• The Cochrane Collaboration.

    14 May 2018

    The Cochrane Collaboration is an international, not-for-profit organisation that aims to help people make well-informed decisions about health care by preparing, maintaining and promoting the accessibility of systematic reviews of the effects of health-care interventions. Cochrane systematic reviews are prepared according to predefined, explicit methodology, and published in The Cochrane Library. The abstracts and plain English summaries of the reviews are freely available on the Internet. All reviews are prepared and maintained under the editorial control of 50 Cochrane Collaborative Review Groups that focus on (groups of) health problems. The work of Collaborative Review Groups is supported, among others, by people working in Cochrane Fields. Cochrane Fields focus on dimensions of health care other than health problems. To date, the issue of nutrition has not been addressed sufficiently in The Cochrane Collaboration. Nutrition issues are very important for day-to-day health care and the initiatives to establish a new Cochrane Diet and Nutrition (Sub)Field will help to promote the preparation of systematic reviews of nutritional interventions by the variety of Collaborative Review Groups to whom such interventions are relevant. Many issues regarding nutritional interventions, however, are complex, and methodological challenges will have to be overcome. A Cochrane Diet and Nutrition (Sub)Field with experts on nutritional research can help fill this gap and make those reviews more possible.

  • How many do I need? Basic principles of sample size estimation.

    12 December 2017

    BACKGROUND: In conducting randomized trials, formal estimations of sample size are required to ensure that the probability of missing an important difference is small, to reduce unnecessary cost and to reduce wastage. Nevertheless, this aspect of research design often causes confusion for the novice researcher. AIM: This paper attempts to demystify the process of sample size estimation by explaining some of the basic concepts and issues to consider in determining appropriate sample sizes. METHOD: Using a hypothetical two group, randomized trial as an example, we examine each of the basic issues that require consideration in estimating appropriate sample sizes. Issues discussed include: the ethics of randomized trials, the randomized trial, the null hypothesis, effect size, probability, significance level and type I error, and power and type II error. The paper concludes with examples of sample size estimations with varying effect size, power and alpha levels. CONCLUSION: Health care researchers should carefully consider each of the aspects inherent in sample size estimations. Such consideration is essential if care is to be based on sound evidence, which has been collected with due consideration of resource use, clinically important differences and the need to avoid, as far as possible, types I and II errors. If the techniques they employ are not appropriate, researchers run the risk of misinterpreting findings due to inappropriate, unrepresentative and biased samples.

  • [CONSORT 2010 Statement: updated guidelines for reporting parallel group randomised trials (Chinese version)].

    15 June 2018

    The CONSORT statement is used worldwide to improve the reporting of randomised controlled trials. Kenneth Schulz and colleagues describe the latest version, CONSORT 2010, which updates the reporting guideline based on new methodological evidence and accumulating experience. To encourage dissemination of the CONSORT 2010 Statement, this article is freely accessible on bmj.com and will also be published in the Lancet, Obstetrics and Gynecology, PLoS Medicine, Annals of Internal Medicine, Open Medicine, Journal of Clinical Epidemiology, BMC Medicine, and Trials.

  • The origins, evolution, and future of The Cochrane Database of Systematic Reviews.

    27 April 2018

    The Cochrane Database of Systematic Reviews (CDSR) evolved in response to Archie Cochrane's challenge to the medical profession to assemble "a critical summary, adapted periodically, of all ... relevant randomized controlled trials". CDSR has been an electronic publication from its inception and this has meant that Cochrane reviews (i) need not be constrained by lack of space; (ii) can be updated as new information becomes available and when mistakes or other ways of improving them are identified; and (iii) can be cross-linked to other, related sources of relevant information. Although CDSR has become widely cited, it must continue to evolve in the light of technological and methodological developments, and in response to the needs of people making decisions about health care.

  • Carbapenems versus other beta-lactams in treating severe infections in intensive care: a systematic review of randomised controlled trials.

    29 December 2017

    Carbapenems have not been comprehensively compared in clinical trials with fourth-generation cephalosporins (4GC) and antipseudomonal penicillins (APP) in the treatment of severe infections (SI) and febrile neutropenia (FN). A systematic review of CENTRAL, EMBASE, MEDLINE and JICST-EPlus for randomised controlled trials was conducted to establish the currently available evidence. Database searching was supplemented by hand searching and contacting conference organisers. Searching was completed in November 2006 and no restriction was placed on the language of publication. Data were extracted on clinical response, bacteriologic response, all-cause mortality and adverse events. Of the 265 papers identified, 12 were appropriate for meta-analysis (four 4GC and eight APP). The results showed that carbapenems are associated with a significant reduction in all-cause mortality (relative risk 0.62, 95% confidence interval: 0.41 to 0.95; p=0.03) compared to APP in the treatment of SI, and withdrawals due to adverse events (RR 0.65, 95% CI: 0.45 to 0.96; p=0.03) are also less common. When compared in the treatment of FN, carbapenems are associated with a significant increase in clinical response during the initial 72 h of treatment (RR 1.37, 95% CI: 1.09 to 1.74; p=0.008) and bacteriologic response (RR 1.73, 95% CI: 1.03 to 2.89; p=0.04). For all other outcomes, including all comparisons with 4GC, there were no significant differences between treatments. The use of carbapenems rather than APP could reduce mortality and, by simplifying treatment decisions, reduce the time before patients receive appropriate antibiotic treatment. The currently available evidence is insufficient for distinguishing between carbapenems and 4GC.

  • Reporting of trials presented in conference abstracts needs to be improved.

    26 April 2018

    OBJECTIVES: To assess how trial information reported in conference abstracts differs to their subsequent full publication. METHODS: Randomized trials reported at the American Society of Clinical Oncology conference (1992) were identified. CENTRAL and PubMed (December 2002) were searched to identify corresponding full publications. A checklist (based on CONSORT) was used to compare abstracts for 37 trials with their full publication. RESULTS: Some aspects were well reported. Ninety-five percent of study objectives, 92% of participant eligibility, 100% of trial interventions, and 84% of primary outcomes were the same in both abstract and full publication. Other areas were more discrepant. Forty-six percent reported the same number of participants randomized in the abstract and full publication; only 22% reported the same number analyzed (median number analyzed per trial was 96 for abstracts and 117 for full publications). Eighty-two percent of trials were closed to follow-up in the full publication compared to 19% of abstracts. Lack of information was a major problem in assessing trial quality: no abstracts reported on allocation concealment, 16% reported on blinding and 14% reported intention to treat analysis. These figures were 49, 19, and 46%, respectively, for full publications. CONCLUSION: The information given for trials in conference proceedings can be unstable, especially for trials presenting early or preliminary results, and needs to be improved.

  • Cholesterol

    21 June 2016

    Blood lipids are a major cause of cardiovascular disease (CVD). Higher levels of LDL cholesterol and lower levels of HDL cholesterol are associated with higher heart disease risk. While this has been known for some time, it is only in recent decades that effective treatments to substantially lower LDL cholesterol have become available.

  • Smoking

    21 June 2016

    The link between smoking and lung cancer was originally discovered by Sir Richard Doll in 1956. Co-director Sir Richard Peto has continued to study the impact of tobacco of global health (see video below). Smoking cigarettes is a leading cause of premature death worldwide. There were about 100 million deaths from tobacco in the 20th century, most in developed countries. If current smoking patterns persist, it is estimated that tobacco will kill about 1 billion people this century, mostly in low- and middle-income countries, and about half of these deaths will occur before age 70.

  • Diabetes Mellitus

    21 June 2016

    Diabetes Mellitus is a group of metabolic disorders in which there are high blood sugars over a prolonged period. Rates of type-2 (or adult onset) diabetes have increased rapidly in recent decades due to changes in diet and other lifestyle factors. Patients with diabetes are at increased risk of a number of diseases, most notably cardiovascular disease, kidney disease and damage to the eyes.

  • Other Chronic Diseases

    21 June 2016

    Chronic disease is responsible for a major part of our society’s burden of disability. In addition to our research into chronic diseases such as cancer, cardiovascular disease, diabetes and renal disease we conduct a range of research into other diseases, as well as into the care of people with chronic conditions.