Delineating the spectrum of impairments, disabilities, and rehabilitation needs in methylmalonic acidemia (MMA).

Methylmalonic acidemia patients have complex rehabilitation needs that can be targeted to optimize societal independence and quality of life. Thirty-seven individuals with isolated MMA (28 mut, 5 cblA, 4 cblB), aged 2-33 years, were enrolled in a natural history study, and underwent age-appropriate clinical assessments to characterize impairments and disabilities. Neurological examination and brain imaging studies were used to document movement disorders and the presence of basal ganglia injury. A range of impairments and disabilities were identified by a team of physical medicine experts. Movement disorders, such as chorea and tremor, were common (n = 31, 83%), even among patients without evidence of basal ganglia injury. Joint hypermobility (n = 24, 69%) and pes planus (n = 22, 60%) were frequent and, in many cases, under-recognized. 23 (62%) patients required gastrostomy feedings. 18/31 patients >4 years old (58%) had difficulties with bathing and dressing. 16 of 23 school-aged patients received various forms of educational support. Five of the 10 adult patients were employed or in college; three lived independently. Unmet needs were identified in access to rehabilitation services, such as physical therapy (unavailable to 14/31), and orthotics (unavailable to 15/22). We conclude that patients with MMA are challenged by a number of functional limitations in essential activities of mobility, self-care, and learning, in great part caused by movement disorders and ligamentous laxity. Early assessment, referral, and implementation of age-appropriate rehabilitation services should significantly improve independence and quality of life.

Newborn screening by tandem mass spectrometry for medium-chain Acyl-CoA dehydrogenase deficiency: a cost-effectiveness analysis.

OBJECTIVE: To determine whether newborn screening by tandem mass spectrometry (MS/MS) for medium-chain acyl-CoA dehydrogenase deficiency (MCADD) is cost-effective versus not screening and to define the contributions of disease, test, and population parameters on the decision. METHODS: A decision-analytic Markov model was designed to perform cost-effectiveness and cost-utility analyses measuring the discounted, incremental cost per life-year saved and per quality-adjusted life-year saved of newborn screening for MCADD compared with not screening. A hypothetical cohort of neonates made transitions among a set of health states that reflected clinical status, morbidity, and cost. Outcomes were estimated for time horizons of 20 and 70 years. Probabilities and costs were derived from a retrospective chart review of a 32-patient cohort treated over the past 30 years at the Children's Hospital of Philadelphia, clinical experience with MCADD patient management, patient-family interviews, cost surveys, state sources, and published studies. In addition to older patients who came to medical attention by symptomatic presentation, our patient group included 6 individuals whose MCADD had been diagnosed by supplemental newborn screening. Estimates of the expected net changes in costs and life expectancy for MCADD screening were used to compute the incremental cost-effectiveness ratios. Sensitivity analyses were performed on key input variables, and 95% confidence intervals (CIs) were computed through second-order Monte Carlo simulations. RESULTS: In our base-case analysis over the first 20 years of life, the cost of newborn screening for MCADD was approximately 11,000 dollars(2001 US dollars; 95% CI: <0-33,800 dollars) per life-year saved, or 5600 dollars (95% CI: <0-17,100 dollars) per quality-adjusted life-year saved compared with not screening. Over a 70-year horizon, the respective ratios were approximately 300 dollars (95% CI: <0-13,000 dollars) and 100 dollars (95% CI: <0-6900 dollars). The results were robust when tested over plausible ranges for diagnostic test sensitivity and specificity, MCADD prevalence, asymptomatic rate, and screening cost. CONCLUSIONS: Simulation modeling indicates that newborn screening for MCADD reduces morbidity and mortality at an incremental cost below the range for accepted health care interventions. At the 70-year horizon, the model predicts that almost all of the additional costs of screening would be offset by avoided sequelae.