Article type
Year
Abstract
Background: It is generally believed that exhaustive searches of bibliographic databases are needed for systematic reviews of health care interventions. The CENTRAL database of randomized controlled trials (RCTs) has been built up by exhaustive searching. The CONSORT statement aims to encourage better reporting of RCTs.
Objectives: To assess whether developments in the CENTRAL database, and the CONSORT statement, mean that a simplified RCT search strategy for identifying RCTs now suffices for systematic reviews of health care interventions.
Methods: RCTs used in the Cochrane reviews were identified. A brief RCT search strategy (BRSS), consisting of a search of CENTRAL, and then for variants of the word random across all fields (random$.af.) in MEDLINE and Embase, was devised and run. Any trials included in the meta-analyses, but missed by the BRSS, were identified. The meta-analyses were then re-run, with and without the missed RCTs, and the differences quantified. The proportion of trials with variants of the word random in the title or abstract was calculated for each year. The number of RCTs retrieved by the search Ârandom$.af. was compared to the highly sensitive search strategy (HSSS).
Results: The BRSS had a sensitivity of 94%. It found all journal RCTs in 47of the 57 reviews. The missing RCTs made some significant differences to a small proportion of the total outcomes in only five reviews, but no important differences in conclusions resulted. The percentage of RCTs with random in the title or abstract in pre-CONSORT years (1980-1996) was 61.7%. This increased significantly by 23.5% (95% CI, 12.6% to 34.3%) in post-CONSORT years (1997-2003) to 85.1%. (See Figure below). The search using random$.af. reduced the MEDLINE retrieval by 84%, compared to the HSSS, thereby reducing the manual checking.
Conclusions: A brief RCT search strategy is now sufficient to locate RCTs for systematic reviews in most cases. Exhaustive searching is no longer cost-effective, because in effect it has already been done for CENTRAL. Also, the CONSORT statement appears to be associated with a significant increase in the frequency of 'random' in the titles and abstracts of journal articles, and hence more sensitive retrieval of RCTs using the BRSS.
Objectives: To assess whether developments in the CENTRAL database, and the CONSORT statement, mean that a simplified RCT search strategy for identifying RCTs now suffices for systematic reviews of health care interventions.
Methods: RCTs used in the Cochrane reviews were identified. A brief RCT search strategy (BRSS), consisting of a search of CENTRAL, and then for variants of the word random across all fields (random$.af.) in MEDLINE and Embase, was devised and run. Any trials included in the meta-analyses, but missed by the BRSS, were identified. The meta-analyses were then re-run, with and without the missed RCTs, and the differences quantified. The proportion of trials with variants of the word random in the title or abstract was calculated for each year. The number of RCTs retrieved by the search Ârandom$.af. was compared to the highly sensitive search strategy (HSSS).
Results: The BRSS had a sensitivity of 94%. It found all journal RCTs in 47of the 57 reviews. The missing RCTs made some significant differences to a small proportion of the total outcomes in only five reviews, but no important differences in conclusions resulted. The percentage of RCTs with random in the title or abstract in pre-CONSORT years (1980-1996) was 61.7%. This increased significantly by 23.5% (95% CI, 12.6% to 34.3%) in post-CONSORT years (1997-2003) to 85.1%. (See Figure below). The search using random$.af. reduced the MEDLINE retrieval by 84%, compared to the HSSS, thereby reducing the manual checking.
Conclusions: A brief RCT search strategy is now sufficient to locate RCTs for systematic reviews in most cases. Exhaustive searching is no longer cost-effective, because in effect it has already been done for CENTRAL. Also, the CONSORT statement appears to be associated with a significant increase in the frequency of 'random' in the titles and abstracts of journal articles, and hence more sensitive retrieval of RCTs using the BRSS.