Disparities in Spinal Muscular Atrophy-Related Mortality in the United States, 2018-2023

Prior SMA mortality studies have shown excess mortality in people with SMA, but the literature lacks data on disparities in SMA-related mortality. This study examined disparities in SMA-related mortality in the United States in the post-treatment era (2018-2023).

This was a population-based study using the CDC Wide-ranging Online Data for Epidemiologic Research (CDC WONDER) database. The International Classification of Disease (ICD), 10th Revision, Clinical Modification codes, G12.0, G12.1, G12.8, and G12.9, were used to identify SMA. The data were stratified by biological sex, race/ethnicity (Non-Hispanic/NH White, NH Black, Hispanic, Asian) and Census regions (West, Northeast, Midwest, South). The analysis was conducted by calculating rate ratios (RR) of age-adjusted mortality rate (AAMR).

There were 821 (45.8% female) SMA-related deaths across the study period. Males were associated with higher AAMR than females (RR = 1.189, 95% CI: 1.035 to 1.366). The SMA-AAMR for NH White individuals was the highest compared to Hispanic individuals (RR = 1.808, 95% CI: 1.420 to 2.300), followed by NH Black and Asian individuals. The West carried the highest AAMR compared to the Northeast (RR = 1.581, 95% CI: 1.263 to 1.978), followed by the Midwest and the South. The age at death distribution showed a bimodal pattern, as follows: 5-14 years and 65-74 years. The infant age group (<1 year) was associated with the highest AAMR compared to all other age groups.

Our findings showed that SMA-related mortality was highest in infants, NH White individuals, the West, and males. These data may assist future efforts to reduce the burden of SMA.