Duke 2008 | ASHE | Equity and Efficiency in Health and Healthcare

Background: Electronic medical records (EMR) are widely believed to improve efficiency, quality of care, and patient safety in ambulatory care. Expert opinion has posited that ambulatory computerized physician order entry (CPOE) can reduce drug utilization by 15% (Wang et al., 2003). Systematic reviews document that clinical decision support can lower the risk of potential medication errors by 55% (Kaushal et al., 2003). However, these findings come from only a few research locations and may not be generalizable to community settings with commercial software (Chaudrhy et al, 2006). Theoretical Framework: Our understanding of the impact of EMR on physician prescribing patterns can be informed by theories of information and physician learning. Electronic prescribing may provide access to a patient's medication list, formulary coverage of generics and preferred brands, as well as automated tools for screening potential medication errors. This information may alter physician prescribing patterns by lowering uncertainty in the treatment decision, increasing physician utility by lowering the risk of malpractice claims, increasing patient utility by lowering out-of-pocket expense, and increasing patient welfare by reducing the risk of adverse drug events. Objectives: The objective of the study is to estimate the effect of EMR on physician prescribing patterns in ambulatory care. We examine the relationships between EMR functionality (electronic prescribing, clinical reminders, physician clinical notes) and three sets of measures: 1) drug utilization (number of Rx, new vs. continued); 2) prescribing decisions within therapeutic class (probability of multi-source, medication age); and 3) risk of medication error (potential drug-drug interaction (DDI), potential drug-disease contraindication (DDC)). We test whether these effects vary by physician specialty and by therapeutic class. Data and Methods: The study uses data from the 2005 National Ambulatory Medical Care Survey (NAMCS), a nationally-representative survey of patients' office visits to U.S. nonfederal, office-based physicians. The NAMCS includes detailed information on patient demographics and risk factors, physician practice characteristics (including EMR adoption), as well as specific medications prescribed during the patient visit. We matched medication names to the 2007 First DataBank National Drug Data File, which includes information on multi-source status, medication age, as well as potential DDI and DDC. We specify generalized linear models that account for the complex survey design and use generalized estimating equations estimation to address clustering of patients within physician. Results and Implications: The primary results of the study are the marginal effects of EMR functionality on overall drug utilization, use of generics, use of older therapeutic substitutes, and risk of potential medication errors. These estimates can be used to quantify the magnitude of cost savings and reductions in risk of medication error associated with EMR functionality. Since our study is based on a nationally-representative sample of office-based physicians, our findings should be fully generalizable and can inform managers and policymakers of the impact of EMR on physician prescribing patterns in ambulatory care.