Quality of Cochrane reviews: assessment of sample from 1998.
OBJECTIVE
To assess the quality of Cochrane reviews.


METHODS
Ten methodologists affiliated with the Cochrane Collaboration independently examined, in a semistructured way, the quality of reviews first published in 1998. Each review was assessed by two people; if one of them noted any major problems, they agreed on a common assessment. Predominant types of problem were categorised.


METHODS
Cyberspace collaboration coordinated from the Nordic Cochrane Centre.


METHODS
All 53 reviews first published in issue 4 of the Cochrane Library in 1998.


METHODS
Proportion of reviews with various types of major problem.


RESULTS
No problems or only minor ones were found in most reviews. Major problems were identified in 15 reviews (29%). The evidence did not fully support the conclusion in nine reviews (17%), the conduct or reporting was unsatisfactory in 12 reviews (23%), and stylistic problems were identified in 12 reviews (23%). The problematic conclusions all gave too favourable a picture of the experimental intervention.


CONCLUSIONS
Cochrane reviews have previously been shown to be of higher quality and less biased on average than other systematic reviews, but improvement is always possible. The Cochrane Collaboration has taken steps to improve editorial processes and the quality of its reviews. Meanwhile, the Cochrane Library remains a key source of evidence about the effects of healthcare interventions. Its users should interpret reviews cautiously, particularly those with conclusions favouring experimental interventions and those with many typographical errors.
Olsen
O
O
Nordic Cochrane Centre, Rigshospitalet, Dept 7112, Blegdamsvej 9, DK-2100 Copenhagen Ø, Denmark.
Middleton
P
P
Ezzo
J
J
Gøtzsche
P C
PC
Hadhazy
V
V
Herxheimer
A
A
Kleijnen
J
J
McIntosh
H
H
D015982:Bias; D019992:Databases as Topic / Q000592:standards*; D019317:Evidence-Based Medicine / Q000379:methods / Q000592:standards; D006801:Humans; D015201:Meta-Analysis as Topic; D012196:Review Literature as Topic