly later for Black males than for white males, a new study reports.

These gaps appeared to stem from the initial delays in the first evaluation, which occurred for Black children 2.3 years later than for white and Hispanic boys.

“The 2.3-year difference in initial evaluation among non-Hispanic Black males compared to both non-Hispanic white and Hispanic males is notable and represents a potential target for intervention to ameliorate delays in receipt of recommended services,” the researchers wrote in the study, “Racial and ethnic differences in timing of diagnosis and clinical services received in Duchenne Muscular Dystrophy,” which was published in Neuroepidemiology.

Two milestone delays — for offering and initiating corticosteroid therapy — were found for Hispanic boys compared with white boys, but the results were less consistent.

Researchers and clinicians have established that an early diagnosis is crucial for the timely treatment and care of children with DMD, which improves their disease outlook over time.

There are well-known disparities between races and ethnicities regarding access to healthcare and use, and their effects on diagnosing and treating patients have been studied in several diseases. Some studies have assessed disparities in people with DMD, but have focused on one or more aspects of clinical services, such as diagnosis, health service use, or steroid treatment.

“Barriers to obtaining health care may lead to delayed, reduced frequency, or reduced quality of interactions between a young child with DMD and the healthcare system,” said the researchers, who defined seven important clinical milestones for DMD and assessed the timing of each one both individually and in relation to the initial evaluation and diagnosis. Their work was supported by the U.S. Centers for Disease Control and Prevention.

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Assessing disparities in clinical milestones

The seven milestones assessed were initial evaluation, first visit to a neurology or neuromuscular specialist, earliest diagnostic confirmation by genetic testing or muscle biopsy, first electrocardiogram or echocardiogram (heart tests), first time corticosteroid treatment was offered, start of corticosteroid treatment, and first pulmonary function test.

Researchers estimated the age at which 50% of the group reached each milestone. They then compared the timing of each milestone in a group in relation to the non-Hispanic white group, which was used as the reference value. This analysis was repeated using the time between initial evaluation or diagnosis and each subsequent milestone to account for the impact of those two important steps on managing disease progression.

The study included collected data from 682 males diagnosed with DMD, born between Jan. 1, 1990, and Dec. 31, 2010. Data were collected from eight sites of the Muscular Dystrophy Surveillance Tracking and Research Network (MD STARnet).

Efforts to address barriers to early evaluation and diagnosis for non-Hispanic Black children with DMD may promote more timely initiation of recommended disease monitoring and interventions.

More than half (421, or 61.7%) of the boys were non-Hispanic white, followed by Hispanic (140, 20.5%), other race/ethnicity (e.g., Asian, Native American, Pacific Islander, and other groups too small to be a separate category; 72, 10.6%), and non-Hispanic Black (49, 7.2%).

For the Black boys, five of the seven milestones — initial evaluation, first visit to a specialist, diagnosis, and first offer of and start of treatment with corticosteroids — were significantly delayed, compared with white boys. In particular, the age at the initial evaluation for Black boys was estimated to be 6, compared with 3.7 for white and Hispanic boys, and 4.1 for boys of other races/ethnicities.

When the analysis accounted for the timing of the initial evaluation and diagnosis, the delays for the remaining milestones were no longer significant. This finding suggests the timing of the initial evaluation and diagnosis had a strong impact on subsequent milestone delays for Black youth.

“Efforts to address barriers to early evaluation and diagnosis for non-Hispanic Black children with DMD may promote more timely initiation of recommended disease monitoring and interventions,” the researchers wrote.

Results mixed for Hispanic boys, other races

Delays were also seen in some milestones for Hispanic boys. Although they were initially evaluated and diagnosed at nearly the same age as white boys, there were significant delays in the age when they were first offered corticosteroids and when corticosteroid treatment started compared with white boys.

When accounting for timing of the initial evaluation and diagnosis, results were mixed for Hispanic boys. While the first offer of corticosteroids was still significantly delayed compared with white boys, it wasn’t for starting corticosteroid treatment. Also, the first pulmonary function test occurred significantly earlier in Hispanic boys than white boys.

Boys of other races/ethnicities seemed to have the least differences in timing with the white group. The start of corticosteroid treatment showed the only significant difference between this group and the white group, and no significant differences were found once the analysis accounted for the timing of the initial evaluation and diagnosis.

“Our findings could inform the development of targeted interventions that promote earlier evaluation and diagnostic confirmation of DMD, especially for non-Hispanic Black individuals, which may allow for timely initiation of recommended disease monitoring and interventions,” the researchers wrote.

Although the study couldn’t assess the drivers behind these delays, the researchers said socioeconomic factors affecting healthcare access and use, the ability of doctors to provide effective care while keeping in mind the social, cultural, and linguistic needs of patients), and genetic differences between groups could play a role.