Study Finds Rare Diseases Still Underrepresented in Medical Journals

Data presented at the 2019 National Organization for Rare Diseases (NORD) and Orphan Products Breakthrough Summit illustrated the stark reality when it comes to the amount of literature published on rare diseases.

Results of a literature review found that despite rare disease populations making up 6 to 8% of the world’s population, it accounted for less than 0.2% of more than 10 million publications in medical literature.

With more than 7000 rare diseases and healthcare providers often relying on peer-reviewed journals for information, investigators from rareLife Solutions conducted a retrospective analysis of literature in PubMed over a 10-year span. With the goal of assessing the availability and amount of data, investigators performed a search of all articles with the term “rare disease” or “orphan disease” from 2009 through 2018.

Investigators noted the search was limited to those focusing on humans and were published in English. Additional searches and analyses were also performed to confirm the validity of search strategy and to provide detailed analyses based on specific timeframes within the study period.

From 2009 through 2018, a total of 10,882,681 publications were identified and 14,202 (0.13%) met investigators criteria for pertaining to rare disease. An increase was noted over time in rare disease publications—accounting for 0.106% of total publications in 2009 and 0.146% in 2018.

In an additional analysis assessed open access of 100 randomly-selected sample articles over 5-year periods during the study. This analysis found just 20% of articles from 2009 to 2013 and 33% from 2014 to 2018 were published in open-access journals. In comparison, 63% and 64%, respectively, of articles during from those time periods were published in pay-for-access journals.

In their conclusion investigators pointed out the disparity of published literature based on global prevalence by comparing it to type 2 diabetes which has a prevalence of 8.5% and represents 3% of published literature. Additionally, only 1 of 200 patients sampled in an additional analyses included contributions from patients, advocates, and caregivers.

Investigators noted multiple limitations within their study that could have impacted the results of the analyses. Limitations included only searching a single database, limiting articles to those published in English, and the small sample sizes used for detailed analyses.

This study, “How Many Zebras Are There and Where Are they Hiding in Medical Literature? A Literature Review of Publications on Rare Diseases,” was presented at NORD Summit 2019.