#CECEM Bridging the Gap between Evidence Based Practice and Practice Based Evidence

15 06 2009

cochrane-symbol A very interesting presentation at the CECEM was given by the organizer of this continental Cochrane meeting, Rob de Bie. De Bie is Professor of Physiotherapy Research and director of Education of the Faculty of Health within the dept. of Epidemiology of the Maastricht University. He is both a certified physiotherapist and an epidemiologist. Luckily he kept the epidemiologic theory to a minimum. In fact he is a very engaging speaker who keeps your attention to the end.


While guidelines were already present in the Middle Ages in the form of formalized treatment of daily practice, more recently clinical guidelines have emerged. These are systematically developed statements which assists clinicians and patients in making decisions about appropriate treatement for specific conditions.

Currently, there are 3 kinds of guidelines, each with its own shortcomings.

  • Consensus based. Consensus may be largely influenced by group dynamics
    Consensus = non-sensus and Consensus guidelines are guidelies.
  • Expert based. Might be even worse than consensus. It can have all kind of biases, like expert and opinion bias or external financing.
  • Evidence based. Guideline recommendations are based on best available evidence, deals with specific interventions for specific populations and are based on a systematic approach.

The quality of Evidence Based Guidelines depends on whether the evidence is good enough, transparent, credible, available, applied and not ‘muddled’ by health care insurers.
It is good to realize that some trials are never done, for instance because of ethical considerations. It is also true that only part of what you read (in the conclusions) has actually be done and some trials are republished several times, each time with a better outcome…

Systematic reviews and qualitatively good trials that don’t give answers.

Next Rob showed us the results of a study ( Jadad and McQuay in J. Clin. Epidemiol. ,1996) with efficacy as stated in the review plotted on the X-axis and the Quality score on the Y-axis. Surprisingly meta-analysis of high quality were less likely to produce positive results. Similar results were also obtained by Suttorp et al in 2006. (see Figure below)

12066264  rob de bie CECEM

Photo made by Chris Mavergames

There may be several reasons why good trials not always give good answers. Well known reasons are  the lack of randomization or blinding. However Rob focused on a less obvious reason. Despite its high level of evidence, a Randomized Controlled Trial (RCT) may not always be suitable to provide good answers applicable to all patients, because RCT’s often fail to reflect the true clinical practice. Often, the inclusion of patients in RCT’s is selective: middle-aged men with exclusion of co-morbidity. Whereas co-morbidity occurs in > 20% of the people of 60 years and older and in >40% of the people of 80 years and older (André Knottnerus in his speech).

Usefulness of a Nested Trial Cohort Study coupled to an EHR to study interventions.

Next, Rob showed that a nested Trial cohort study can be useful to study the effectiveness of  interventions. He used this in conjunction with an EHR (electronic health record), which could be accessed by practitioner and patient.

One of the diseases studied in this way, was Intermittent Claudication. Most commonly Intermittent Claudication is a manifestation of  peripheral arterial disease in the legs, causing pain and cramps in the legs while walking (hence the name). The mortality is high: the 5 year mortality rates are in between those of colorectal cancer and Non-Hodgkin Lymphoma. This is related to the underlying atherosclerosis.

There are several risk factors, some of which cannot be modified, like hereditary factors, age and gender. Other factors, like smoking, diet, physical inactivity and obesity can be tackled. These factors are interrelated.

Rob showed that, whereas there may be an overall null effect of exercise in the whole population, the effect may differ per subgroup.

15-6-2009 3-06-19 CI 1

  • Patients with mild disease and no co-morbidity may directly benefit from exercise-therapy (blue area).
  • Exercise has no effect on smokers, probably because smoking is the main causative factor.
  • People with unstable diabetes first show an improvement, which stabilized after a few weeks due to hypo- or hyperglycaemia induced by the exercise,
  • A similar effect is seen in COPD patients, the exercise becoming less effective because the patients become short of breath.

It is important to first regulate diabetes or COPD before continuing the exercise therapy. By individually optimizing the intervention(s) a far greater overall effect is achieved: 191% improval in the maximal (pain-free) walking distance compared to for instance <35% according to a Cochrane Systematic Review (2007).

Another striking effect: exercise therapy affects some of the prognostic factors: whereas there is no effect on BMI (this stays an important risk factor), age and diabetes become less important risk factors.

15-6-2009 3-35-10 shift in prognostic factors

Because guidelines are quickly outdated, the findings are directly implemented in the existing guidelines.

Another astonishing fact: the physiotherapists pay for the system, not the patient nor the government.

More information can be found on https://www.cebp.nl/. Although the presentation is not (yet?) available on the net, I found a comparable presentation here.

** (2009-06-15) Good news: the program and all presentations can now be viewed at: https://www.cebp.nl/?NODE=239