Effects of laboratory data exchange in the care of patients with HIV.

Background: Electronic health record (EHR) systems are often modified through the addition of new features over time. Few studies have examined the specific effects of such changes. We examined whether implementation of a bidirectional laboratory interface for order entry and data reporting within an existing ambulatory EHR would result in more prompt responses to laboratory indications for antiretroviral therapy (ART) changes or in improved communication with HIV+ patients about relevant laboratory results.