Objective To explore the differences between large and small studies in rare events meta-analysis. Methods Empirical data were collected from The Cochrane Systematic Review Database from January 2003 to May 2018. Meta-analyses with rare events, binary outcomes involving at least 5 studies, and at least 1 large study were screened. Peto and classical ORs were used to compare the magnitude, direction and P-value. Results A total of 214 meta-analyses were included. Among 214 pairs of ORs of large and small studies, 66 pairs (30.84%) were inconsistent in the direction of ORs based on Peto OR (Kappa =0.33), and 69 pairs (32.24%) were inconsistent in the direction of ORs based on classical OR. The Peto ORs resulted in smaller P-values compared to classic ORs in a substantial (83.18%) number of cases. Conclusion There are considerable differences between large and small studies in the results of meta-analysis of rare events.
Objective To analyze the methodological quality of clinical practice guideline mentioned “evidence-based” in China. Methods We selected clinical guidelines developed based on evidence issued by the Chinese Medical Association in 2010-2012, and meanwhile, we conducted additional search for guidelines on clinical major diseases. Then, we selected literature according to the inclusion and exclusion criteria and evaluated the included guidelines according to 8 items relevant to methodological rigor which were selected from the Appraisal of Guidelines for Research and Evaluation (AGREE II). If the guidelines comply with the item, we recorded 1 point, otherwise 0 point. Results a) Among twenty-two included guidelines, 13 were originated and 9 were updated once every 3 to 5 years. b) Diseases covered stroke, diabetes, chronic hepatitis B, hypertension, pediatric nutrition, etc. c) The number of guideline references were 10 to 218, of which, nine guidelines cited 24 Cochrane systematic reviews (CDSRs), accounted for 2.62% (24/916). Among them, the acute ischemic stroke guideline cited the most (7 CDSRs). d) The number of experts involved in guidelines development was 2 to 95 and guidelines pages were 4 to 150. e) The guidelines’ quality generally scored 4 to 7, most of which described the process of guidelines development. The grades of recommendation were consistent with the levels of evidence. But most of the included guidelines did not clearly described literature research methods, peer reviewer, and update procedures. Conclusion There is a growing trend that clinical guidelines are developed based on evidence in China. However, the quality of reporting and the methodological rigor of guidelines need further improvement. The citation rates of Cochrane systematic reviews in these guidelines were relatively low. We suggest that guideline recommendations should be consistent with the levels of evidence and adapt to local conditions, and relevant support policies for guideline implementation in practice. In future, attention should be paid to the aspects of guideline development methods, reporting standard, guideline accessibility, and standard training for relevant personnel.
This paper reports publication status, authors distribution and the difficulties of producing Cochrane systematic reviews （CSRs） in China to offer new ideas for further development of CSR. in China. Up to Dec. 2005, Chinese authors have published 28 CSRs （1.1%）, 10 of which were indexed by SCI.
Over the past two decades, the International Cochrane Collaboration has completely transformed the mechanism of health decision-making. Cochrane aims to collect, summarize and disseminate the best current research evidence via The Cochrane Library in order to help stakeholders making informed health care decisions. Cochrane began with just a few dozen volunteers and has, over the years, transformed into a truly global and inclusive network, with 37 000 contributors from over 130 countries. Cochrane evidence has long been recognized as high quality and trustworthy international gold standard in health care. In recent years, Cochrane has initiated a number of innovative projects to attract more researchers from different socio-cultural and educational backgrounds. This commentary introduces these new platforms and illustrates the opportunities offered to Chinese researchers by the modern-era Cochrane.
Objective ① To document the way in which allocation concealment is described and coded for studies included in Cochrane Reviews.②To feed back any gaps or miscodings to individual review groups.③ To suggest changes and expansions to advice on how to code and describe allocation concealment methods.Methods The coding and description of methods of allocation concealment for studies included in all 1 596 reviews on issue 1, 2003 of The Cochrane Library are being extracted.So far results are available for 10.8% (173/1 596) of reviews containing 1 844 studies, from 10 Collaborative Review Groups (CRGs).Discrepancies, and inconsistencies with the Cochrane Reviewers’ Handbook, are being documented and analysed.Results The current coding of the adequacy of allocation concealment in studies included in Cochrane reviews is not likely to be very accurate.This is due to failure to describe methods of allocation concealment (38.6% of the sample of 1 844 studies) as well as miscoding (at least an additional 9.2%).The most common method for studies coded A was some variation of envelope use (133/675-19.7% of all A codes). The most common "method" for studies coded B was method unclear or not described in the report of the study (426/665, 64% of all B codes).Conclusions Since adequate allocation concealment is so important in protecting against bias in randomised controlled trials, it needs to be accurately coded and described.We need to improve how this is done for studies included in Cochrane Reviews.Since over half the studies coded as D were likely to have been where reviewers omitted to enter a code, the default should be changed from D to "code not supplied".Structural changes to RevMan are suggested-ideally the addition of a separate new study quality assessment table with fixed headings as well as the facility to enter free text.Suggestions for improving coding in particular reviews will be fed back to CRGs in the next stages of this project.Suggestions for additions to the Cochrane Reviewers’ Handbook are also made.
Objective To assess the effects on labour, maternal, and neonatal outcomes of different techniques and drugs for analgesia during labour. Methods We searched The Cochrane Library (Issue 4, 2006) , MEDLINE (Jan. 1978 to Oct. 2006) and CBMdisc (Jan. 1980 to Oct. 2006) to collect the current best evidence of labor analgesia. Results We included eight Cochrane systematic reviews and six other meta-analyses. The evidence showed that epidural analgesia was associated with a longer second stage of labour, more frequent oxytocin augmentation, higher incidence of instrumental vaginal delivery and maternal fever. But it was unlikely to increase the risk of caesarean section. Conclusion Epidural analgesia is superior to other approaches.
