Publications

Recently, drug transporters have emerged as significant modifiers of a patient's pharmacokinetics. In cases where the functioning of drug transporters is altered, such as by drug-drug interactions, by genetic polymorphisms, or as evidenced in knockout animals, the resulting change in volume of distribution can lead to a significant change in drug effect or likelihood of toxicity, as well as a change in half life independent of a change in clearance. Here, we review pharmacokinetic interactions at the transporter level that have been investigated in animals and humans and reported in literature, with a focus on the changes in distribution volume. We pay particular attention to the differing effects of changes in transporter function on the three measures of volume. Further, trends are discussed as they may be used to predict volume changes given the function of a transporter and the primary location of the interaction. Because the liver and kidneys express the greatest level and variety of transporters, we denote these organs as the primary location of transporter-based interactions. We conclude that the liver is a larger contributor to distribution volume than the kidneys, in consideration of both uptake and efflux transporters. Further, while altered distribution due to secondary interactions at tissues other than the liver and kidneys may have a pharmacodynamic effect, these interactions, at least at the blood-brain barrier, do not appear to significantly influence overall distribution volume. The analysis provides a framework for understanding potential pharmacokinetic interactions rooted in drug transporters as they modify drug distribution.

OBJECTIVE Electronic health records (EHRs) have the potential to advance the quality of care, but studies have shown mixed results. The authors sought to examine the extent of EHR usage and how the quality of care delivered in ambulatory care practices varied according to duration of EHR availability. METHODS The study linked two data sources: a statewide survey of physicians' adoption and use of EHR and claims data reflecting quality of care as indicated by physicians' performance on widely used quality measures. Using four years of measurement, we combined 18 quality measures into 6 clinical condition categories. While the survey of physicians was cross-sectional, respondents indicated the year in which they adopted EHR. In an analysis accounting for duration of EHR use, we examined the relationship between EHR adoption and quality of care. RESULTS The percent of physicians reporting adoption of EHR and availability of EHR core functions more than doubled between 2000 and 2005. Among EHR users in 2005, the average duration of EHR use was 4.8 years. For all 6 clinical conditions, there was no difference in performance between EHR users and non-users. In addition, for these 6 clinical conditions, there was no consistent pattern between length of time using an EHR and physicians performance on quality measures in both bivariate and multivariate analyses. CONCLUSIONS In this cross-sectional study, we found no association between duration of using an EHR and performance with respect to quality of care, although power was limited. Intensifying the use of key EHR features, such as clinical decision support, may be needed to realize quality improvement from EHRs. Future studies should examine the relationship between the extent to which physicians use key EHR functions and their performance on quality measures over time.

OBJECTIVE Electronic health records (EHRs) have potential to improve quality and safety, but many physicians do not use these systems to full capacity. The objective of this study was to determine whether this usage gap is narrowing over time. DESIGN Follow-up mail survey of 1,144 physicians in Massachusetts who completed a 2005 survey. MEASUREMENTS Adoption of EHRs and availability and use of 10 EHR functions. RESULTS The response rate was 79.4%. In 2007, 35% of practices had EHRs, up from 23% in 2005. Among practices with EHRs, there was little change between 2005 and 2007 in the availability of nine of ten EHR features; the notable exception was electronic prescribing, reported as available in 44.7% of practices with EHRs in 2005 and 70.8% in 2007. Use of EHR functions changed inconsequentially, with more than one out of five physicians not using each available function regularly in both 2005 and 2007. Only electronic prescribing increased substantially: in 2005, 19.9% of physicians with this function available used it most or all the time, compared with 42.6% in 2007 (p < 0.001). CONCLUSIONS By 2007, more than one third of practices in Massachusetts reported having EHRs; the availability and use of electronic prescribing within these systems has increased. In contrast, physicians reported little change in the availability and use of other EHR functions. System refinements, certification efforts, and health policies, including standards development, should address the gaps in both EHR adoption and the use of key functions.