Clinicians and laboratory professionals can improve patient outcomes and reduce unnecessary treatment by implementing structured diagnostic stewardship programs, Kaede Ota Sullivan, MD, MSc, MBA, said Friday at the Association for Molecular Pathology (AMP) 2025 annual meeting in Boston. In a presentation on optimizing diagnostic stewardship, she provided a clinician’s perspective on effective test utilization, emphasizing the need to modify ordering, testing, and reporting processes to ensure that tests are used appropriately.

Dr. Sullivan, an infectious disease specialist and medical microbiologist at the Lewis Katz School of Medicine at Temple University in Philadelphia, illustrated this principle with data from Clostridium difficile testing, noting that chart reviews at Johns Hopkins Hospital found that roughly 42% of reported hospital-onset C. difficile infection cases did not meet clinical criteria, with inappropriate testing and treatment occurring in many instances.¹

“Sometimes the best outcome for a patient is no treatment at all,” Dr. Sullivan said. “Overdiagnosis and overtreatment not only increase health care costs but can also harm patients.”

To reduce inappropriate C. difficile test orders and unnecessary treatment, Dr. Sullivan explained how diagnostic stewardship can be applied across the entire testing process. This approach involves modifying how tests are ordered, performed, and reported to optimize diagnosis and treatment. In practice, laboratories can guide providers through institutional guidelines, clinical pathways, and algorithms, often implemented through clinical decision support systems integrated into electronic health records.² She explained how measures such as soft or hard stops that alert clinicians when a test might be inappropriate, as well as preferential test selection and removal of less useful tests from order sets, can help ensure appropriate ordering.

Optimizing specimen collection, test performance, and reporting is equally important, including selective reporting or adding interpretive comments to assist clinicians, said Dr. Sullivan. The goal is to achieve accurate diagnoses and appropriate treatment while avoiding patient harm, improving care efficiency, controlling institutional costs, and maintaining quality metrics.

Dr. Sullivan also stressed the importance of optimizing laboratory processes. She cited a multicenter study from the Duke Convalescent Network that implemented reflex toxin testing for polymerase chain reaction (PCR)–positive C. difficile samples. This approach decreased reported infection rates from 7.05 to 2.28 cases per 10,000 patient days and cut antibiotic therapy by nearly half without increasing adverse outcomes.³

She also discussed strategies for syndromic panels, including gastrointestinal, meningitis/encephalitis, and pneumonia panels. These approaches involve restricting testing to patients with high pretest probability, confirming rare positive results, and providing integrated reporting with interpretive comments to guide clinicians.^4,5

“You want to select patients with high pretest probability,” she said. “Even excellent tests can give misleading results if applied indiscriminately.”

Dr. Sullivan outlined the multidisciplinary nature of diagnostic stewardship programs. Success relies on collaboration among laboratory personnel, infectious disease specialists, medical staff, nursing, and information technology teams. She advised involving leadership early to support policy implementation and education initiatives.

Finally, Dr. Sullivan recommended resources for further guidance, including a publication by the SHEA Diagnostic Stewardship Task Force, ⁶ which “provides practical examples of how to optimize test ordering, processing, and reporting to ensure the best outcomes for patients and health care systems.”

References

1. Rock C, Pana Z, Leekha S, et al. National Healthcare Safety Network laboratory-identified Clostridium difficile event reporting: a need for diagnostic stewardship. Am J Infect Control. 2018;46(4):456-458. doi:10.1016/j.ajic.2017.10.011

2. Mizusawa M, Small BA, Hsu YJ, et al. Prescriber behavior in Clostridioides difficile testing: a 3-hospital diagnostic stewardship intervention. Clin Infect Dis. 2019;69(11):2019-2021. doi:10.1093/cid/ciz295

3. Turner NA, Krishnan J, Nelson A, et al. Assessing the impact of 2-step Clostridioides difficile testing at the healthcare facility level. Clin Infect Dis. 2023;77(7):1043-1049. doi:10.1093/cid/ciad334

4. Hitchcock MM, Gomez CA, Pozdol J, Banaei N. Effective approaches to diagnostic stewardship of syndromic molecular panels. J Appl Lab Med. 2024;9(1):104-115. doi:10.1093/jalm/jfad063

5. Dien Bard J, McElvania E. Panels and syndromic testing in clinical microbiology. Clin Lab Med. 2020;40(4):393-420. doi:10.1016/j.cll.2020.08.001

6. Fabre V, Davis A, Diekema DJ, et al. Principles of diagnostic stewardship: a practical guide from the Society for Healthcare Epidemiology of America Diagnostic Stewardship Task Force. Infect Control Hosp Epidemiol. 2023;44(2):178-185. doi:10.1017/ice.2023.5