Writing an Evidence Based Clinical Review Article: Why POEMs Are Better Than DOEs
The journal American Family Physician published a very good "how to" article on this topic a few years ago [Siwek, Gourley, Slawson & Shaughnhessey, Am Fam Physician 2002; 65:251-8] This is one of the best sources to learn why the classic clinical review articles that we practitioners value so highly are quickly becoming obsolete. Although the intended audience is family doctors, substituting "CPO" for "family practitioner" as you read this piece makes the correlation to our field very apparent.
One of the key concepts discussed is the growing recognition by health care experts that just because evidence is scientifically valid does not mean that it is clinically relevant. As our field moves rapidly toward evidence-based practices, we too will undoubtedly struggle with this key concept. But, as relative latecomers to the EBP game, we can benefit from the insights of those who have gone before us.
Disease Oriented Evidence [DOE] has been the mainstay of medical research until very recently, and is typically comprised of easily measurable data points that may not directly relate to patient treatment by the hands-on clinicians. Shaughnessy and Slawson have previously argued that the best articles provide a clinical interpretation of such raw findings that deal with outcomes of importance to patients, such as changes in morbidity, mortality, or quality of life. They term this latter type of scientific evidence Patient Oriented Evidence that Matters [POEM].
They note that these two types of evidence may be in agreement, in disagreement, or have an unknown relationship for any given recommendation. Since the POEM should be what drives clinical practice, they suggest caution in interpreting DOE alone:
"Although prostate-specific antigen (PSA) testing identifies prostate cancer at an early stage, it has not yet been proved that PSA screening improves patient survival."
We must exercise similar caution in interpreting P&O related recommendations to prevent being dazzled by statistically significant information that is clinically irrelevant. Heed the old orthopaedic aphorism that says, "Treat the patient, not the radiographic image".
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These authors further suggest that all peer-reviewed literature be ranked according to the strength of the evidence where A-level is from randomized, controlled trials [RCTs], B-level from well designed but non-randomized trials, and C-level from poorly designed research and expert opinion. Although the overwhelming majority of publications on P&O topics worldwide are currently at level C or lower, we have an opportunity to drive future research toward POEM so that the stronger evidence is also directly useful in the clinical treatment of our patients.
The authors recommend summarizing evidence based statements as follows
- ""To improve morbidity and mortality, most patients in congestive heart failure should be treated with an angiotensin-converting enzyme inhibitor. [Evidence level A, RCT]"
- "The USPSTF recommends that clinicians routinely screen asymptomatic pregnant women 25 years and younger for chlamydial infection. [Evidence level B, nonrandomized clinical trial]"
- "The American Diabetes Association recommends screening for diabetes every three years in all patients at high risk of the disease, including all adults 45 years and older. [Evidence level C, expert opinion]"
When there is no strong scientific evidence to support common practice, they advise statements such as:
- "Physical therapy is traditionally prescribed for the treatment of adhesive capsulitis (frozen shoulder), although there are no randomized outcomes studies of this approach."
Such neutral, factual statements provide the dedicated clinician with guidelines based on the best available evidence, and a clear idea of how "solid" the scientific foundation is for each protocol. When new information suggests altering "conventional" practices, the savvy practitioner can readily determine whether it is higher level evidence that should compel an immediate change or equivalent quality evidence that is not yet persuasive.
The entire article is posted online at [ www.aafp.org/afp/20020115/251.html ].