Canadian Task Force (CTF) - Canadian Task Force Methodology

Canadian Task Force Methodology (click here for detailed version)

CTFPHC Methods
Table 1. Grades of Recommendations
Table 2. Quality of Published Evidence
Challenges
Decision Making When Evidence is Unclear

CTFPHC Methods

The Task Force strives to provide a bridge between research findings and clinical preventive practice. When research does not provide clear guidance, this lack of evidence is articulated. A major objective is to help physicians choose tests, immunizations, counselling strategies and other preventive interventions of proven utility and avoid those that lack demonstrated value.

We use a standardized methodology, employing explicit analytic criteria, for evaluating the effectiveness of preventive health care interventions. Key features are to:

make recommendations of graded strength, based on the quality of published medical evidence
place greatest weight on the features of study design and analysis that tend to eliminate or minimize biased results

Table 1 and Table 2 provide a summary of the CTFPHC's grades of recommendations and quality of evidence.

Table 1. Grades of Recommendations

A	Good evidence to support the recommendation that the condition be specifically considered in a PHE.
B	Fair evidence to support the recommendation that the condition be specifically considered in a PHE.
C	Poor evidence regarding inclusion or exclusion of a condition in a PHE, but recommendations may be made on other grounds.
D	Fair evidence to support the recommendation that the condition be specifically excluded from consideration in a PHE.
E	Good evidence to support the recommendation that the condition be specifically excluded from consideration in a PHE.

Table 2. Quality of Published Evidence

I	Evidence from at least 1 properly randomized controlled trial (RCT).
II-1	Evidence from well-designed controlled trials without randomization.
II-2	Evidence from well-designed cohort or case-control analytic studies, preferably from more than 1 centre or research group.
II-3	Evidence from comparisons between times or places with or without the intervention. Dramatic results in uncontrolled experiments could also be included here.
III	Opinions of respected authorities, based on clinical experience, descriptive studies or reports of expert committees.

Some Challenges for Evidence-based Prevention

The CTFPHC has identified that a number of important issues arise during and following the development of clinical preventive guidelines:

there are a relatively large number of "C" Recommendations (due to inconclusive evidence), leaving clinicians to make decisions on other grounds -- this may be frustrating
we need to consider all varieties of benefit and harm associated with any preventive maneuver, including improved quality or length of life, anxiety relieved or money saved, cost, "labelling" and anxiety, including that induced by earlier diagnosis
a "C" Recommendation can serve as a caution to those who have to decide which preventive measures justify public funding
many preventive interventions that have the potential to improve health lie outside the context of the clinician-patient encounter - the prevention of poverty, of violence and of pollution are striking examples
while cost of care is an inescapable and serious consideration, economic analysis of clinical preventive actions is complex and not yet fully developed. It is not yet a major focus of Task Force evaluations
choices may have to be made, on both monetary and ethical grounds, between preventive interventions for unrelated conditions

Decision Making When Evidence is Unclear ("C" Recommendations)

Guiding Factors for Decision-Making:

increase patient involvement in decision-making
minimize harm
advocate major change only on strong proof of need
avoid unnecessary labelling
avoid expensive manoeuvres of unclear benefit
focus on conditions with a high burden of illness
be attentive to special needs of high risk groups

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