Table 1.2Strength of evidence corresponding to each level of recommendation

GradeStrength of evidence
ADirectly based on level 1 evidence
BDirectly based on level 2 evidence or extrapolated recommendation from level 1 evidence
CDirectly based on level 3 evidence or extrapolated recommendation from either level 1 or 2 evidence
DDirectly based on level 4 evidence or extrapolated recommendation from either level 1, 2 or 3 evidence
Good practice point (GPP)The view of the Guideline Development Group
NICE Technology AppraisalRecommendation taken from a NICE Technology Appraisal

From: 1, Introduction

Cover of Fertility
Fertility: Assessment and Treatment for People with Fertility Problems.
NICE Clinical Guidelines, No. 11.
National Collaborating Centre for Women's and Children's Health (UK).
London (UK): RCOG Press; 2004 Feb.
Copyright © 2004, National Collaborating Centre for Women’s and Children’s Health.

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