Medicaid spending and utilization of gene and RNA therapies for rare inherited conditions.

Gene and RNA therapies are promising treatments for many rare diseases. Pediatric populations that could benefit from these drugs are overrepresented among state Medicaid programs. Using Medicaid State Drug Utilization Data, we examined Medicaid spending and utilization of rare disease gene and RNA therapies. Between 2017 and 2022, the number of available gene and RNA therapies increased from 3 to 13, yearly Medicaid spending increased from $148.3 million to $879.7 million, and the number of yearly treatments (a proxy for number of patients) increased from 327 to 1638. Nearly all spending was attributed to spinal muscular atrophy (SMA) and Duchenne muscular dystrophy drugs. States participating in Medicaid pooled purchasing initiatives had 39% higher treatments per 100 000 enrollees with no differences in spending. Compared to states without a carve-out, states that carved SMA drugs out of managed Medicaid contracts had higher utilization (54%). Spending among carve-out states varied according to managed care enrollment, being higher for those with <80% of enrollees in managed care as compared with those with ≥80% of enrollees in managed care. This suggests that multi-state purchasing initiatives and managed care carve-outs can help increase access to gene and RNA therapies among Medicaid beneficiaries, but it is unclear if these strategies are effective at managing spending.