Factor: Quality of Evidence
The higher the quality of evidence the greater the probability that a strong recommendation is indicated. e.g. strong recommendation that patients with AF at moderate to high risk of stroke be treated with oral anticoagulants.
Factor: Difference between desirable and undesirable effects
The greater the difference between desirable and undesirable effects the greater the probability that a strong recommendation is indicated e.g. strong recommendation that patients with AF ≥ 48 hr duration receive oral anticoagulation therapy for at least 3 weeks prior to planned cardioversion and 4 weeks following.
Factor: Values and Preferences
The greater the variation or uncertainty in values and preferences, the higher the probability that a conditional recommendation is indicated e.g. ASA may be a reasonable alternative to oral anticoagulant therapy in patients at low risk of stroke.
Factor: Cost
The higher the cost the lower the likelihood that a strong recommendation is indicated e.g. conditional recommendation for catheter ablation as first line therapy for AF.

Modified with permission from: Guyatt GH, et al. BMJ 2008;336:926