McMaster Premium LiteratUre Service (PLUS) performed well for identifying new studies for updated Cochrane reviews

OBJECTIVE: We compared the performance of McMaster Premium LiteratUre Service (PLUS) and Clinical Queries (CQs) to that of the Cochrane Controlled Trials Register, MEDLINE, and EMBASE for locating studies added during an update of reviews. STUDY DESIGN AND SETTING: A sample of new studies in updated Cochrane systematic reviews was used as a reference standard. Searches were performed for each study in each database. Where a new study was not indexed in PLUS, we examined the effect on the review of excluding the study. RESULTS: Ninety-eight updated Cochrane reviews were identified. For the 87 reviews with a usable meta-analysis, PLUS contained all new studies for 13 reviews. No statistically significant difference between PLUS and non-PLUS new studies was found when ratio of odds ratios (RORs) were pooled across 39 reviews (ROR(⊕/⊖): 0.99; 95% confidence interval: 0.87-1.14). Thirty-five updated reviews had no new studies indexed in PLUS, but conclusions were seldom altered by addition of new studies. CONCLUSIONS: PLUS included less than a quarter of the new studies in Cochrane updates, but most reviews appeared unaffected by the omission of these studies. Reviewers should consider adopting PLUS and CQ filters to improve the efficiency of keeping their reviews up to date.