Inappropriate laboratory test selection in the form of overutilization as well as underutilization frequently occurs despite available guidelines. There is broad approval among laboratory specialists as well as clinicians that demand management strategies are useful tools to avoid this issue. Most of these tools, which may be adopted to local settings, are based on automated algorithms or other types of machine learning. We believe that artificial intelligence may help to further improve these available tools.
DM tools may help to prevent overutilization and/or underutilization. Many studies combine several tools , which has been shown to have an additive effect on the overall outcome . In addition, the collaboration of laboratory specialists and clinicians together with audits, feedbacks, reminders and multiple plan-do-study-act (PDSA) cycles will further improve efficiency in terms of a continuous improvement process .
Alerts appearing in the form of pop-up windows in the clinical physician order entry (CPOE) system may be designed to avoid various causes of overutilization  or to suggest an alternative test . Minimum retesting intervals (MRIs), which may also be implemented in form of alerts at the stage of order entry, are discussed in section 2.3.
Informing the ordering provider through alerts at the stage of order entry would be the preferred solution; however, it may not always be possible to reject inappropriate orders in the CPOE system due to technical issues. In these cases, orders may be screened for appropriateness upon arrival in the LIS . MRIs, which may also be considered as a subset of holding back orders, are discussed in the following section.
MRIs are defined as “the minimum time before a test should be repeated, based on the properties of the test and the clinical situation in which it is used” . Recommendations for MRIs are freely available, for example, from the collaboration of the Royal College of Pathologists, the Association for Clinical Biochemistry and Laboratory Medicine and the Institute of Biomedical Science . MRIs may be implemented in the LIS, dependent on available technical possibilities . One drawback of rejecting tests in the LIS is that unnecessary blood collections may be performed for cancelled tests. Therefore, it would be favorable if the requesting physician is at least alerted in the course of order entry . Preferably the ordering physician is alerted at the stage of order entry along with the choice to cancel the request or to continue with the order .
The position where tests are placed in the order entry system may affect the number of placed orders . Furthermore, laboratory ordering profiles (LOPs), which are used to order a bundle of defined analytes with one click in the CPOE system, seem to be a source of overutilization; number of orders drops after removing tests from such LOPs . One study describes the implementation of a panel for C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) testing , while others focus on LOPs for specific indications or diagnoses .
Apart from giving an alert for inappropriate orders, tests may also be entirely removed from the order entry system .
Some studies evaluated the effect of displaying costs during the order entry process. Overall, the interventional impact was rated as “modest” by the authors . Investigation of appropriateness of test selection was not part of the study designs. However, costs should never be the sole decision criterion for laboratory test ordering, reductions in expenditure may be also achieved by implementing DM strategies, which combat overutilization .
Adding tests may be one attempt to prevent delayed or missed diagnoses .
Another possibility of adding tests is through reflex or reflective testing. While reflex testing refers to the automated addition of tests according to a fixed algorithm within the LIS, reflective testing is the approach of adding tests and/or comments after the laboratory specialist has interpreted the results in synopsis with available clinical information . For example, reflex testing may be suitable for the stepwise analysis of thyroid hormones, where thyroid-stimulating hormone (TSH) is the initial test, and subsequent analysis of free thyroid hormones should only be performed in the case of abnormal TSH results . Reflex as well as reflective approaches may also be combined .
Algorithms are an advancement of reflex und reflective testing; several concatenated if/then queries are addressed, until a diagnostic decision is possible . One practical example of such an algorithm is the PTT Advisor, a mobile application that helps to choose the appropriate follow-up tests in patients with a prolonged partial thromboplastin time (PTT) and normal prothrombin time . However, an evaluation of apps with regard to the impact on test ordering would be meaningful . Another way to implement diagnostic algorithms would be to program the according if/then cycles directly into the LIS .
Educational interventions may be implemented in different ways. As sole method in the form of a workshop , as the first step of a two-stage process  or supplementary to IT-based solutions . However, education as a sole method seems to be inferior compared to automated solutions . IT-based solutions may also serve as a learning tool , although this could not be confirmed by others .