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The value of diagnostics : From orientation to disease management
Improving access to diagnostic testing at time of prescribing enables clinicians to make more informed empirical prescribing decisions , reduce unnecessary antimicrobial use and minimise the burden of antimicrobial resistance .
Stephen Hughes MPharm MSc MBA Chelsea and Westminster Hospital NHS Foundation Trust , UK
The modern-day hospital laboratory provides a wide range of services including clinical chemistry , microbiology , haematology , histopathology and molecular biology , each of which is designed to support physicians in making a clinical diagnosis . Moreover , in 2019 , the World Health Organization ( WHO ) outlined a list of essential in vitro diagnostics ( IVDs ), 1 which they defined as : “ devices which , whether used alone or in combination , are intended by the manufacturer for the in vitro examination of specimens derived from the human body solely or principally to provide information for diagnosis or monitoring for compatibility purposes .”
The WHO list encompasses the minimum set of IVDs that should be available in both primary and secondary care settings to ensure good quality and appropriate healthcare worldwide . The importance of laboratory diagnostic testing should not be underestimated and , as noted by Lippi and Plebani , “ it is now undeniable that laboratory medicine provides a kind of information that increasingly supports ( and occasionally replaces ) the clinical judgment .” 2 Some insight into the value of laboratory diagnostic tests in practice comes from a study of over 72,000 patient encounters in a hospital setting . The analysis revealed that laboratory tests were the most frequent diagnostic procedure , ordered for 35 % ( 25,334 / 72,197 ) of patients , with 56 % of emergency department ( ED ) patients having at least one laboratory test ordered . 3
Diagnostic biomarkers that detect or confirm the presence of a particular disease are increasingly incorporated in IVDs to support clinical decision making in many therapeutic areas to optimise the care of hospital patients .
Value and place of diagnostics along the patient pathway Diagnostic testing is an essential component in diagnosing and monitoring disease , measuring treatment response and measuring population level disease activity . These tests are primarily analysed in the laboratory setting , benefiting from this centralised approach to obtain scale of economy , improve quality assurance or availing of larger or more complex technology systems .
Point-of-care tests ( POCT ), performed at the patient bedside for timeliness and convenience , are an important part of the diagnostic pathway but the available testing is limited . Testing , both lab-based or POCT , can be further classified by its purpose within healthcare ( Table 1 ). 1
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TABLE 1
Summary of tests available
Tests available Screening Diagnostics
Monitoring tests
Prognosis
Staging
Definition To detect a disease / condition in asymptomatic individuals
To confirm a patient ’ s disease or condition ; rule out or confirm diagnosis in select population
To monitor the patient ’ s progress or response to treatment or to monitor the treatment itself
To predict a person ’ s likelihood of developing a disease / condition or experiencing a defined medical event
To categorise patients with confirmed disease into clinically relevant groups for choice of therapy , predicting outcomes , response to therapy or for other medical reasons