Diagnostic Stewardship as a Model To Improve the Quality and Safety of Diagnosis

Diagnostic stewardship refers to a range of actions to promote optimal use of diagnostic tests, improve the speed and accuracy of diagnosis, and reduce the occurrence of misdiagnosis due to false positive or false negative findings. The benefits of diagnostic stewardship include improved efficiency and more appropriate use of healthcare resources. Here, however, we focus on how diagnostic stewardship reduces the risk of diagnostic errors and patient harm. 

Preanalytic interventions

Most diagnostic stewardship interventions have focused on the preanalytic phase of the testing process by supporting appropriate selection and ordering of diagnostic tests.^10,35 On one end of the spectrum are interventions such as clinician education, algorithms that include indications for test use, and modifications to health information technology (IT) systems. These modifications may include reminders, alerts, hard-stops, and changes to default computerized order entry (CPOE) interfaces to encourage appropriate use of testing. 

For instance, an initiative at Massachusetts General Hospital, co-led by representatives from pathology and internal medicine services, aimed to encourage more “hypothesis-driven” use of testing and reduce use of unnecessary daily laboratory tests for inpatients. After the hospital implemented a combination of interventions, including emails to clinicians and modifications to the CPOE system and order sets, daily inpatient laboratory order volume decreased 60 percent, even as overall routine laboratory order volume remained stable.³⁶ Although it is plausible that fewer unnecessary tests translated to reductions in false positive diagnoses, the authors of the study could not measure these outcomes. 

On the more labor-intensive end of the spectrum are interventions to encourage appropriate use of testing, such as real-time laboratory consultation on test selection (see “Diagnostic management teams” below) and mandatory review of certain orders by laboratory personnel before a test is performed. For instance, one study indicated that review of genetic test orders by genetic counselors in a national reference laboratory resulted in cost savings of $48,000 per month from cancellation of inappropriate tests.³⁷

Increasing the use of appropriate diagnostic testing practices requires coordinated interventions to change clinician culture and ordering behavior to combat both over- and underuse. Failure to assess for and monitor chronic kidney disease (CKD), particularly in people with diabetes, is an example of underuse of testing that can result in delayed diagnosis and preventable disease progression.³⁸ An Indian Health Service (IHS) initiative in 2003 to improve diabetes care included implementation of routine glomerular filtration rate reporting. An intervention in 2006 involved annual albumin-creatinine ratio reporting in patients with diabetes. 

These changes, combined with education and other components of the IHS’s population-based kidney care program, are believed to have contributed to the 54 percent reduction in the incidence of diabetes-related end-stage renal disease in the American Indian/Alaska Native population between 1996 and 2013.³⁹ Similar initiatives in the Veterans Health Administration⁴⁰ and managed care settings⁴¹ have aimed to standardize the use of laboratory tests for CKD screening and monitoring in high-risk patients.

Finally, improving specimen collection practices can further reduce false positive diagnoses and is an essential component of stewardship efforts where specimen contamination is a known problem. For blood cultures, several strategies have been shown to reduce contamination rates: education of clinical staff, reinforcement of appropriate collection techniques, and use of diversion devices that eliminate the first 1-2 mL of a blood draw to remove skin fragments colonized by bacteria.^42,43

Analytic interventions

Analytic interventions focus on laboratory actions and include internal quality control procedures (e.g., contamination prevention), as well as actions to promote diagnostic accuracy and efficiency. Reflex testing refers to further testing that is performed automatically (i.e., according to algorithm) when certain criteria are met. For example, reflex testing for biomarkers in some newly diagnosed cancers can further characterize a malignancy and expedite treatment selection compared with the traditional pathway of sequential testing mediated only through the treating oncologist.^44-47

Distinct from reflex testing, reflective testing is more commonly described in the United Kingdom and Europe. It refers to an expanded decision-making role of the laboratory professional, such that the decision to perform further testing may be mediated by professional judgment rather than by a prespecified protocol or algorithm.^48,49

A randomized trial in the Netherlands compared reflective testing with a control condition. In reflective testing, laboratory professionals were allowed to add tests they believed were indicated to the tests general practitioners ordered. In the control condition, practitioners received only the test results they personally ordered. The subsequent management of patients was more likely to be rated by an independent record reviewer as “adequate” (versus neutral or not adequate) in the reflective testing condition.⁵⁰ However, it is unclear to what extent observed improvements in management were attributable to improvements in diagnosis.

Postanalytic interventions

Interventions to improve the postanalytic testing phase aim to facilitate interpretation of test results and encourage appropriate followup actions. Postanalytic interventions often focus on modifying the text of test result reports. These modifications, which in many scenarios can be delivered through clinical decision support systems or templated language in laboratory reports, have been shown to significantly influence prescribing decisions, including de-escalation of unnecessary treatments. 

Examples from infectious disease testing include:

• Using language that definitively rules out specific infections.^51,52
• Normalizing colonization of organisms in the absence of symptoms (e.g., candiduria⁵³).
• Selectively reporting preferred antibiotic susceptibilities to encourage guideline-concordant prescribing.⁵⁴ 

Laboratory assistance in interpreting test orders can also be leveraged in scenarios where interpretation is more complex. In a study at a single facility, pathologist-generated interpretive narratives for coagulation test panels were reported to reduce time to diagnosis for nearly half of ordering physicians.⁵⁵ 

Problems with tracking, followup, and interpretation of completed test result reports contribute to diagnostic error. Diagnostic stewardship has addressed this issue in limited examples but not within the broad scope of diagnostic testing overall.^56-59 For example, antimicrobial stewardship teams have been involved in interpreting and communicating test results for rapid microbiology testing from blood samples⁶⁰ or serial C. difficile testing.⁶¹ These practices suggest the benefit of more thoughtful test reporting and interpretation using diagnostic stewardship. 

Effectiveness of diagnostic stewardship interventions

A meta-analysis by Rubinstein, et al., examined the strength of the evidence supporting seven specific practices, as well as “combined practices,” to promote appropriate (e.g., guideline-concordant, nonduplicative) use of diagnostic laboratory tests.³⁵ The authors found evidence that two standalone interventions, modification of CPOE (e.g., limiting test availability in the user interface, alerting clinicians to redundant test orders) and reflex testing, each increased appropriate use of testing. 

Evidence was insufficient to make recommendations for or against other specific standalone interventions such as education, feedback, or test review. However, evidence supported “combined” practices, most of which included a clinician education and feedback component. Although these interventions increased appropriate test use, little evidence is available thus far to assess their impact on diagnostic errors.

Diagnostic stewardship has largely been evaluated in relation to infections. Large quality improvement efforts focused on diagnostic stewardship have observed a 30-60 percent reduction in C. difficile bloodstream infections and catheter-associated urinary tract infections and associated antibiotic use with these practices.^14,62-65 Diagnostic stewardship of rapid blood cultures improved time to appropriate antibiotic use.⁶⁰

Regardless of target, effective diagnostic stewardship interventions not only shape behavior but also educate clinicians on appropriate use of testing.¹⁴ The design of these interventions must also take into consideration the potential for unintended consequences such as increased clinician workload. Development should involve laboratory professionals, clinician end users, patients,⁶⁶ and ideally, informatics and human factors experts as well.¹¹

A survey of 78 clinicians in 9 European countries suggested that diagnostic stewardship interventions were acceptable to most clinicians,⁶⁷ although other data suggest that clinicians prefer interventions that preserve their autonomy.^68,69 Designing diagnostic stewardship inteventions with the input of clinician end users has improved clinician satisfaction.⁷⁰ Balancing the needs and goals of various stakeholders is critical to buy-in and successful implementation.