Just the Facts: Role of Evidence-Based Medicine in Clinical Microbiology

Dec. 3, 2018

Early in my career, I switched from internal medicine to clinical microbiology. One thing that took me by surprise as part of this switch in 2002—the lack of evidence-based clinical guidelines in clinical microbiology, which had previously been a part of my day-to-day decision making process.

I often tell microbiology trainees the story of how, while I was a student rotating through the different medical specialties, anesthesiologists would cite recent guidelines from the Society of Cardiovascular Anesthesiologists for management of cardiopulmonary bypass, and how gastroenterologists adapted their practices to follow the most recent American College of Gastroenterology guidance for patients with acute lower gastrointestinal bleeding. Just about every medical specialty cited their own organization’s guidelines (and still do!). As students and residents, we reviewed these guidances during journal club and rounds.  

During my training in clinical microbiology, I learned approaches and adapted practices from mentors, textbooks and journal publications. It wasn’t until I started teaching microbiology as a fellow and, later, as one of the directors of a clinical microbiology laboratory, that I recognized the lack of evidence-based guidelines in this field. For instance, microbiology trainees would ask me why I rejected a repeat Clostridioides difficile stool order a few days after a previous negative. Similarly, the clinical service would sometimes ask us for guidelines citing the strength of the evidence behind my rejection of a specimen or sample. I would cite a published paper and a textbook or 2, but these sources sometimes seemed insufficient to our evidence-driven clinical colleagues.

We were being asked to show our clinical colleagues the data backing up our decisions, and speak to the strength of those data. Granted, we had a variety of other sources at our fingertips, but there was a paucity of evidence-based guidelines compiled and written by microbiologists. We had microbiology Cumitechs (Cumulative Techniques and Procedures in Clinical Microbiology) which were consensus recommendations covering a variety of subjects and based on key leader opinions. Cumitechs were transitioned around 2013 to Practical Guidance for Clinical Microbiology [PGCM] documents which are now published in the journal Clinical Microbiology Reviews. Other professional societies such as the Infectious Diseases Society of America (IDSA) incorporated laboratory medicine practices in their practice guidelines and cited the evidence for their recommendations, but involvement of microbiologists on these panels was not invariably achieved at the time. Although the data we presented to our clinical colleagues back then may have been in a peer-reviewed publication, or published by key opinion leaders, there was often no systematic process by which those data had been vetted or synthesized.

Formal Practice Guidelines for Microbiologists

Clinical practice guidelines provide recommendations that are supported by evidence. The evidence is systematically reviewed by qualified professionals using various approved methodologies. This systematic review makes the conclusions of such reviews robust.

Medical specialty organizations have a long history of establishing clinical practice guidelines. The Guidelines International Network is a global library repository of guidelines from around the world. In the United States, the National Guideline Clearinghouse (NGC), run by the Agency for Healthcare Research and Quality (AHRQ), has provided health care professionals with clinical guidelines covering many medical specialties free of charge for the past 20 years.

However, medical microbiology has lagged behind other medical specialties in compiling evidence-based guidelines. In response to this lack of guidance, ASM formed the Evidence-Based Laboratory Medicine Practice Guidelines (EBLMPG) committee in 2011. The purpose of this group is to support development of evidence-based guidelines by compiling topics and recruiting authors, while ensuring that these guidelines are developed in a transparent, objective and rigorous manner. The EBLMPG group adapted the Centers for Disease Control and Prevention’s (CDC) A-6 methodology to evaluate scientific evidence. After formulating the initial question, the PICO strategy of assessing “population,” “intervention,” “comparator or reference test” and “outcome” is applied. Subsequently, the A-6 cycle may be covered by the following steps:
  1.  Ask the question.
  2. Acquire the evidence.
  3. Appraise individual studies for inclusion.
  4. Analyze the evidence.
  5. Apply the recommendation.
  6. Assess the impact.
Several systematic Laboratory Medicine Best Practices (LMBP) reviews have been published, and a few have been related to clinical microbiology. Notably, Snyder SR et al. published in 2012 on effectiveness of 3 blood collection practices aimed towards reducing blood culture contamination rates. In 2016, two EBLMPG documents were published in Clinical Microbiology Reviews. One ASM/CDC publication assesses the effectiveness of various practices to increase timely therapy for patients with bloodstream infections. Another ASM/CDC publication addresses the effectiveness of preanalytic practices on contamination and accuracy of urine cultures. Other EBLMPG publications by these groups are in progress.

Assessing the Guidelines

The LMBP process ensures that decisions are based upon evidence that is well vetted. The Standards for Reporting of Diagnostic Accuracy Studies (STARD) initiative has recently been updated to encourage robustness of data inclusion and reporting when developing evidence-based guidelines. Another tool used to evaluate the effectiveness of such guidelines is the Appraisal of Guidelines for Research Evaluation II (AGREE II), funded by the Canadian Institutes of Health Research. The AGREE II instrument has proven useful for evaluating strengths and weaknesses of current guidelines and to direct the design of future investigations. The AGREE II tool was recently used to assess 4 sets of clinical practice guidelines concerning clinical microbiology. Authors concluded that the guidelines performed poorly in the domain of stakeholder involvement (i.e., views and preferences of the targeted users of the document were not adequately sought). Stakeholder involvement in compiling guidelines is important when considering the outcomes and aspects of the illness, as well as to ensure that the final guideline is understood by the affected group. The authors of the paper also stated that the guidelines did not adequately define the target user population. Finally, authors emphasized the importance of assessing overlap between different organizations’ guidelines to avoid disseminating conflicting guidance. Appropriate stakeholders must be involved in development of guidelines that directly affect them. Thus, laboratory guideline groups or committees should include laboratorians as well as groups which are essential in carrying out such guidelines, such as nurses and physicians. These assessments are useful in designing future studies and developing future guidelines.

ECRI Replaces National Guideline Clearinghouse

The movement towards evidence-based guidelines comes at a difficult time in light of the recent government shutdown of the National Guideline Clearinghouse (NGC) guidelines website, which went dark on July 16, 2018. Vetted records of over 14,000 guidelines subsequently became unavailable. Federal cutbacks in spending were blamed for the closing.

Luckily, an independent nonprofit patient safety and health care research organization, the ECRI Institute, has taken over the job of vetting and scoring medical guidelines. ECRI was the sole prime contractor for the NGC site, so their past experience made them a logical next choice to continue this service. On November 19, 2018, the ECRI Guidelines Trust™ portal was launched to fill the void in publicly accessible, web-based clinical guidelines. The Trust’s purpose is to provide new summaries of evidence-based guidelines.

Guidelines on the new ECRI Guidelines portal are searchable by medical specialty (e.g., infectious diseases, but not clinical microbiology, is a specialty on this site) and by the organization that published the guidelines (the 2 ASM LMBP assessments published in 2016 in Clinical Microbiology Reviews are included on the ECRI site). I found the site very easy to navigate. The Transparency and Rigor Using Standards of Trustworthiness (TRUST) scorecards provide easy visual ratings for how well guidelines performed in various areas of Institute of Medicine’s standards for trustworthiness of guidelines.

Evidence-based guidelines are important not only to guide our practice but also to support our decisions when we communicate them to clinical colleagues. ASM is now formally represented on applicable IDSA guidance documents when they pertain to the laboratory, and other opportunities to support microbiology representation on evidence-based guidelines are actively pursued. The practice of clinical microbiology is changing to one that is more evidence-based, which we hope will lead to more efficient communication with our colleagues and better patient care.

Author: Audrey Schuetz

Audrey Schuetz
Audrey Schuetz is Associate Professor of Laboratory Medicine and Pathology at Mayo Clinic College of Medicine and Science in Rochester, Minnesota.