Article type
Year
Abstract
Background: There is now often more than one systematic review on the same or a similar question, which has led to the development of systematic reviews of systematic reviews (overviews). Overviews offer the opportunity of providing decision makers with a broader summary of evidence and contrasting the results of different reviews on the same question. Little is known about their characteristics so far.
Objectives: We set out to examine a sample of overviews in terms of different descriptive and methodological characteristics, including which databases were searched and how the quality of the included systematic reviews was assessed.
Methods: We searched MEDLINE, DARE, the CDSR and different HTA databases for overviews of systematic reviews. Two reviewers independently screened titles and abstracts of the retrieved citations for eligible publications. Data extraction was conducted by one reviewer and checked by a second.
Results: A total of 99 overviews were eligible. The median publication date was 2008 (interquartile range [IQR]: 2005-2010). The overviews included a median of 15 reviews (IQR: 7 to 35). Typically, four electronic databases were searched for systematic reviews (IQR: 2 to6). The quality of the included reviews was systematically appraised in a good half of the overviews (56/99 [57%]). To assess methodological quality, most overviews used the Oxman&Guyatt Index (24/99 [24%]), followed by AMSTAR (8/99 [8%]) and PRISMA/QUORUM (5/99 [5%]). Primary studies published after the search date of the most recent included review were included in 5 overviews [5%].
Conclusions: Overviews should use rigorous methods, if they ought to be a useful tool in health care decision making. The use of a quality assessment tool can help to determine if eligible reviews meet minimum quality requirements. In our sample only a small proportion of overviews used a validated quality assessment tool.
Objectives: We set out to examine a sample of overviews in terms of different descriptive and methodological characteristics, including which databases were searched and how the quality of the included systematic reviews was assessed.
Methods: We searched MEDLINE, DARE, the CDSR and different HTA databases for overviews of systematic reviews. Two reviewers independently screened titles and abstracts of the retrieved citations for eligible publications. Data extraction was conducted by one reviewer and checked by a second.
Results: A total of 99 overviews were eligible. The median publication date was 2008 (interquartile range [IQR]: 2005-2010). The overviews included a median of 15 reviews (IQR: 7 to 35). Typically, four electronic databases were searched for systematic reviews (IQR: 2 to6). The quality of the included reviews was systematically appraised in a good half of the overviews (56/99 [57%]). To assess methodological quality, most overviews used the Oxman&Guyatt Index (24/99 [24%]), followed by AMSTAR (8/99 [8%]) and PRISMA/QUORUM (5/99 [5%]). Primary studies published after the search date of the most recent included review were included in 5 overviews [5%].
Conclusions: Overviews should use rigorous methods, if they ought to be a useful tool in health care decision making. The use of a quality assessment tool can help to determine if eligible reviews meet minimum quality requirements. In our sample only a small proportion of overviews used a validated quality assessment tool.