Header

UZH-Logo

Maintenance Infos

The quality of evidence for medical interventions does not improve or worsen: a metaepidemiological study of Cochrane reviews


Howick, Jeremy; Koletsi, Despina; Pandis, Nikolaos; Fleming, Padhraig S; Loef, Martin; Walach, Harald; Schmidt, Stefan; Ioannidis, John P A (2020). The quality of evidence for medical interventions does not improve or worsen: a metaepidemiological study of Cochrane reviews. Journal of Clinical Epidemiology, 126:154-159.

Abstract

OBJECTIVES
The objective of the study was to determine the change in quality of evidence in updates of Cochrane reviews that were initially published between January 1, 2013 and June 30, 2014. We used the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) system to document evidence quality.
STUDY DESIGN AND SETTING
We searched the Cochrane Database of Systematic Reviews on March 20, 2020 to identify which of the reviews from the initial (2013/14) sample had been updated. Using the same methods to determine the quality of evidence in the previous analysis, we assessed the quality of evidence for the first-listed primary outcomes in the updated reviews.
RESULTS
Of the 608 reviews in the original sample, 154 had been updated with and 151 contained available data for both original and updated systematic reviews (24.8%). The updated reviews included: 15 (9.9%) with high-quality evidence, 56 (37.1%) with moderate-quality evidence, 47 (31.1%) with low-quality evidence, and 33 (21.9%) with very low-quality evidence. No change in the GRADE quality of evidence was found for most (103, 68.2%) of the updated reviews. The quality of evidence rating was downgraded in 28 reviews (58.3%) and upgraded in 20 (41.7%), although only six reviews were promoted to high quality.
CONCLUSION
Updated systematic reviews continued to suggest that only a minority of outcomes for health care interventions are supported by high-quality evidence. The quality of the evidence did not consistently improve or worsen in updated reviews.

Abstract

OBJECTIVES
The objective of the study was to determine the change in quality of evidence in updates of Cochrane reviews that were initially published between January 1, 2013 and June 30, 2014. We used the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) system to document evidence quality.
STUDY DESIGN AND SETTING
We searched the Cochrane Database of Systematic Reviews on March 20, 2020 to identify which of the reviews from the initial (2013/14) sample had been updated. Using the same methods to determine the quality of evidence in the previous analysis, we assessed the quality of evidence for the first-listed primary outcomes in the updated reviews.
RESULTS
Of the 608 reviews in the original sample, 154 had been updated with and 151 contained available data for both original and updated systematic reviews (24.8%). The updated reviews included: 15 (9.9%) with high-quality evidence, 56 (37.1%) with moderate-quality evidence, 47 (31.1%) with low-quality evidence, and 33 (21.9%) with very low-quality evidence. No change in the GRADE quality of evidence was found for most (103, 68.2%) of the updated reviews. The quality of evidence rating was downgraded in 28 reviews (58.3%) and upgraded in 20 (41.7%), although only six reviews were promoted to high quality.
CONCLUSION
Updated systematic reviews continued to suggest that only a minority of outcomes for health care interventions are supported by high-quality evidence. The quality of the evidence did not consistently improve or worsen in updated reviews.

Statistics

Citations

Dimensions.ai Metrics

Altmetrics

Downloads

1 download since deposited on 07 Oct 2020
1 download since 12 months
Detailed statistics

Additional indexing

Item Type:Journal Article, refereed, further contribution
Communities & Collections:04 Faculty of Medicine > Center for Dental Medicine > Clinic for Orthodontics and Pediatric Dentistry
Dewey Decimal Classification:610 Medicine & health
Scopus Subject Areas:Health Sciences > Epidemiology
Language:English
Date:October 2020
Deposited On:07 Oct 2020 13:38
Last Modified:08 Oct 2020 20:00
Publisher:Elsevier
ISSN:0895-4356
OA Status:Closed
Publisher DOI:https://doi.org/10.1016/j.jclinepi.2020.08.005
PubMed ID:32890636

Download

Closed Access: Download allowed only for UZH members

Content: Accepted Version
Language: English
Filetype: PDF - Registered users only until 29 August 2021
Size: 388kB
View at publisher
Embargo till: 2021-08-29