Rare disease advocates may have to fight harder for attention. An overview by Regulatory Focus shows that the US metric for rare diseases—a condition affecting 200,000 or fewer patients—is working against the rare disease community because the US population continues to rise.

RF says the problem is that the 1983 threshold meant that .085% of the population was affected by a rare disease, but that number now represents .064%, which means “any new additions through population growth would cause it to no longer be ‘rare’ under the Orphan Drug Act.”

This in turn means companies would have even less of an incentive to look into these conditions because they would not be able to take advantage of tax incentives and seven years of exclusivity.

RF points out that the EU uses a population percentage as the threshold, classifying rare disease as those affecting .05% of the population, and asks if this should be something the US should pursue.