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Table 3 Methodological aspects of previously published guidelines

From: Methods underpinning national clinical guidelines for hypertension: describing the evidence shortfall

Guideline Literature search Grading of evidence Development group
CMA MEDLINE and Cochrane Collaboration searches; reference lists in retrieved articles. Requests to experts and panel members. Recommendations were graded from A-D and were based on assessment of the studies using an algorithm.
A Grade assigned if recommendation was:
– based on an adequate RCT ie, with blinded assessment of outcomes, intention-to-treat analysis, adequate follow-up, and sufficient sample size to detect a clinically important difference with power greater than 80%.
– based on an adequate subgroup analysis
– based on a systematic review in which the comparison arms are derived from head-to head comparisons with the same RCT
A committee with a range of representatives from different bodies. Patient involvement unclear
WHO None described None described Patient involvement unclear
VHA MeSH terms covering key therapies, and study characteristics and design Evidence was graded:
B well-designed clinical studies
C panel consensus
Recommendations were rated:
I usually indicated; always acceptable; useful and effective
IIa acceptable, of uncertain effectiveness, and may be controversial. Weight of evidence in favour of usefulness/effectiveness
IIb acceptable, of uncertain effectiveness and may be controversial. Not well established by evidence, can be helpful and probably not harmful
Thirty-eight individuals. Roles not always clear.
SIGN Systematic literature searches on MEDLINE, Healthstar, EMBASE, Cochrane Library. Based on a published Cochrane review Evidence was graded when obtained from:
Ia: meta-analysis of RCTs Ib: at least 1 RCT
IIa: at least 1 well-designed controlled study without randomisation
IIb: at least one other type of well-designed quasi-experimental study
III: well-designed non-experimental descriptive studies
IV: expert committee reports and/or respected clinical opinion
Recommendations were rated:
A Evidence levels Ia, Ib
B Evidence levels IIa, IIb, III
C Evidence level IV.
Members' names and affiliations listed and conflicts of interest available. Specialist reviewer names given. Age Concern represented.
ESH None described Recommendations not classified upon strength of available evidence. Members' names, affiliations, potential conflicts of interest given. Patient involvement unclear
ICSI None described Research reports were graded as follows:
Primary reports A (RCT) to D (case and cross sectional studies)
Reviews M (Meta-analysis, systematic reviews, decision analysis, cost-benefit analysis, cost-effectiveness study)
R: Narrative review, consensus statement or report
X: Medical opinion
In the 2002 update, some recommendations link to the evidence grade
No details
JNC None described Evidence supporting recommendations for prevention and treatment was classified:
M meta-analysis
Re retrospective analyses (case control)
F prospective follow-up – cohort study
Pr previous review
C clinical interventions (non-randomised)
X cross-sectional population studies (prevalence)
Nine individuals. Contributions were sought from multidisciplinary experts. No mention of patient involvement
SA None described Evidence not described or graded Members' names and affiliation given. Patient involvement unclear
BHS Not described Strength of evidence: Ia (meta analysis of RCTs) to IV expert opinion Strength of recommendation
A Directly based on category I evidence
B Directly based on category II evidence or extrapolated recommendation from category I evidence
C Directly based on category III evidence or extrapolated recommendation from category I or II evidence.
D Directly based on category IV evidence or extrapolated recommendation from category I, II or III evidence
No details given
NICE Search using MEDLINE, EMBASE and CENTRAL, previous systematic reviews, bibliographic seachs as well as contact with subject area experts. Guideline Recommendation and Evidence Grading (GREG [34]) system applied.
Evidence Grade: Interpretation of Evidence
I High Plausible, precisely quantified and not vulnerable to bias.
II Intermediate Plausible but not quantified precisely or may be vulnerable to bias.
III Low Concerns about plausibility or vulnerability to bias.
Recommendation Grade Interpretation of recommendation
A Recommendation Robust evidence
B Provisional Recommendation Recommend with caution
C Consensus Opinion Recommended by consensus
Members names and affiliations given and any potential conflicts of interest. Contributions were sought from multidisciplinary experts. Group included patient representatives