Cochrane Collaboration

About: Cochrane Collaboration is a nonprofit organization based out in Oxford, United Kingdom. It is known for research contribution in the topics: Systematic review & Randomized controlled trial. The organization has 1995 authors who have published 3928 publications receiving 382695 citations.

Development of the Cochrane Collaboration's CENTRAL Register of controlled clinical trials.

Abstract: The Cochrane Collaboration has established a centralized database of controlled trials and other studies of health care interventions (called CENTRAL) that serves as the best available resource for all those preparing and maintaining systematic reviews or otherwise searching for trials. CENTRAL is available on The Cochrane Library. This article describes the history and methods of CENTRAL’s development and the results of an analysis of the current composition of CENTRAL. As of September 2000, CENTRAL contained almost 300,000 citations to reports of trials, contributed mainly by Cochrane Groups and Centers around the world. Development of CENTRAL has been an ambitious, scholarly undertaking and has resulted in a valuable resource: CENTRAL includes citations to controlled trials that may not be indexed in MEDLINE, EMBASE, or other bibliographic databases; citations published internationally in many languages; and citations that are available only in conference proceedings or other hard-to-access sources.

Discrepancies in sample size calculations and data analyses reported in randomised trials: comparison of publications with protocols.

Abstract: Objective To evaluate how often sample size calculations and methods of statistical analysis are pre-specified or changed in randomised trials. Design Retrospective cohort study. Data source Protocols and journal publications of published randomised parallel group trials initially approved in 1994-5 by the scientific-ethics committees for Copenhagen and Frederiksberg, Denmark (n=70). Main outcome measure Proportion of protocols and publications that did not provide key information about sample size calculations and statistical methods; proportion of trials with discrepancies between information presented in the protocol and the publication. Results Only 11/62 trials described existing sample size calculations fully and consistently in both the protocol and the publication. The method of handling protocol deviations was described in 37 protocols and 43 publications. The method of handling missing data was described in 16 protocols and 49 publications. 39/49 protocols and 42/43 publications reported the statistical test used to analyse primary outcome measures. Unacknowledged discrepancies between protocols and publications were found for sample size calculations (18/34 trials), methods of handling protocol deviations (19/43) and missing data (39/49), primary outcome analyses (25/42), subgroup analyses (25/25), and adjusted analyses (23/28). Interim analyses were described in 13 protocols but mentioned in only five corresponding publications. Conclusion When reported in publications, sample size calculations and statistical methods were often explicitly discrepant with the protocol or not pre-specified. Such amendments were rarely acknowledged in the trial publication. The reliability of trial reports cannot be assessed without having access to the full protocols.

Reporting, updating, and correcting systematic reviews of the effects of health care.

Abstract: The recent growth in the numbers of published systematic reviews reflects growing recognition of their importance for improving knowledge about the effects of health care. In Britain the NHS R&D Programme has established two centres to prepare systematic reviews of existing information, and the Cochrane Collaboration--an international network of individuals and institutions--evolved to produce systematic, periodically updated reviews of randomised controlled trials. The large amount of existing evidence that needs to be considered creates a problem for the reporting of systematic reviews: the need to ensure that methods and results of systematic reviews are adequately described has to be reconciled with the limited space available in printed journals. A possible solution is the use of electronic publications: reviews could be published simultaneously in a short, printed form and in a more detailed electronic form. Electronic publications also have the advantage of the ease with which reviews may be updated as new evidence becomes available or mistakes are identified.

Instream flow needs in streams and rivers: the importance of understanding ecological dynamics

Abstract: Resource managers have traditionally had to rely on simple hydrological and habitat-association methods to predict how changes in river flow regimes will affect the viability of instream populations and communities. Yet these systems are characterized by dynamic feedbacks among system components, a high degree of spatial and temporal variability, and connectivity between habitats, none of which can be adequately captured in the commonly employed management methods. We argue that process-oriented ecological models, which consider dynamics across scales and levels of biological organization, are better suited to guide flow regime management. We review how ecological dynamics in streams and rivers are shaped by a combination of the flow regime and internal feedbacks, and proceed to describe ecological modeling tools that have the potential to characterize such dynamics. We conclude with a suggested research agenda to facilitate the inclusion of ecological dynamics into instream flow needs assessments.

Coblation versus other surgical techniques for tonsillectomy.

Abstract: Background Tonsillectomy is a very common operation and is performed using various surgical methods. Coblation is a popular method because it purportedly causes less pain than other surgical methods. However, the superiority of coblation is unproven. Objectives To compare the effects of coblation tonsillectomy for chronic tonsillitis or tonsillar hypertrophy with other surgical techniques, both hot and cold, on intraoperative morbidity, postoperative morbidity and procedural cost. Search methods The Cochrane ENT Information Specialist searched the ENT Trials Register; Central Register of Controlled Trials (CENTRAL 2017, Issue 3); PubMed; Ovid Embase; CINAHL; Web of Science; ClinicalTrials.gov; ICTRP and additional sources for published and unpublished trials. The date of the search was 20 April 2017. Selection criteria Randomised controlled trials (RCTs) of children and adults undergoing tonsillectomy with coblation compared with any other surgical technique. This review is limited to trials of extracapsular (traditional) tonsillectomy and excludes trials of intracapsular tonsil removal (tonsillotomy). Data collection and analysis We used the standard Cochrane methods. Our primary outcomes were: patient-reported pain using a validated pain scale at postoperative days 1, 3 and 7; intraoperative blood loss; primary postoperative bleeding (within 24 hours) and secondary postoperative bleeding (more than 24 hours after surgery). Secondary outcomes were: time until resumption of normal diet, time until resumption of normal activity, duration of surgery and adverse effects including blood transfusion and the need for reoperation. We used GRADE to assess the quality of the evidence for each outcome; this is indicated in italics. Main results We included 29 studies, with a total of 2561 participants. All studies had moderate or high risk of bias. Sixteen studies used an adequate randomisation technique, however the inability to mask the surgical teams and/or provide adequate methods to mitigate the risk of bias put nearly all studies at moderate or high risk of detection and measurement bias for intraoperative blood loss, and primary and secondary bleeding. In contrast most studies (20) were at low risk of bias for pain assessment. Most studies did not report data in a manner permitting meta-analysis. Most studies did not clearly report the participant characteristics, surgical indications or whether patients underwent tonsillectomy or adenotonsillectomy. Most studies reported that tonsillitis (infection) and/or tonsillar hypertrophy (obstruction) were the indication for surgery. Seven studies included only adults, 16 studies included only children and six studies included both. Pain At postoperative day 1 there is very low quality evidence that patients in the coblation group had less pain, with a standardised mean difference (SMD) of -0.79 (95% confidence interval (CI) -1.38 to -0.19; 538 participants; six studies). This effect is reduced a SMD of -0.44 (95% CI -0.97 to 0.09; 401 participants; five studies; very low-quality evidence) at day 3, and at day 7 there is low quality evidence of little or no difference in pain (SMD -0.01, 95% CI -0.22 to 0.19; 420 participants; five studies). Although this suggests that pain may be slightly less in the coblation group between days 1 and 3, the clinical significance is unclear. Intraoperative blood loss Methodological differences between studies in the measurement of intraoperative blood loss precluded meta-analysis. Primary and secondary bleeding The risk of primary bleeding was similar (risk ratio (RR) 0.99, 95% CI 0.48 to 2.05; 2055 participants; 25 studies; low-quality evidence). The risk of secondary bleeding was greater in the coblation group with a risk ratio of 1.36 (95% CI 0.95 to 1.95; 2118 participants; 25 studies; low-quality evidence). Using the median of the control group as the baseline risk, the absolute risk in the coblation group was 5% versus 3.6% in the control group. The difference of 1.3% has a 95% CI of 0.2% lower in the coblation group to 3.5% higher. Secondary outcomes Differences in study design and data reporting precluded the identification of differences in the time to resumption of normal diet or activity, or whether there was a difference in the duration of surgery. Although we could not feasibly compare the costs of equipment or operative facility, anaesthetic and surgical fees across different healthcare systems we used duration of surgery as a proxy for cost. Although this outcome was commonly reported in studies, it was not possible to pool the data to determine whether there was a difference. Adverse events other than bleeding were not well reported. It is unclear whether there is a difference in postoperative infections or the need for reoperation. Authors' conclusions The coblation technique may cause less pain on postoperative day 1, but the difference is small and may be clinically meaningless. By postoperative day 3, the difference decreases further and by postoperative day 7 there appears to be little or no difference. We found similar rates of primary bleeding but we cannot rule out a small increased risk of secondary bleeding with coblation. The evidence supporting these findings is of low or very low quality, i.e. there is a very high degree of uncertainty about the results. Moreover, for most outcomes data were only available from a few of the 29 included studies. The current evidence is of very low quality, therefore it is uncertain whether or not the coblation technique has any advantages over traditional tonsillectomy techniques. Despite the large number of studies, failure to use standardised or validated outcome measures precludes the ability to pool data across studies. Therefore, well-conducted RCTs using consistent, validated outcome measures are needed to establish whether the coblation technique has a benefit over other methods. In the included studies we identified no clear difference in adverse events. However, given the rarity of these events, randomised trials lack the power to detect a difference. Data from large-scale registries will provide a better estimate of any difference in these rare outcomes.