NEW YORK (Reuters Health) - Having sales representatives from medical device companies at hospitals may influence which products doctors use and ultimately drive up costs, according to a new study from Canada. Researchers found that doctors were more likely to use a company's drug-coated heart stent when one of its sales representatives visited their hospital, which resulted in about a $250 higher bill per case. "We need to evaluate carefully any interactions with medical industry to ensure that we minimize an effect on our decision making process," wrote Dr. Shahar Lavi, the study's lead author, in an email to Reuters Health.