Respiratory function, evaluation, and treatment in individuals with myotonic dystrophy in the MD STARnet



Poster Number: V314


Amy Moore, PhD, RTI International, Jonathan Suhl, PhD, University of Iowa, Joyce Alese, Centers for Disease Control and Prevention, Jennifer Beverly, RTI International, Kristin Conway, PhD, University of Iowa, Michael Enger, RTI International, Christine Hill, RTI International, Peter Kang, MD, Paul and Sheila Wellstone Muscular Dystrophy Center, University of Minnesota Medical School, Katherine Mathews, MD, FAAN, University of Iowa, Helena Molero, University of Minnesota, Paul Romitti, PhD, University of Iowa, Shiny Thomas, New York State Department ofHealth, Anne-Lyne Verella, RTI International, James Howard, MD, University of North Carolina, Chapel Hill, Nedra Whitehead, MS, PhD, RTI International, Holly Peay, PhD, RTI International

Respiratory care and outcomes are under-studied in myotonic dystrophy (DM). Routine monitoring of respiratory health is recommended by care guidelines. We ascertained individuals with clinical or genetic confirmation of either Type 1 (DM1) or Type 2 (DM2) DM who lived in and received neuromuscular care in one of six Muscular Dystrophy Surveillance, Tracking, and Research Network (MD STARnet) regions during 2008-2016, and who were newly diagnosed during that time period. We abstracted information on respiratory testing (forced vital capacity (FVC), maximal inspiratory and expiratory pressures, cough peak flow, and sleep studies), respiratory-related care (non-invasive positive pressure ventilation (NIPPV)), and specialist visits (pulmonologist, respiratory therapist, sleep specialist), from neuromuscular clinic records. We identified 363 individuals with DM1 and 77 with DM2; 46.6% were male. Fewer than half had any of the selected respiratory tests (40.0%) or a respiratory specialist consultation (22.7%) noted in their neuromuscular clinic records. Individuals with DM1 were more frequently seen by a pulmonologist than those with DM2 (18.5% vs 7.8%), but both groups had similar frequencies of receiving any type of respiratory testing (40.8% vs 36.4%, respectively). A minority of individuals were found to have respiratory abnormalities, including FVC <80% of predicted (19.5%) and use of NIPPV (27.3%). However, among those recorded as ever having their FVC evaluated, 74.8% of those with DM1 and 33.3% with DM2 had at least one FVC value < 80% of predicted. Despite low levels of testing among our population-based cohort of recently diagnosed individuals with DM1 or DM2, a substantial proportion of those with respiratory testing had evidence of below-normal function. Possible explanations for the low frequency of pulmonary evaluations are that individuals are selectively tested based on reported clinical symptoms, or that individuals are unable to perform the selected tests.