Enlarge / Not so honest drug pricing? (credit: Getty | YinYang)

When nearly 100 drugs became scarce between 2015 and 2016, their prices mysteriously increased more than twice as fast as their expected rate, an analysis recently published in the Annals of Internal Medicine reveals. The price hikes were highest if the pharmaceutical companies behind the drugs had little competition, the study also shows.

The authors—a group of researchers at the University of Pittsburgh and one at Harvard Medical School—can’t say for sure why the prices increased just based off the market data. But they can take a shot at possible explanations. The price hikes “may reflect manufacturers’ opportunistic behavior during shortages, when the imbalance between supply and demand increases willingness to pay,” they conclude.

“There aren’t a lot of industries where if a manufacturer botches the production of a product and is responsible for a reduction in supply that they are able to profit from that… It is the federal government, underinsured, and uninsured patients that are picking up the tab,” co-author William Shrank of the University of Pittsburgh noted in an interview with Bloomberg.