Rare Disease Coverage Decisions Require Ongoing Evidence Review

Because rare disease therapies often launch without all necessary data, payers must rely on expert input and real-world evidence, Susan M. Wescott, RPh, MBA, told The American Journal of Managed Care^® in part 2 of an interview at the Academy of Managed Care Pharmacy Nexus 2026 meeting.

Wescott, a panelist in the session “Payer Evidence and Decision-Making in Rare vs Common Disease Products,” noted that some FDA-approved therapies have been studied in clinical trials involving fewer than 100 or even 20 patients. Recruiting enough patients for these trials is often difficult, she said, because the population is limited and patients vary in age and disease state, with some not meeting eligibility criteria. Experts can also be scarce, Wescott added, requiring health plans’ own experts to reach out to the few clinicians who treat these patients to understand a therapy’s potential impact.

“Just like the cost, we don’t seem to have a choice right now of the type of evidence we’re getting,” Wescott said. “Therefore, it’s very important to continue evaluating along the path of drug development in the real world. So, real-world evidence is very important here, and revisiting our decision every 6 or 12 months to make sure it’s still valid.”

Citing research presented by James D. Chambers, PhD, MPharm, MSc, of Tufts Medicine, during the session, Wescott said nearly all rare disease therapies require prior authorization. Roughly half of these coverage requirements align with the FDA-approved label, but many payers add criteria, such as identifying specific patient subgroups or genetic markers, based on clinical trial data.

Still, she cautioned against creating unnecessary prior authorization burdens that could limit access for families already struggling with a rare condition. These families may travel across the country seeking care and should not have to spend months trying to access potentially life-changing therapies, Wescott noted. As in oncology, a pharmacist carefully reviews each claim for up to an hour rather than relying on automation.

At the same time, payers cannot eliminate prior authorization and coverage criteria altogether when some drugs cost millions of dollars, or hundreds of thousands of dollars annually over a patient’s lifetime. Instead, Wescott said, plans must identify the key criteria that meaningfully inform coverage decisions.

She also questioned whether renewal criteria are necessary when eligibility depends on a genetic marker that is already present. In those cases, the only question plans need to answer at renewal is whether patients are responding to treatment or should be switched to another therapy, Wescott said.

Although plans can take a consistent approach by evaluating the same elements and using standard processes, she noted that full consistency may not be possible, because rare diseases differ widely in how they affect patients’ lives and health care use.

“I think that’s going to lead to some inconsistency, to answer your question honestly,” Wescott concluded.