Duchenne Muscular Dystrophy: Time Interval Unchanged from Symptoms to Diagnosis

Among male children diagnosed with Duchenne muscular dystrophy (DMD), the interval of 2.2 years between first signs of DMD and diagnosis is unchanged over time, according to study results published in Muscle & Nerve.

For children (almost exclusively males, as few females are ever symptomatic of DMD whose mutated gene is located in the X chromosome) born up to 40 years before 2001, the average age at diagnosis was about 5 years, and the interval between first signs and diagnosis was 2.5 years, according to data analyzed from a 2009 study from the Muscular Dystrophy Surveillance, Tracking, and Research Network (MD STARnet).

New treatments for DMD demand earlier diagnosis for greatest benefit, so the Centers for Disease Control and Prevention (CDC) and concerned patient organizations have made a push to reduce time to diagnosis. Researchers sought to determine if males born after January 1, 2000 have been diagnosed at an earlier age/if the interval between first signs and diagnosis has changed.

To accomplish this, they conducted a follow-up surveillance study using data from MD STARnet sites in Colorado, Iowa, Western New York State, Piedmont region of North Carolina, South Carolina, and Utah of 221 males with definite or probable DMD diagnosis and no family history, born from January 1, 2000 to December 31, 2015. The primary outcome was the time interval between primary care givers/physicians noticing first signs of DMD and diagnosis.

DNA testing confirmed diagnosis in 96.4% of the study group. Through statistical analysis, researchers determined the mean age of first signs (2.7 years), first creatine kinase (CK) (4.6 years), DNA/muscle biopsy testing (4.9 years), and time from first signs to diagnostic confirmation (2.2 years). They noted that age at first concern, testing, and first specialist visit, “were significantly later among non-Hispanic Black individuals compared to non-Hispanic whites. Additionally, the age at CK testing was significantly later among Hispanic individuals compared to non-Hispanic whites. No other differences in ages by race/ethnicity were found.”

Researchers concluded, “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.”

Disclosure: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.

Reference

Thomas S, Conway KM, Fapo O, et al. Time to diagnosis of Duchenne muscular dystrophy remains unchanged: Findings from the Muscular Dystrophy Surveillance, Tracking, and Research Network (MD STARnet), 2000-2015. Muscle Nerve. Published online March 21, 2022. doi:10.1002/mus.27532