Evidence based medicine: a movement in crisis?
Written by Editor   
Wednesday, June 25, 2014 12:08 PM

Although evidence based medicine has had many benefits, it has also had some negative unintended consequences. The authors of this study offer a preliminary agenda for the movement’s renaissance, refocusing on providing useable evidence that can be combined with context and professional expertise so that individual patients get optimal treatment.  

It is more than 20 years since the evidence based medicine working group announced a “new paradigm” for teaching and practising clinical medicine. Tradition, anecdote, and theoretical reasoning from basic sciences would be replaced by evidence from high quality randomised controlled trials and observational studies, in combination with clinical expertise and the needs and wishes of patients.

Evidence based medicine quickly became an energetic intellectual community committed to making clinical practice more scientific and empirically grounded and thereby achieving safer, more consistent, and more cost effective care.

Two decades of enthusiasm and funding have produced numerous successes for evidence based medicine. Despite these and many other successes, wide variation in implementing evidence based practice remains a problem.

The first problem is that the evidence based “quality mark” has been misappropriated and distorted by vested interests. In particular, the drug and medical devices industries increasingly set the research agenda. They define what counts as disease and predisease “risk states” (such as low bone density, treatable with alendronate). They also decide which tests and treatments will be compared in empirical studies and choose (often surrogate) outcome measures for establishing “efficacy.”

Furthermore, by overpowering trials to ensure that small differences will be statistically significant, setting inclusion criteria to select those most likely to respond to treatment, manipulating the dose of both intervention and control drugs, using surrogate endpoints, and selectively publishing positive studies, industry may manage to publish its outputs as “unbiased” studies in leading peer reviewed journals. Use of these kinds of tactic in studies of psychiatric drugs sponsored by their respective manufacturers enabled them to show that drug A outperformed drug B, which outperformed drug C, which in turn outperformed drug A. One review of industry sponsored trials of antidepressants showed that 37 of 38 with positive findings, but only 14 of 36 with negative findings, were published.

Evidence based medicine’s quality checklists and risk of bias tools may be unable to detect the increasingly subtle biases in industry sponsored studies. Some so called evidence based policies seem to be based largely on political conviction. Critics have condemned the role of the drug industry in influencing the policy makers who introduced them.

The second aspect of evidence based medicine’s crisis (and yet, ironically, also a measure of its success) is the sheer volume of evidence available. In particular, the number of clinical guidelines is now both unmanageable and unfathomable. 

Evidence based medicine is, increasingly, a science of marginal gains.  Large trials designed to achieve marginal gains in a near saturated therapeutic field typically overestimate potential benefits and underestimate harms. The 74 year old who is put on a high dose statin because the clinician applies a fragment of a guideline uncritically and who, as a result, develops muscle pains that interfere with her hobbies and ability to exercise, is a good example of the evidence based tail wagging the clinical dog. In such scenarios, the focus of clinical care shifts insidiously from the patient (this 74 year old woman) to the population subgroup (women aged 70 to 75) and from ends (what is the goal of investigation or treatment in this patient?) to means (how can we ensure that everyone in a defined denominator population is taking statins?).

As the examples above show, evidence based medicine has drifted in recent years from investigating and managing established disease to detecting and intervening in non-diseases. Risk assessment using “evidence based” scores and algorithms now occurs on an industrial scale, with scant attention to the opportunity costs or unintended human and financial consequences.

Well intentioned efforts to automate use of evidence through computerised decision support systems, structured templates, and point of care prompts can crowd out the local, individualised, and patient initiated elements of the clinical consultation. For example, when a clinician is following a template driven diabetes check-up, serious non-diabetes related symptoms that the patient mentions in passing may not by documented or acted on. Inexperienced clinicians may (partly through fear of litigation) engage mechanically and defensively with decision support technologies, stifling the development of a more nuanced clinical expertise that embraces accumulated practical experience, tolerance of uncertainty, and the ability to apply practical and ethical judgment in a unique case.

Templates and point of care prompts also contribute to the creeping managerialism and politicisation of clinical practice. As Harrison and Checkland observe: “As the language of EBM becomes ever more embedded in medical practice, and as bureaucratic rules become the accepted way to implement ‘the best’ evidence, its requirements for evidence are quietly attenuated in favour of an emphasis on rules.”

Finally, as the population ages and the prevalence of chronic degenerative diseases increases, the patient with a single condition that maps unproblematically to a single evidence based guideline is becoming a rarity. Even when primary studies were designed to include participants with multiple conditions, applying their findings to patients with particular comorbidities remains problematic. Multimorbidity (a single condition only in name) affects every person differently and seems to defy efforts to produce or apply objective scores, metrics, interventions, or guidelines. Increasingly, the evidence based management of one disease or risk state may cause or exacerbate another—most commonly through the perils of polypharmacy in the older patient.

To deliver real evidence based medicine, the movement’s stakeholders must be proactive and persistent. Patients must demand better evidence, better presented, better explained, and applied in a more personalised way with sensitivity to context and individual goals. 

Much progress has been made and lives have been saved through the systematic collation, synthesis, and application of high quality empirical evidence. However, evidence based medicine has not resolved the problems it set out to address (especially evidence biases and the hidden hand of vested interests), which have become subtler and harder to detect. Furthermore, contemporary healthcare’s complex economic, political, technological and commercial context has tended to steer the evidence based agenda towards populations, statistics, risk, and spurious certainty. Despite lip service to shared decision making, patients can be left confused and even tyrannised when their clinical management is inappropriately driven by algorithmic protocols, top-down directives and population targets.

Such problems have led some to argue for the rejection of evidence based medicine as a failed model. Instead we argue for a return to the movement’s founding principles—to individualise evidence and share decisions through meaningful conversations in the context of a humanistic and professional clinician-patient relationship. To deliver this agenda, evidence based medicine’s many stakeholders—patients, clinicians, educators, producers and publishers of evidence, policy makers, research funders, and researchers from a range of academic disciplines—must work together. The government is already moving in this direction as this report notes.   

Source:  http://www.bmj.com/content/348/bmj.g3725