We know that poor usability can lead to disastrous consequences. Think to the recent case of the accidental missile alert in Hawaii.
This is a more rigorous, academic investigation into the negative consequences of poor usability in electronic health records. The study even suggests that bad usability may have caused deaths.
Some 557 (0.03 percent) reports had “language explicitly suggesting EHR usability contributed to possible patient harm,” and among those, 80 caused temporary harm, seven may have caused permanent harm and two may have been fatal.