HOW MANY ZEBRAS ARE THERE?

Reliable and accurate medical literature is essential for patients with rare diseases (affecting ~400 million people globally), their advocates, and caregivers, and health-care professionals.

In this paper, we quantified the number of English-language publications on rare diseases in PubMed from 2009 to 2018. The result? Of the 10,882,681 articles published, 14,202 (0.13%) mentioned the MeSH term “rare disease” in the title or abstract.

Our conclusion: The number of high-quality medical publications on rare diseases is not commensurate with their overall prevalence and there are access barriers, highlighting an unmet need in medical literature that would benefit all stakeholders.