CHAPTER 1 Jeanne‐Marie Guise Division of Maternal‐Fetal Medicine, Departments of Obstetrics and Gynecology, Medical Informatics and Clinical Epidemiology, Public Health and Preventive Medicine, and Emergency Medicine, Oregon Health and Science University, Portland, OR, USA …decisions about the care of individual patients should be based on the conscientious, explicit, and judicious use of the current best evidence on the effectiveness of clinical services. IOM Knowing What Works in Health Care 2008 [1] While all clinicians want to use the best evidence to make health care decisions, with 37 reviews, 47 randomized control trials (RCTs), and two guidelines published every day, it is impossible for practicing clinicians to keep up with all the new evidence and decide whether it is sufficient to suggest that they should change their practice. This book provides a summary of evidence for the major clinical areas of practice within the specialty of Obstetrics and Gynecology (OB/GYN), and this chapter (i) provides an overview and context, discussing the history of evidence based medicine (EBM) in OB/GYN; (ii) describes the importance and conduct of a systematic evidence review, a hallmark of EBM and contemporary evidence‐based decision‐making; and (iii) provides additional EBM resources and references for interested readers. OB/GYN has played a long and important role in shaping what is known today as EBM, although it did not always embrace evidence. The beginnings of OB/GYNs relationship with EBM may have started in the 1800s when women went to Lying‐in Hospitals to stay for days or months in preparation for and recovery from childbirth. Lying‐in hospitals were often crowded, and rates of maternal and child death from childbed fever (puerperal sepsis) were high. Some women were said to prefer giving birth in the streets, pretending to have given birth en route to the hospital. Ignac Semmelweiss, perplexed by the lower rates of maternal mortality for women delivering outside the hospital said: “To me, it appeared logical that patients who experienced street births would become ill at least as frequently as those who delivered in the clinic…What protected those who delivered outside the clinic from these destructive unknown endemic influences?” [2]. He also observed that there were higher rates of maternal mortality from childbed fever in the First Division Hospital, which was staffed by physicians, compared with the Second which was staffed by midwives. Both units had trainees, performed examinations, and saw roughly similar populations. He realized that unlike the midwives, physicians all performed autopsies on women who died the night before prior to beginning their clinical duties on the maternity ward. In 1847, Semmelweiss figured out what might be occurring when a forensic medical professor, Jakob Kolletschka, died of sepsis after sustaining an accidental finger stick during an autopsy. He concluded that, “In Kolletschka, the specific causal factor was the cadaverous particles that were introduced into his vascular system. I was compelled to ask whether cadaverous particles had been introduced into the vascular systems of those patients whom I had seen die of this identical disease. I was forced to answer affirmatively” [2]. He required physicians wash their hands with chlorinated lime before examining patients. The mortality rate in District 1 fell from 11.4% prior to handwashing to 1.27% (rates were 2.7% and 1.33% in District 2). The medical community did not embrace this new evidence. Semmelweiss was ridiculed by physicians who were offended by the suggestion they were unclean, and his theory was rejected because it was contrary to the accepted belief that childbed fever was caused by miasmas or “bad air.” In response, Semmelweiss could only figuratively shake his head: “One would believe that the clarity of things would have made the truth apparent to everyone and that they would have behaved accordingly. Experience teaches otherwise. Most medical lecture halls continue to resound with lectures on epidemic childbed fever and with discourses against my theories” [2]. Fast forward to the 1950s and 1960s and two stories demonstrate how difficult it is for new evidence to change clinical practice even when that evidence is strong – and how profound the consequences for this failure. In the 1950s, diethylstilboestrol (DES) therapy was used to prevent miscarriage. Its use was established through uncontrolled studies. Even though randomized controlled trials were published in the mid‐1950s that found no significant prevention offered by DES, its use had become so commonplace that it continued despite the evidence. It was not until 1971 that the food and drug administration (FDA) brought national attention to the harms of DES exposure (associated with vaginal clear cell carcinoma) and banned its use in pregnancy. Total exposure to DES for mothers and daughters has been estimated to exceed 10 million worldwide. The story of antenatal corticosteroids is not only a major discovery in obstetrics but is also emblematic of the importance of EBM. In the 1960s, Graham “Mont” Liggins, an Australian obstetrician, had a sheep farmer neighbor and wondered why ewes delivered prematurely when worried by dogs [3]. Liggins suspected it may have something to do with the stress‐response in the mother and the release of cortisol. He conducted an experiment where he administered corticosteroids to pregnant ewes and found they delivered prematurely. Unexpectedly, he also found that the lambs delivered by ewes that received corticosteroids survived in far greater numbers than he would have expected given the severe degree of their prematurity [4]. In the 1970s, Liggins and a pediatrician colleague, Ross Howie, conducted the first randomized trial in humans to test their theory that corticosteroids reduced the occurrence of respiratory distress syndrome (RDS). RDS and mortality rates were significantly reduced in the treated group (6.4%) as opposed to 18% in placebo treated mothers. Within a decade of this first RCT additional studies supported the conclusion that corticosteroids significantly reduced infant mortality for prematurely born children. However it was not until the mid‐1990s that antenatal steroids became part of routine practice for women at risk of premature delivery (after a meta‐analysis was published in 1989). The forest plot from a meta‐analysis of antenatal corticosteroids represents this delay, demonstrates the potential power of systematic reviews and meta‐analyses of a body of evidence, and has become the symbol for the Cochrane Collaboration, the most recognized source for evidence‐based systematic reviews in medicine. It has been estimated that tens of thousands of babies would have been saved by earlier implementation of steroids. It is perhaps not a surprise that Archie Cochrane, for whom the Cochrane Collaboration is named awarded the field of OB/GYN the first wooden spoon award for failing to evaluate the care they provide with RCTs and failing to apply results of RCTs in practice [5]. He went further stating that GO in Gynecology and Obstetrics should stand for “go ahead without evidence” [6]. EBM, refers to a process of turning clinical problems into questions and systematically locating, appraising, and synthesizing research findings as a basis for clinical decision‐making. Gordon Guyatt [7] first used the term “EBM” in the 1980s to describe an approach to residency training at McMaster University School of Medicine where residents were taught how to identify, interpret, and use the literature in their clinical decision‐making. At first he wanted to call it “Scientific Medicine” but reconsidered when others argued that the title would imply all other medicine was non‐scientific [8]. Further refined by David Sackett, “EBM requires a bottom‐up approach that integrates the best external evidence with individual clinical expertise and patient choice” [9]. The systematic review is a hallmark of EBM. Systematic reviews apply a scientific review strategy that limits bias by the systematic assembly, critical appraisal, and synthesis of all relevant studies on a specific topic. As shown in Figure 1.1, systematic reviews are at the top of the evidence hierarchy pyramid. Clinicians in pursuit of the best evidence, should first search for high‐quality systematic reviews. Since systematic reviews are such an important part of EBM and are instrumental to clinical decision‐making, this chapter provides a brief description of the systematic review process. Figure 1.1 Systematic review processes. If, as is sometimes supposed, science consisted in nothing but the laborious accumulation of facts, it would soon come to a standstill, crushed, as it were, under its own weight… Two processes are thus at work side by side, the reception of new material and the digestion and assimilation of the old [10] A systematic review is a scientific review strategy that limits bias by the systematic assembly, critical appraisal, and synthesis of all relevant studies on a specific topic. Table 1.1 presents the six steps for Evidence‐based Obstetrics. The first four of these are covered by, and critical to, systematic review. Therefore, busy clinicians can shortcut these steps if they are able to find a high‐quality systematic review that answers their clinical question. Table 1.1 Steps for evidence‐based obstetrics Each of these steps is covered briefly below. A prudent question is one‐half of wisdom [11] Sir Francis Bacon Questions arise every day a clinician cares for patients: some they can answer easily, others they know where to find the answers quickly, and many require investigation. The ability to take an everyday dilemma and turn it into an answerable and searchable question is important not only for systematic reviews, but also for good clinical care. Questions often fall into specific categories: incidence/prevalence, causation/etiology, screening, diagnostic, therapeutic/treatment, prevention, outcomes (benefits and/or harms), prognostic, and they can be expressed as, “In patients with…how effective is…compared with…for the outcome[s] of…”. Formulating an answerable and relevant question is a critical foundational step to determining the relevant scope of a review; too big and the review may not be feasible, too narrow and the results may not be relevant. Systematic review questions are often formulated according to a PICOTS format, that is, Population, Intervention, Comparator, Outcome, Timing, and Setting (Table 1.2).
Evidence‐based medicine in obstetrics and gynecology
History of obstetrics and evidence‐based medicine
What is evidence‐based medicine?
Systematic review processes
1. Formulate a clear clinical question
2. Search the literature and identify relevant reviews and studies
3. Critically appraise individual studies and the overall body of evidence
4. Synthesize results given context and patient factors
5. Implement
6. Evaluate the application into clinical practice
Formulating the question
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