Characterization of Adult Patients With SMA Treated in US Hospital Settings: A Natural History Study in the Premier Healthcare Database

BACKGROUND: Spinal muscular atrophy (SMA) is a rare genetic disease characterized by progressive muscular weakness and atrophy resulting from motor neuron degeneration. Limited information is available on disease progression among older SMA patients, particularly adults. OBJECTIVE: This study sought to characterize the natural history of SMA among adult patients in US hospital settings through the assessment of symptoms, complications, costs, and healthcare resource utilization (HRU) over 3 years before the availability of disease-modifying therapies. METHODS: The study population included adult (≥18 years) patients with inpatient and/or hospital-based outpatient discharge records and ≥2 primary or secondary SMA ICD-9 codes ≥30 days apart in the Premier Healthcare Database during the main study period (2007–2014). Index date was the date of the first SMA ICD-9 code. The frequency of SMA-related symptoms and complications was assessed 1 year preindex through 2 years postindex to characterize disease progression. Costs and HRU were also assessed across the study period. RESULTS: A total of 446 adult patients from 337 US hospitals met inclusion criteria for these analyses. All evaluated SMA-related symptoms and complications increased steadily over time, from 1 year preindex to 2 years postindex both overall and in each age group. Adult patients with SMA had increasing total costs and HRU over the 3-year study period: total costs were $1,759 preindex and $12,308 by 2 years postindex. CONCLUSIONS: Findings are consistent with increasing disease burden over time and support the progressive nature of SMA for adult patients with hospital interactions.