Trevor Richter is the current director of CADTH common drug review, and he wrote an article in 2018, “Characteristics of drugs for ultra-rare diseases versus drugs for other rare diseases in HTA submissions made to the CADTH CDR”. It's available on Orphanet.
In it, he acknowledged the higher rate of negative HTA recommendations for ultra-rare disorders, and suggested it may be warranted to apply different standards when evaluating these therapies. Do you agree with Mr. Richter's assessment? If so, what is CADTH doing?