Substitution and complementarity in the use of health information exchange and electronic medical records

While considerable literature has addressed the separate use of health information systems, limited research has examined how the use of one system changes following the implementation of another. We address this gap in the literature by developing and testing hypotheses about substitution and complementarity in physicians' use of health information exchange (HIE), which merges patient data from multiple sources, following the implementation of a local electronic medical record (EMR) system. The hypotheses are anchored in theories foundational to understanding the motivation for information seeking behaviour. The hypotheses are tested with unique data, recorded in system log files, that describe HIE use by physicians in an emergency department before and after EMR implementation. The findings confirm that system use is characterised by substitution when it is defined dichotomously as whether the system is accessed or not (lower HIE access rates after EMR implementation) and by complementarity when it is defined as the extent of system use (higher volume and duration of HIE use after EMR implementation). Our findings suggest that the information seeking literature has underestimated the explanatory value of the cost-benefit approach and the occurrence of complementarity in system use because of its overreliance on a narrow definition of use.