How can Canadian guideline recommendations be tested?

Potential for harm

Few guidelines have been tested to determine their effect on patient care or clinical outcomes despite calls for testing. For example, The Journal of the American Medical Association’s Users’ Guides to the Medical Literature series includes the question: “Has the guideline been subjected to peer-review and testing?”3 More than 20 years ago, the Institute of Medicine decried the lack of attention to the effect of guidelines on patient care:

…Relatively few steps were underway or planned to evaluate the impact of guidelines on the cost, quality and outcomes of care and on the patient and practitioner satisfaction. This neglect is unfortunate because the effectiveness of guidelines cannot be taken for granted.4

Current tools for assessing guidelines (Appraisal of Guidelines for Research and Evaluation and GuideLine Implementability Appraisal)5^,6 focus on methodologic issues related to the gathering of evidence and development of guidelines, but they do not consider whether the guidelines have been tested.

Most Canadian clinical practice guidelines have not been tested. In contrast, several clinical prediction rules developed in Canada (e.g., the Ottawa Ankle Rules) have been tested in a variety of clinical settings and in multiple countries.7

Elements of the untested Canadian clinical practice guidelines may be harmful in certain clinical contexts, just as guidelines in other countries have caused harm. Linden and Schotte1 found that general practitioners exposed to depression guidelines prescribed doxepin at higher doses to patients with mild depression; these patients had lower rates of symptom improvement than patients cared for by physicians in the control group. The authors concluded that “guidelines should be empirically tested before being called ‘evidence based’.” A Dutch guideline that combined recommendations related to asthma and chronic obstructive pulmonary disease led to an appropriate decrease in inhaled corticosteroid prescriptions for patients with chronic obstructive pulmonary disease, but they also led to an inappropriate decrease in inhaled corticosteroid prescriptions for patients with asthma.2

Difficulty assessing effect on care

It would be impractical to conduct randomized controlled trials of guideline use on clinical outcomes for every version of every guideline. Most of the outcomes of interest (e.g., macrovascular complications of diabetes) take years or decades to accrue in significant numbers. Even for outcomes that appear sooner (e.g., asthma exacerbations), field trials would still be too expensive for guideline developers who struggle to find resources to support the development and dissemination of guidelines. Control group contamination would also be a problem when guidelines are widely disseminated. Even if all of these obstacles were overcome, the results of randomized controlled trials would not necessarily show which parts of guidelines were helpful and which were not. More practical methods for assessing the effect of guideline recommendations on care are needed.

Potential solutions

We suggest public consultation, clinical vignette studies and performance measures as 3 pragmatic methods for testing clinical practice guidelines. These methods can be used before publication of guidelines or after dissemination to help determine if the recommendations are acceptable, understandable and helpful to clinicians and patients. The strengths and limitations of each method (Table 1) should be considered when deciding which is most appropriate.

Public consultation allows clinicians to comment on draft guidelines before widespread dissemination. Clinicians who think that the recommendations are confusing, impractical or unlikely to be helpful can have their feedback incorporated before the guidelines are finalized. The National Institute of Clinical Studies in Australia displays draft guidelines on its website and has a systematic submission process for comments and suggestions by the scientific community; the guideline authors then review and incorporate the suggestions before the final document is complete.8

Clinical vignette studies can be used to test the understandability of guidelines before publication. Clinical practice guideline recommendations are the result of a complex process involving a number of people, and users might misinterpret the guidelines. Clinical vignette performance is a validated and accurate measure of the process of care.9 Different versions of a recommendation (e.g., text v. algorithm) can be put head-to-head to determine which one leads to better clinical decisions. This allows rapid feedback to guideline developers about contentious recommendations. Shekelle and colleagues10 used clinical vignettes in randomized controlled trials to compare specific and vague guidelines for ordering electrodiagnostic tests for patients with back pain; they found that vague guidelines increased the frequency of inappropriate test ordering, whereas specific guidelines decreased inappropriate test ordering.

Performance measures should be included in guidelines so that the developers can solicit feedback as to how the measures change after the guidelines are implemented. This is a practical way to determine the effect of guideline recommendations on patient outcomes. For example, Hypertension Canada’s Outcomes Research Task Force observed that an 84.4% increase in prescriptions for antihypertensive medications between 1999 and 2006 was associated with decreases in mortality from stroke, heart failure and myocardial infarction.11 Carefully selected performance measures can be used to gauge the effect on quality of care, as practised by the National Institute for Health and Clinical Excellence in the United Kingdom.12 Feedback about the effect of a previous version of a guideline on performance measures should be incorporated in later versions.

Conclusion

Clinicians should preferentially use clinical practice guidelines that have been tested. Existing methods (e.g., public consultation, performance measures) and new methods (e.g., clinical vignettes) for testing guidelines should be regularly applied to Canadian guidelines to ensure that clinical practice guidelines improve patient care.

• Most clinical practice guidelines are not tested either before or after widespread dissemination, so their effect on clinical outcomes is unknown.

• It is difficult to determine the effect of clinical practice guidelines on clinical outcomes because trials are impractical.

• Guidelines can be tested using public consultations and clinical vignettes before widespread dissemination and by use of performance measures after dissemination.

• Clinicians should preferentially use clinical practice guidelines that have been tested.