Medical decision-support systems are designed to assist health professionals with clinical decision making in the normal course of their duties. Despite their name, clinical decision-support systems are able to offer help in no clinical areas like administration and cost control as well as in patient care and population and disease management. In the summer 1999 issue of the Journal of Healthcare Information Management, published by the Healthcare Information and Management Systems Society (HIMSS), Leslie Perreault and Jane Metzger cite these key clinical decision-support systems functions:

1. Administrative: Supporting clinical coding and documentation, authorization of procedures, and referrals;
2. Managing clinical complexity and details: Keeping patients on research and chemotherapy protocols; tracking orders, referrals follow-up, and preventive care;
3. Cost control: Monitoring medication orders and avoiding duplicate or unnecessary tests; and
4. Decision support: Supporting clinical diagnosis and treatment-plan processes; and promoting use of best practices, condition-specific guidelines, and population-based management.

So these systems can be applied to many different types of clinical tasks. Some of these tasks include:

1. Assist in Faster Decision Making: Most practitioners use computing systems, either directly or indirectly, to gather laboratory results, radiology reports, or the narrative text of notes or consultations. This is because laboratories and transcription services have long used computing systems to report these data. Reporting of results and the creation of a customized report or graph can make patterns more apparent, leading to faster diagnosis. This is one of the simplest forms of decision support, and it is highly popular with clinicians because it does not require data entry and saves time.
2. Provide Reminders and Prompts: One of the most powerful tools in the field of medical decision-support systems is the capability to generate reminders and prompts to clinicians. As several reviews have shown, reminders change clinician behavior to improve delivery of chronic, acute, and preventive medical care. Reminders can be brought to the attention of clinicians in a variety of ways: printed sheets can be affixed to a chart before a visit, windows can appear on a screen, or a list of reminders can appear on an electronic cover sheet. Usually, reminders include a short message recommending some action be taken along with the rationale for the reminder appearing on that particular patient. Methods of creating, editing, and using rules to trigger reminders vary greatly among clinical decision-support systems.
3. Assist in Order Entry: Among the most successful uses of medical decision-support systems is to check orders directly entered by a clinician in real time. Feedback to the clinician through screen dialog boxes can alert the clinician to drug sensitivity, drug allergy, drug-drug, drug-disease, and drug-laboratory interactions, and potential duplication of services. Orders that should be considered when one order is placed (‘corollary’ orders, such as blood levels when an amino-glycoside is prescribed) are much more likely to be ordered when presented at the time of order entry. If order-entry screens are designed to display the results of previously ordered tests of the type being ordered, test ordering has been shown to be reduced by 13%. Applications to allow direct entry of medication orders are among the most difficult clinical computing applications to develop, yet they have been demonstrated to dramatically reduce serious medication errors.
4. Assist in Diagnosis: An early goal of decision-support systems used in clinical care was to help the physician establish a diagnosis. Programs such as Internist-1, QMR, DXplain and ILIAD were designed to consider historical and physical examination findings, laboratory and test results, and create a list of diagnoses to explain those find. These systems were based on large collection of rules and tables that related the presence or absence of findings with diseases and other conditions. Though they performed remarkably well, the requirement that large amounts of data be entered limited their broad use in clinical care. Freestanding applications are now less common than applications that are tightly integrated with patient data in a repository or computer-based medical record systems. Moreover, much of the information needed to use these applications —e.g., the presence or absence of symptoms or physical examination findings— is not routinely captured in computing systems in a form that can be processed by decision-support systems.
5. Review New Clinical Data: Reminders and order checks are useful methods for drawing clinicians’ attention to important occurrences when the clinician is viewing a computer screen or paper chart, or is in the process of ordering. However, in some cases, there is a need to bring clinical events such as a new or changed laboratory result, hospital discharge, or combination of events to the attention of the clinician at the moment the event occurs. In these cases, software ‘agents’ can be sent to search for and retrieve information, for example through the Internet or on the network, which is considered relevant to a particular problem. The agent may contain knowledge about its user’s preferences and needs, and may also need to have medical knowledge to be able to assess the importance and utility of what it finds. When an electronic message is received, a specified rule can then be run to determine if there is a need to notify the clinician or take other action.
6. Image Recognition and Interpretation: Many medical images can now be automatically interpreted, from X-rays through to more complex images like angiograms, CT and MRI scans. This is of value in mass-screenings, for example, when the system can flag potentially abnormal images for subsequent detailed human attention.
7. Cost Control: Medical decision-support systems can also be set up to focus on costs. They can simply displaying the price of a test being ordered or issuing a prompt telling a physician that the pharmacy and therapeutics committee at the health care organization he’s part of recommends an alternative medication that’s less costly and just as efficacious. They can also reduce in costs due to fewer medication errors and adverse drug events.