Medical Order Entry System – CPOE – Laboratory Orders

Medical Order Entry System - CPOE - Laboratory Orders


Medical Order Entry System – CPOE



Computerized physician order entry (CPOE) is a Medical Order Entry System. It refers to the process of physicians entering and sending treatment instructions – including medication, laboratory, and radiology orders – via a computer application.
The primary responsibility for ordering, is left to clinicians. However, without sufficient support in test selection, clinicians face several challenges, perhaps the most significant of which is that the menu of available tests has expanded, in both number and complexity, particularly with new molecular assays. Compounding the expanding menu are time pressures placed on physicians. Most clinicians simply cannot be expected to stay up-to-date with every complex test and diagnostic algorithm outside their specialty. Clinicians may compensate for not knowing which test to order by ordering many tests, some of which are unneeded, putting patients at risk for wasteful or even harmful follow-up care. Alternatively, clinicians may fail to order needed tests, leading to delayed or incorrect diagnoses.
Medical Order Entry systems that allow ordering to directly input laboratory test orders, known as Computerized physician Order Entry (CPOE) systems, may provide a key leverage point to improve laboratory test ordering efficiency, laboratory utilization, and patient care. Appropriate implementation and use of CPOE systems can help to overcome many of the aforementioned challenges to test selection.
The article is based upon a combination of our experience with the implementation and use of CPOE systems and a review of the literature. Representative studies are cited to illustrate or support key concepts and provide examples of CPOE strategies and benefits.


Laboratory ordering systems are most commonly deployed in hospital and encompass most clinical laboratory testing areas, including chemistry, hematology, and microbiology. Most of the CPOE benefits have been reported in inpatient and emergency department settings. The use of laboratory CPOE systems for outpatients presents a unique set of challenges stemming from the heterogeneity of outpatient practice. For example, practices may lack practice management systems and other electronic health systems capable of interfacing with the CPOE system. For practices that do not draw specimens within the practice, CPOE systems may also need to communicate laboratory orders to phlebotomy centers. Finally, in the outpatient setting, days or weeks may elapse between the time an order is placed and when the specimen is collected. To meet the challenge present in the outpatient setting, some laboratories, particularly large commercial ones, have developed web-based portals that allow outpatient clinicians to order tests and view results. Web-based portals permit clinicians to input laboratory orders and print requisition and tube labels onsite or electronically transmit orders to phlebotomy centers.


Providers in CPOE systems are typically physicians, but in many health systems, nurse practitioners and other authorized providers are also able to enter orders. While this article is devoted primarily to the laboratory aspects of CPOE systems, it is important to recognize that the functionality of most CPOE systems extends well beyond laboratory orders. Advanced systems have functionality encompassing virtually every type of order, including medications, nursing instructions, imaging, consultations, and diagnostic procedures.
Order Entry System - Laboratory Orders - CPOE


One of the key determinants of the utility and functionality of a given laboratory CPOE system is the ability of the system to interact with other portions of the electronic health record. All CPOE systems must interface with other electronic health record systems to receive up-to-date demographics and visit information. A key additional system that the laboratory CPOE system may interface with is the Laboratory Information System (LIS). The interoperability to the LIS permits the CPOE system to send orders directly to the LIS. This is typically accomplished using an electronic interface based on Health Level 7 (HL7) interfacing standards. HL7 messages are of a standard format and are used widely to communicate certain types of laboratory data, including orders and results, between information systems.


The CPOE system directly transmits the order into the LIS, creating a LIS order at the time of CPOE test ordering. In addition, the LIS is able to generate bar-coded specimen labels proximate to the time of specimen collection. The labels produced for bedside labeling correspond to the LIS order, so in-laboratory relabeling is not necessary. Label printers can be located in patient rooms, on handheld devices, or at a central nursing station or phlebotomy center. Handheld devices with label printers are available that can download orders from the LIS and subsequently scan a patient’s identification wristband to generate LIS specimen labels at the point of care. An advantage of near-patient labeling is that the collection date and time can be automatically captured by the system and transmitted to the LIS. Once samples have been labeled with LIS bar-coded labels, the specimens only need to be scanned as “received” when they arrive in the laboratory, and are then able to be directly loaded onto automated systems for processing and analysis. In some laboratory automation systems, the specimen receipt process can occur automatically on the pre-analytic module of the automated equipment, further streamlining the process. By eliminating manual steps and leveraging the logic and routing capabilities of the LIS, order communication can reduce the risk of mislabeled specimens, incorrect container types, lost requisitions, and incorrect testing.


CPOE systems may also interface with a variety of clinical information systems (CIS), The CIS is a general term for systems that may alternatively be known as Health or Hospital Information Systems (HIS) or the electronic health record (EHR). The above systems are in general the Clinical Data Repository (CDR) that consists of the databases and systems that store patient electronic health records, including electronic reports and results from laboratory, imaging, pathology, and other diagnostic services.
Interfaces to CPOE from the CDR are essential in order to provide advanced clinical decision support during the order entry process. Interfacing can permit CPOE systems to display relevant clinical information to the ordering provider at the time of order entry. The CDR information link is essential for the implementation of certain decision support functions.


A principal benefit of CPOE is that it provides a platform to streamline workflow, standardize laboratory test ordering, promote adherence to guidelines, and deliver decision support alerts. The impact of laboratory CPOE has been assessed by numerous measures including turnaround time, error avoidance, and resource utilization.
The CPOE may be responsible for the below reported improvements.
· Reduced test turnaround time
· Decreased transcription errors
· Reduced nursing manual steps (paper requisition, transcriptions)
· Reduced laboratory manual steps (requisition handling, accessioning)
· Elimination of preprinted requisitions
· Reduced ambiguous orders and missed tests
· Reduced redundant test orders
· Improved test utilization
· Improved compliance with laboratory testing guidelines
· Improve ability to create and modify clinical templates



Clinical Decision Support Systems (CDSS)

Many of the features and advantages of CPOE systems described thus far involve providing general test information or testing advice to guide clinicians toward improved ordering practices. However, these systems do not provide patient-specific advice. While the literature varies in its use of the term “clinical decision support system” (CDSS), it generally includes those systems that integrate multiple electronic patient data sources to offer clinicians patient-specific diagnostic testing or treatment advice. To provide patient-specific testing advice, the laboratory CPOE system must have real-time, electronic access to patient data, which may include test results and medications. This is accomplished via an interface between the CPOE system and the clinical data repository. CPOE systems with CDSS typically interact with users via alert messages that are triggered by various rules as described below.

CDSS alerts cdss - Orders for Clinical Laboratory - CPOE

Alert messages are a common method that CPOE systems use to interact with users and typically consist of “pop-up” boxes displayed to clinicians at the time of order entry. Alert messages can be classified as interruptive or non-interruptive. Non-interruptive alerts simply provide information to ordering providers, but do not require specific action or halt the provider’s workflow. In contrast, interruptive alerts stop the workflow until the advice provided by the alert is either overridden or accepted. Overriding interruptive alerts may require the clinician to enter a reason for the override into the medical record.
While non-interruptive alerts may be less effective in influencing orders, interruptive alerts consume clinician time and must be used sparingly. One strategy is to reserve interruptive alerts for only the most critical issues and use non-interruptive alerts for less serious concerns. Designers of CPOE systems must also be cognizant of the concept of “alert fatigue”. Alert fatigue can occur when providers encounter alerts, particularly irrelevant ones, frequently, and begin to ignore them. Use of increasingly sophisticated support systems that provide more patient-specific alerts may reduce unnecessary or irrelevant alerts and help combat alert fatigue.

Redundant test cancellation

While there is no standard definition for a “redundant test,” it often is used to refer to the proportion of test requests that are cancelled by clinicians when they are made aware of prior results for the test. It has been estimated that eliminating redundant laboratory tests could save US hospitals more than 5 billion dollars per year. CPOE systems can alert a provider when a particular test has already been ordered or recently resulted, allowing the provider to cancel the duplicate request before it is ordered. For example, a clinician may decide that their Complete Blood Count (CBC) request is unnecessary after being presented with multiple CBC results from prior days. In addition, CPOE systems can display other relevant laboratory values. For example, the system might display a patient’s prior normal CBC results to a provider considering iron deficiency studies, as a patient with normal CBC parameters would be unlikely to benefit from an evaluation for iron deficiency.
A randomized controlled study at a primary care outpatient practice demonstrated a significant reduction in tests ordered and charges per visit when prior laboratory results were displayed on the ordering screen. Bates et al., investigated a CPOE function that alerted clinicians to potentially redundant test orders and allowed them to voluntarily cancel redundant orders or override the alerts. In response to the redundant test alerts, providers canceled the test in question 69% of the time. Similarly, Chen et al., demonstrated a 19.5% decrease in antiepileptic monitoring tests following implementation of a CPOE function that alerted clinicians to redundant tests and provided ordering guidelines.

Corollary order alerts

Not infrequently, placing one order requires clinicians to place another order. Orders that are necessitated by other orders are called corollary or consequent orders. An example of a corollary order would be a laboratory order for peak and trough gentamicin levels when ordering the antibiotic gentamicin. CPOE systems can display alerts to remind clinicians to place the corollary order. One example of corollary order alerts and their impact was reported by Overhage et al. The system suggested laboratory tests based on ordered medications and permitted the clinician to accept, modify or reject corollary orders such as partial thromboplastin time and platelets when ordering heparin, glucose when ordering insulin, and creatinine and antibiotic levels when ordering aminoglycoside antibiotics. The percentage of appropriate corollary orders was significantly higher in the intervention group receiving alert messages as compared to the control group. Further, pharmacists had to intervene less frequently for orders written by intervention group clinicians.

Expert systems and CPOE

The potential of advanced clinical decision support systems for laboratory testing has been shown by the ability of expert systems to improve the diagnostic approach in controlled settings. Smith and McNeely described a “Laboratory Advisory System (LAS),” an interactive expert system that provided patient-specific assistance in test selection. Clinicians entered a clinical problem list and the LAS then asked focused questions to obtain additional clinical information about each problem and recommend tests. Clinicians were able to accept or reject each recommendation. The LAS, when used by six physicians in a simulation of a general, private practice setting, reduced testing cost, time to diagnosis, and promoted closer adherence to established testing guidelines.

Knowledge Management

When efficiently presented and in the proper context, information about a given test may have a strong influence on whether the test is ordered. Information relevant to a test ordering decision would include test indications, guidelines, turnaround time, cost, and alternatives. Thus, for every test that may be ordered there is a collection of data that needs to be maintained about that test. Laboratory Information System (LIS) dictionaries contain information about each test including a unique ordering code, reference ranges and collection information. However, many of the fields important in clinical decision-making, including turnaround time, indications, guidelines for use, cost, and alternatives, are either not present in the LIS or not easily accessible.
With the continued progress towards electronic interfacing of provider order entry systems with the LIS, there is a growing need for order entry applications to be in synchrony with the LIS. Such synchronization can be difficult since the group responsible for CPOE is often outside the domain of Pathology and has numerous other priorities and limited resources. The development of a knowledge management system that serves as a repository of laboratory testing information may offer a solution to the aforementioned challenges. Knowledge management may be broadly defined as the process through which organizations generate value from their intellectual and knowledge-based assets. A knowledge management system for laboratory information can catalog laboratory staff knowledge and serve as a permanent bank of knowledge that remains even as individual staff members change roles or move to other facilities. In addition to CPOE, numerous other clinical applications utilize laboratory data and may benefit from having a laboratory information repository. For example, an online laboratory handbook may be generated from the same knowledge management system used for CPOE.

Studies about CPOE benefits

Several studies have reported laboratory test turnaround time improvements with CPOE. For example, Thompson et al., found that following the implementation of CPOE in the intensive care unit of a teaching hospital, the average time from ordering to resulting of stat laboratory tests decreased from a median of 148 min to 74 min. In addition to improving laboratory turnaround time, CPOE systems have been demonstrated to improve the overall utilization of laboratory resources.
Following CPOE implementation at a UK hospital, Nightingale et al., not only found a decrease in total laboratory test volume and laboratory costs, but also an increase in the appropriate ordering of ten tests judged to have been previously underutilized. This study offered evidence that the CPOE system did not simply reduce across the board test ordering, but rather improved the overall appropriateness of test orders. Further, improvements in laboratory utilization may translate into hospital-wide savings.
Hwang et al., evaluated the impact of a CPOE system that included both medication and laboratory orders and demonstrated that patients were receiving fewer STAT laboratory tests and had shorter hospital stays following implementation of CPOE. In each of these examples, the implemented CPOE system had numerous attributes that may have been contributory to utilization and efficiency improvements.


CPOE systems offer the clinical laboratory a powerful tool to promote appropriate laboratory test selection and enhance the accuracy and efficiency of the entire laboratory testing process. Potential CPOE benefits include improved test utilization, reduced costs, fewer errors, and better adherence to practice guidelines. Numerous strategies have been employed within the context of CPOE systems to improve workflows and ordering practices. One of the key determinants of the utility and functionality of a given laboratory CPOE system is the ability of the system to interact with LIS and other portions of the electronic health record. Given the variability of systems and implementations, laboratory directors must carefully plan CPOE implementations to ensure that the system will meet the institution’s goals and be compatible with its workflows.