We analyzed data from a large representative sample of US EDs, and found that 46% had implemented electronic medical records (EMRs) in 2005–2006. This compares favorably with results obtained using similar methods for 2001–2002, which estimated that 31% of US EDs had an EMR 
. This improvement may be encouraging, but it has been pointed out that the presence of “any” EMR does not ensure that the EMR's functionalities are relevant to patient safety or other outcomes. In other words, the mere presence of an EMR does not imply “meaningful use” of health information technology 
When we used the classification of Jha and DesRoches, and considered a “basic” system to be the minimum required for “meaningful use,” we found that only 17% of the nation's EDs could claim “meaningful use” 
. Of EDs reporting that they had an EMR system, fewer than 1/3 had a “meaningful” one according to this definition.
Higher-volume EDs were more likely to report at least a “basic” EMR. This makes sense, because purchase of an EMR system would be much more costly on a per-revenue basis for smaller EDs. It can be argued, moreover, that the unintended consequences of EMR adoption, such as increased waiting times, would not vary according to ED size. Thus, cost and other negatives of EMR adoption would seem to weigh more heavily in the risk-benefit calculation for smaller-volume facilities. To our knowledge, this consideration has not been incorporated into current plans to incentivize EMR adoption on a national basis 
We believe that the ED is a particularly important setting for analysis of EMR implementation, and not only because EDs may uniquely benefit from EMRs, due to the urgency of information needs and the lack of long-term relationships between patients and providers. It is also important because EDs may be uniquely vulnerable to the unintended consequences of EMRs. EDs often acquire EMRs but fail to implement them 
. EMRs and related process-of-care changes are expensive, can increase
ED length of stay, and can sometimes impair
patient safety 
We chose to analyze the EDs in our data set according to the classification of Jha and DesRoches, since this schema was used in the two largest national surveys of EMR adoption 
. However, contemplation of these criteria reveals them to be somewhat arbitrary. For example, it is not intuitive that CPOE should be an element of the simplest (“basic”) system, but that display of clinical notes would be an element of a more-advanced system. Our data reveal that many EDs are capable of various electronic functions, but few meet Jha and DesRoches' standards for “basic” or better EMR systems.
Alternative definitions of “meaningful use” could easily be devised. For example, a simple criterion might be implementation of CPOE. This would be attractive not only for its simplicity, but also because CPOE is a prerequisite for checking for errors, cross-reactions, and allergies. Another way to define “meaningful use” might be the ability to display past medical history information, which offers providers critical data about ED patients whom they have never met before. A third definition might rely upon decision support systems. Our data reveal that while the “basic” EMR definition used by Jha 
and DesRoches 
would allow only 17% of US EDs to claim “meaningful use,” a definition based on the availability of CPOE, clinical notes, or any decision support, would allow 21%, 26%, or 40% of EDs to make this claim. This demonstrates that varying the definition of “meaningful use” affects the number of facilities that can claim it (and receive financial rewards from the government and other third-party payers).
Fortunately, the US government's operationalization of the concept of “meaningful use” is nuanced and flexible. The definition is still evolving, but is planned to roll out in three stages 
. In the first stage, eligible providers and hospitals will be graded according to their implementation of roughly 25 functionalities. Stages 2 and 3 would build upon stage 1 functionalities to target specific goals 
. As mentioned above, we are not aware that any consideration of facility volume has been incorporated into these plans.
The principal limitation of our study is its retrospective nature: we were only able to analyze data that had been collected. Furthermore, we were unable to assess EMR interoperability, i.e. use in more than one institution or department, another important feature of “meaningful” EMR use. The scope of our investigation was limited to surveillance, and we did not attempt to measure the effectiveness or cost-effectiveness of ED EMR systems.
In summary, though the proportion of US EDs reporting EMRs is increasing, fewer than half had such systems in 2005–2006. Among those EDs that did have an EMR, there was a great deal of variation in what the EMR systems could do, and any grading system will reward or penalize the nations EDs quite differently, depending on the chosen definition of “meaningful use.” We end on a cautionary note: more is not always better. In the rush to incentivize implementation of EMR systems, we should study not only the rate of technology acquisition, but also the more-subtle questions of implementation, unintended consequences, and cost-effectiveness. If an ED claims to have a given EMR functionality, is that functionality implemented in full 
? Is it truly benefitting the ED's clientele, after accounting for all intended and unintended consequences? To answer these questions, how should the government audit EMR adoption and monitor its effects?