• The typical Cochrane review. How many trials? How many participants?

    16 February 2018

    OBJECTIVES: To describe the number of trials and participants in a typical systematic review from The Cochrane Database of Systematic Reviews. METHODS: The number of trials in 1,000 Cochrane systematic reviews in issue 1, 2001 of The Cochrane Database of Systematic Reviews was counted for three categories of trial: included trials, ongoing trials, and trials awaiting assessment for inclusion. (The term trial is used in this paper, although a small number of Cochrane reviews include studies that are not trials.) The total number of participants in included trials was extracted from a sample of reviews. RESULTS: A total of 9,778 trials were included in the Cochrane reviews. There were a further 356 ongoing trials and 1,138 trials awaiting assessment for inclusion. A typical review contained six included trials. Forty percent of the reviews listed ongoing trials and/or trials awaiting assessment for inclusion. Based on a sample of 258 reviews, the median number of participants per review was 945 (interquartile range, 313 to 2,511) per review and 118 (interquartile range, 60 to 241) per trial. CONCLUSION: This report is a descriptive study of the number of trials and participants in a typical Cochrane review from The Cochrane Library, issue 1, 2001.

  • Methodologists and their methods. Do methodologists write up their conference presentations or is it just 15 minutes of fame?

    12 December 2017

    OBJECTIVES: To assess the extent to which abstracts of methodological research, initially presented at meetings on systematic reviews, have gone on to be published as full articles. METHODS: Full publication was assessed in three ways: a search was carried out of The Cochrane Library; a search was conducted using MEDLINE; and a questionnaire was sent to the contact author of each abstract. RESULTS: Approximately half of the abstracts had not been, or were unlikely ever to be, published in full. CONCLUSIONS: The rate of full publication of abstracts related to the methodology of systematic reviews seems similar to that for randomized trials.

  • A study of the references used in Cochrane protocols and reviews. Three bibles, three dictionaries, and nearly 25,000 other things.

    12 December 2017

    OBJECTIVES: To describe the types of report that are cited by protocols and reviews included in the Cochrane Database of Systematic Reviews. METHODS: The citation for each reference included in the Cochrane protocols and reviews published in the Cochrane Database of Systematic Reviews in issue 1, 1999 of The Cochrane Library were categorized by reference type (e.g., journal article, conference proceeding, book chapter, personal communication, Cochrane review). RESULTS: Of a total of 24,913 citations, 21,694 (87.1%) were references to journal articles. There was a significant difference between the proportion of references to studies that were journal articles (12,348 of 13,472; 91.7%) and the proportion of other references in this category (9,346 of 11,441; 81.7%). CONCLUSION: The great majority of studies included in Cochrane reviews at the beginning of 1999 had been published as journal articles.

  • Is there bias in the publication of individual patient data meta-analyses?

    12 December 2017

    OBJECTIVE: There is increasing empirical evidence for the existence of bias in the publication of primary clinical research, with statistically significant results being published more readily, more quickly, and in higher impact journals. Meta-analysis of individual patient data (IPD) may represent a gold standard of "secondary" clinical research, giving the best possible summary of current evidence for a particular question, but publication of these may also be subject to bias. This study aimed to explore which factors might be associated with publication of IPD meta-analyses and to identify potential sources of bias. METHODS: For all known IPD meta-analysis projects in cancer, the responsible investigator was surveyed by means of a questionnaire to determine descriptive characteristics of the meta-analysis, the nature of the results, and details of the publication history. RESULTS: There is no good evidence that overall publication status of meta-analyses in cancer is dependent on the statistical or clinical significance of the results. However, those meta-analyses with nonsignificant results did seem to take longer to publish and were published in lower impact journals compared with those with more striking results. CONCLUSIONS: Based on the current data, there seems to be no strong association between the results of IPD meta-analyses in cancer and publication.

  • Making evidence more wanted: a systematic review of facilitators to enhance the uptake of evidence from systematic reviews and meta-analyses.

    28 January 2018

    CONTEXT: The increased uptake of evidence from systematic reviews is advocated because of their potential to improve the quality of decision making for patient care. Systematic reviews can do this by decreasing inappropriate clinical variation and quickly expediting the application of current, effective advances to everyday practice. However, research suggests that evidence from systematic reviews has not been widely adopted by health professionals. Little is known about the facilitators to uptake of research evidence from systematic reviews and meta-analyses. OBJECTIVE: To review the facilitators to the uptake by decision makers, of evidence from systematic, meta-analyses and the databases containing them. SEARCH STRATEGY: We searched 19 databases covering the full range of publication years, utilised three search engines and also personally contacted investigators. Grey literature and knowledge translation research was particularly sought. Reference lists of primary studies and related reviews were also searched. SELECTION CRITERIA: Studies were included if they reported on the views and perceptions of decision makers on the uptake of evidence from systematic reviews, meta-analyses and the databases associated with them. One investigator screened titles to identify candidate articles, and then two reviewers independently assessed the relevance of retrieved articles to exclude studies that did not meet the inclusion criteria. Quality of the included studies was also assessed. DATA EXTRACTION: Using a pre-established taxonomy, two reviewers described the methods of included studies and extracted data that were summarised in tables and then analysed. Differences were resolved by consensus. RESULTS: Of articles initially identified, we selected unique published studies describing at least one facilitator to the uptake of evidence from systematic reviews. The 15 unique studies reported 10 surveys, three qualitative investigations and two mixed studies that addressed potential facilitators. Five studies were from Canada, four from the UK, three from Australia, one from Iran and one from South-east Asia (Indonesia, Malaysia, Thailand and the Philippines), with one study covering both Canada and UK. In total, the 15 studies covered eight countries from four continents. Of 2495 participants in the 15 studies, at least 1343 (53.8%) were physicians. Perceived facilitators to the use of evidence from systematic reviews varied. The 15 studies yielded 54 potential facilitators to systematic review uptake. The five most commonly reported perceived facilitators to uptake of evidence from systematic reviews were the following: the perception that systematic reviews have multiple uses for improving knowledge, research, clinical protocols and evidence-based medicine skills (6/15); a content that included benefits, harms and costs and is current, transparent and timely (6/15); a format with a 1:3:25 staged access and executive summary (5/15); training in use (4/15); and peer-group support (4/15). CONCLUSION: The results expand our understanding of how multiple factors act as facilitators to optimal clinical practice. This systematic review reveals that interventions to foster uptake of evidence from systematic reviews, meta-analyses and The Cochrane Library can build on a broad range of facilitators.

  • Methadone dose and neonatal abstinence syndrome-systematic review and meta-analysis.

    16 March 2018

    AIM: To determine if there is a relationship between maternal methadone dose in pregnancy and the diagnosis or medical treatment of neonatal abstinence syndrome (NAS). METHODS: PubMed, EMBASE, the Cochrane Library and PsychINFO were searched for studies reporting on methadone use in pregnancy and NAS (1966-2009). The relative risk (RR) of NAS was compared for methadone doses above versus below a range of cut-off points. Summary RRs and 95% confidence intervals (CI) were estimated using random effects meta-analysis. Sensitivity analyses explored the impact of limiting meta-analyses to prospective studies or studies using an objective scoring system to diagnose NAS. RESULTS: A total of 67 studies met inclusion criteria for the systematic review; 29 were included in the meta-analysis. Any differences in the incidence of NAS in infants of women on higher compared with lower doses were statistically non-significant in analyses restricted to prospective studies or to those using an objective scoring system to diagnose NAS. CONCLUSIONS: Severity of the neonatal abstinence syndrome does not appear to differ according to whether mothers are on high- or low-dose methadone maintenance therapy.