Subspecialty Health Care Utilization in Pediatric Patients With Muscular Dystrophy in the United States.

Background and Objectives: Standards of care exist to optimize outcomes in Duchenne and Becker muscular dystrophy (DBMD), caused by alterations in the DMD gene; however, there are limited data regarding health care access in these patients. This study aims to characterize outpatient subspecialty care utilization in pediatric patients with DBMD. Methods: This retrospective cohort study used administrative claims data from IBM MarketScan Medicaid and Commercial Claims and Encounters Research Databases (2013-2018). Male patients 1-18 years with an ICD-9/10 diagnosis code for hereditary progressive muscular dystrophy between January 1, 2013, and December 31, 2017, were included. Participants were stratified into 3 age cohorts: 1-6 years, 7-12 years, and 13-18 years. The primary outcome was rate of annual neurology visits. Secondary outcomes included annual follow-up rates in other subspecialties and proportion of days covered (PDC) by corticosteroids. Results: A total of 1,386 patients met inclusion-347 (25.0%) age 1-6 years, 502 (36.2%) age 7-12 years, and 537 (38.7%) age 13-18 years. Heart failure, respiratory failure, and technology dependence increased with age (p for all<0.05). The rate of neurology visits per person-year was 0.36 and did not differ by age. Corticosteroid use was low; 30% of person-years (1452/4829) had a PDC ≥20%. Medicaid insurance was independently associated with a lower likelihood of annual neurology follow-up (OR 0.23; 95% CI 0.18-0.28). Discussion: The rate of annual neurology follow-up and corticosteroid use in patients with DBMD is low. Medicaid insurance status was independently associated with a decreased likelihood of neurology follow-up, while age was not, suggesting that factors other than disease severity influence neurology care access. Identifying barriers to regular follow-up is critical in improving outcomes for patients with DBMD.

Health Care Use of Cardiac Specialty Care in Children With Muscular Dystrophy in the United States.

Background Duchenne and Becker muscular dystrophy are progressive disorders associated with cardiac mortality. Guidelines recommend routine surveillance; we assess cardiac resource use and identify gaps in care delivery. Methods and Results Male patients, aged 1 to 18 years, with Duchenne and Becker muscular dystrophy between January 2013 and December 2017 were identified in the IBM MarketScan Research Database. The cohort was divided into <10 and 10 to 18 years of age. The primary outcome was rate of annual health care resource per person year. Resource use was assessed for place of service, cardiac testing, and medications. Adjusted incidence rate ratios (IRRs) were estimated using a Poisson regression model. Medication use was measured by proportion of days covered. There were 1386 patients with a median follow-up time of 3.0 years (interquartile range, 1.9-4.7 years). Patients in the 10 to 18 years group had only 0.40 (95% CI, 0.35-0.45) cardiology visits per person year and 0.66 (95% CI, 0.62-0.70) echocardiography/magnetic resonance imaging per person year. Older patients had higher rates of inpatient admissions (IRR, 1.46; 95% CI, 1.03-2.09), outpatient cardiology visits (IRR, 2.0; 95% CI, 1.66-2.40), cardiac imaging (IRR, 1.59; 95% CI, 1.40-1.80), and Holter monitoring (IRR, 3.33; 95% CI, 2.35-4.73). A proportion of days covered >80% for angiotensin-converting enzyme inhibitors/angiotensin receptor blockers was observed in 13.6% (419/3083) of total person years among patients in the 10 to 18 years group. Conclusions Children 10 to 18 years of age have higher rates of cardiac resource use compared with those <10 years of age. However, rates in both age groups fall short of guidelines. Opportunities exist to identify barriers to resource use and optimize cardiac care for patients with Duchenne and Becker muscular dystrophy.

Increasing Pump Speed During Exercise Training Improves Exercise Capacity in Children with Ventricular Assist Devices.

Exercise rehabilitation during pediatric ventricular assist device (VAD) support aims to improve musculoskeletal strengthening while awaiting heart transplantation (HT). This study aimed to determine whether increasing VAD pump speed during exercise testing and training improves exercise capacity. A single-center cohort study was performed comparing changes in exercise capacity on serial cardiopulmonary exercise testing (CPET) after exercise training at a fixed VAD pump speed (historical cohort from 2014 to 2017) compared with a prospective cohort (2017-2019) who underwent increasing pump speed during exercise training. All children were supported with intracorporeal continuous-flow VAD. Four subjects (13 ± 2.8 years) were included in the historical cohort, and 6 subjects (14 ± 1.7 years) were enrolled in the prospective cohort. Ninety percent had dilated cardiomyopathy, and one had single ventricle Fontan physiology. Baseline maximal oxygen consumption (VO2) was 19 ± 6.3 ml/kg/min. After exercise training with increased pump speed, there was substantial improvement in aerobic capacity (maximal VO2 increased 42% vs. decreased 3%, respectively) and working capacity (maximal work increased 49% vs. 13%, respectively) compared with fixed pump speed. There were no adverse events reported in either the fixed or increased pump speed cohorts. Increasing VAD pump speed during exercise training results in substantial improvement in both physical working and aerobic capacity compared a fixed pump speed in children on VAD support regardless of single or biventricular ventricle physiology. Further study of a larger cohort is needed to validate these findings to improve the approach to pediatric cardiac rehabilitation in this population.