Affiliations: [a] University of Rochester, Rochester, NY, USA | [b] New York State Department of Health, Albany, NY, USA | [c] The University of Iowa, Iowa City, IA, USA | [d] Weill Cornell Medical, New York, NY, USA | [e] Colorado School of Public Health, Aurora, CO, USA
Correspondence:
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Corresponding author: Emma Ciafaloni, 601 Elmwood Avenue, PO BOX 673, Rochester, NY 14642, USA. Tel.: +1 585 273 3432; Fax: +1 585 273 1255; E-mail:[email protected]
Abstract: PURPOSE: We investigated the prognostic utility of onset age at
first signs and symptoms (SS) to predict onset age at loss of ambulation
(LOA) for childhood-onset Duchenne and Becker Muscular Dystrophies (DBMD). METHODS: Our cohort comprised male cases with DBMD
ascertained by the population-based Muscular Dystrophy Surveillance,
Tracking, and Research Network (MD STARnet). Adjusted hazard ratios (HRs) and
95% confidence intervals (CIs) were estimated using Cox proportional
hazards models for associations between onset ages of first SS and LOA.
Covariates controlled for were corticosteroid use, family history of DBMD,
birth year, race/ethnicity, and MD STARnet site. Onset age at first SS was
considered as a continuous and as a categorical variable. RESULTS: A one-year increase in onset age at first SS was
significantly associated with a 10% reduction in annual risk of LOA
(HR = 0.90, CI = 0.87-0.94). Treating onset age at first SS as a categorical
variable yielded a similar association (≥ 5 years: referent; ≥ 3
to < 5 years: HR = 1.36, CI = 1.02-1.81; 18 months to < 3 years: HR = 1.72,
CI = 1.31-2.26; < 18 months: HR = 1.52, CI = 1.14-2.02). CONCLUSIONS: Earlier onset age at first SS is associated
with earlier onset age at LOA and may have clinical utility in
differentiating childhood-onset Duchenne and Becker muscular dystrophies.
