Rare Neurological Diseases: Spinal Muscular Atrophy and Huntington's Disease - Episode 16
Surya Singh, MD: Payers generally defer to panels of experts to formulate their diagnostic criteria—it will become all a part of the medical policies and clinical criteria that will feed into the prior authorization process. For almost every treatment for a rare disorder, there are specific criteria that a payer will go through. There’s some deviation from this depending on how the particular treatment is reimbursed, whether it’s on the pharmacy benefit or the medical benefit, but with very few exceptions, they all go through a prior authorization process that has a first level, second internal level, and then an external review if an appeal gets to that point where a denial has been upheld through the first 2 levels.
But those criteria are part of the medical policy and are generally developed in close consultation for rare disorders with a panel of external experts. It can number anywhere from 2 people to 10 people depending on the disease, how much variability there is, the severity, and so on, at the time of diagnosis. It also depends on what the genetics are, what biomarkers are available, and all those types of factors. The knowledge incumbent in the payer is generally not very deep for rare disorders, but it gets deeper through this consultation when new therapies come about with external experts.
When nusinersen was first approved for the market in December of 2016, there was a lot of attention on 2 factors. One was, what type of SMA [spinal muscular atrophy], clinically, did the patient have. Second, how many SMN2 copies did they have. As time wore on from that initial period—working with several dozen different plan sponsors, payer organizations, and understanding what their policies were—attention fell away from the number of copies. Because the number of copies doesn’t necessarily translate, it’s really a range for each type, and it doesn’t translate directly into what type of spinal muscular atrophy is ultimately diagnosed by their treating specialist.
The criteria now, the type of SMA is mainly dictated by age of onset, which age of onset is very important, but there are age ranges, and ranges for a reason. So there’s clinical judgment applied by the treating specialist in making the designation of which type of SMA the patient is ultimately diagnosed with that is informed by their motor milestones and their number of SMN2 copies. Over time, what’s evolved is there’s more attention paid to the type of SMA that the patient has been diagnosed with than anything else. That said, there’s still variability. There still are some plans that are asking for the number of SMN2 copies, asking for documentation of that result and so on, as part of their aforementioned prior authorization, or PA process.