Background Guideline producers use various methods to grade their recommendations. The Canadian Task Force on Preventive Health Care (CTFPHC) previously assigned letter grades to their recommendations based on an evaluation of the evidence considering only study design. The CTFPHC now uses GRADE (Grading of Recommendations Assessment, Development and Evaluation), which considers the quality of the evidence and the strength of the recommendations.

Objectives The objectives were to develop a tool that would allow interpretation of the previous CTFPHC grading system to GRADE to enable comparison of guidelines.

Methods A comparison and mapping of each level of evidence and strength of recommendation for each grading system was undertaken. The methods working group and the knowledge translation working group of the CTFPHC reviewed the mapping system, which was then tested with a previous CTFPHC recommendation from 2001.

Results An interpretation tool which maps the level of evidence and the strength of recommendation was created and applied to a previous CTFPHC recommendation statement.

Implications for Guideline Developers/Users The tool is not meant to be a perfect system and does not require a formal assessment of the evidence from former guidelines. The evidence from previous guidelines is not assessed using GRADE, but rather interpreted for GRADE language. This tool will be useful in helping guideline developers compare guidelines using different grading systems and will allow the CTFPHC to compare previous guidelines to GRADE. This tool may also be applied when critically appraising guidelines from other guideline development groups.