Critical laboratory results are signs of major perturbations of key physiologic systems. If patients with such results are not treated promptly and appropriately, organ damage or death may ensue. In this study we found that communicating critical laboratory results directly to the responsible provider decreased the time until an appropriate treatment was ordered, and there was also a trend toward a decreased duration of the life-threatening condition. The effect of the system was present even when the result was communicated to the patient's floor via the laboratory's telephone-based critical reporting procedures and was more pronounced when the result met complex criteria not communicated by standard procedures.
The effect of the intervention was probably due to the fact that the patient's key provider received the information directly, with the pertinent data highlighted and in a context that made ordering the correct treatment easier. Although no difference in adverse event rates was seen, there was a trend toward decreased mortality in the intervention group, and we did not design the study to have sufficient power to identify differences in adverse event rates. Moreover, this is a situation in which improved process can be expected to decrease adverse event rates in the long term. Also, their responses to the attitudinal question indicated that physicians felt the automatic alerts were important.
When used to evaluate and communicate patient data, advanced information technologies can add value in many ways. Currently, hospital laboratories routinely only use single value thresholds as critical indicators,15
because other data are not readily available. In contrast, if a comprehensive clinical database is present, the computer can also detect such events as changes in laboratory results over time and laboratory results that are serious if patients are taking certain medications (drug-laboratory interactions) or have a specific condition such as renal failure. These complex situations are more specific and may be more meaningful than simple thresholds.
Computers also can facilitate response to alerting situations by presenting the information in a suitable context. While it is useful to know that a patient has a critically low serum potassium value, it is even more useful to know that the patient also is receiving high doses of furosemide and digoxin. Presenting information in a suitable context is especially important in cross-coverage situations where the responsible provider may be unfamiliar with the involved patient.26
A background alerting application, such as that described in this study, provides a useful counterpart to reminders embedded in order entry applications.27,28
Reminders embedded in applications can be presented in real time to clinicians using interactive applications on a computer workstation. Background alerts are triggered by data that enter the computer system from other automated systems, so special notification procedures are required to communicate the information to the clinician.
Several nontrivial prerequisites are needed to develop an alerting system such as the one described here. First, the data needed to make the decisions (inferences) must be available electronically on a common computing platform. The alerts in this study made use of laboratory results, medication orders, and patient demographics in our integrated patient database. Most institutions do not yet have physicians writing orders electronically29
; however, almost all have laboratory data available and many have patient medication data available in the hospital pharmacy system.
Second, interfaces between the decision-making systems and notification systems (e.g., paging and electronic mail systems) also are necessary. Such interfaces are becoming technically easier and more widespread.
Third, it can be difficult to determine which provider to notify. Such “coverage list” applications are not yet in widespread use but are essential if information technology is to fulfill its potential to enhance communication. In this study, the computer contacted the covering house officer directly and had methods to follow up if the house officer did not respond to the notification. In contrast, Tate et al.7
displayed the alert message when the patient's data were reviewed, and Rind et al.17
sent e-mail messages to physicians who had previously reviewed the patient's data. Providing laboratory personnel with access to the coverage information would not necessarily add efficiencies, because the technologists' workflow would be interrupted if they have to page a physician, wait for a response, and remember to contact someone else if no response were received. Future applications of automated notification technology may require a system to identify and send messages to such individuals as the patient's primary care physician, referring physician, or other health professional.
Fourth, it is time consuming to decide which events are worthy of automated pages, automated e-mail messages, or other special communication methods. Evidence from the literature to inform such choices is limited, and acquiring this knowledge from experts may be arduous. Tate et al.17
spent more than a year in a formal consensus development process with intensivists to determine which events merited alerts. Although we were able to customize their knowledge base for our institution, we spent significant time specifying new rules. The Arden Syntax,30
which specifies a standard form for medical logic, may allow knowledge developed through consensus at one institution to be more easily reviewed and used elsewhere. Standardization of the representation of medical concepts31
and medical vocabularies32
will also facilitate transfer of electronic knowledge.
Further enhancements to the system are possible. For example, we have added rules that notify physicians about a low platelet count in a patient who is receiving a platelet antagonist and about administration to a patient with renal failure of a medication that should be avoided in that condition. Also, we have added the ability to “retract” an alert. This is necessary if data are entered incorrectly, an alert is generated, and the data are subsequently corrected.33
Physicians continue to be comfortable with the system; in a later analysis, physicians said they would take action in 70 percent of the alerts, and they in fact took action directly from the review screen in 39 percent of the alerts.21
The discrepancy between the numbers is probably due to situations where patients must be examined before an action can be taken.
If the number of rules in such systems expands, care will have to be taken not to overload physicians with alerts. Some systems, such as one in use at the University of Utah Medical Center, permit physicians to “subscribe” to rules in which they are interested (Pierre Pincetl, MD, oral communication, Nov 1997). Also, as data become increasingly available in electronic form, alerting rules can increase in specificity. For example, if a woman is known to be pregnant, she could have a different alerting value for glucose than other patients.
This study has several limitations. The work was carried out at one institution, so the results may not be generalizable to other settings or institutions. Also, we found no significant change in patient outcome as a result of the intervention, although the study was not designed to have sufficient power to detect such differences. Finally, we tested the intervention only with the subset of the critical laboratory results we felt were most important to treat urgently; although there may be many opportunities to use a system such as this to improve care, the effect may differ if other laboratory results are used. We also excluded from this analysis alerts that did not definitely require a response by the physician (e.g., false positives, alerts for patients whose status was DNR, and repeat alerts). This was legitimate because this study examined the impact of the alerting system on treatment delays. Future evaluations of alerting systems should take all alerts into account and determine how often they are deemed useful.
We conclude that the automated alerting system decreased the time it took for physicians to respond to critical laboratory results. Improvements in patient outcomes should follow. Physicians thought that the communicated information was important. Information technologies can help clinicians detect important abnormalities in the flood of data they continually receive.