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.

Drugs for preventing lung cancer in healthy people.

Abstract: BACKGROUND This is the second update of this Cochrane Review. Some studies have suggested a protective effect of antioxidant nutrients and higher dietary levels of fruits and vegetables on lung cancer. OBJECTIVES To determine whether vitamins and minerals and other potential agents, alone or in combination, reduce lung cancer incidence and lung cancer mortality in healthy populations. SEARCH METHODS We searched CENTRAL, MEDLINE and Embase from 1974 to May 2019 and screened references included in published studies and reviews. SELECTION CRITERIA We included randomised controlled trials (RCTs) comparing vitamins or mineral supplements with placebo, administered to healthy people with the aim of preventing lung cancer. DATA COLLECTION AND ANALYSIS Four review authors independently selected the trials to be included in the review, assessed their methodological quality and extracted data. For dichotomous outcomes we calculated risk ratios (RRs) and 95% confidence intervals (CIs) and pooled results using the random-effects model. We assessed the risk of bias using Cochrane's 'Risk of bias' assessment tool and certainty of evidence using the GRADE approach. MAIN RESULTS In this update, we identified three new trials for a total of 12 studies. Six analysed vitamin A, three vitamin C, three combined vitamin D3 + calcium, four vitamin E combined with other products, one selenium supplements and nine studied combinations of two or more products. Four studies included only men and five only women. Vitamin A results in little to no difference in lung cancer incidence (RR 1.09, 95% CI 1.00 to 1.19; 5 RCTs, 212314 participants; high-certainty evidence) and lung cancer mortality (RR 1.06, 95% CI 0.81 to 1.38; 3 RCTs, 190118 participants; high-certainty evidence). But in smokers or asbestos workers vitamin A increases the risk of lung cancer incidence (RR 1.10, 95% CI 1.01 to 1.20; 3 RCTs, 43995 participants; high-certainty evidence), lung cancer mortality (RR 1.18, 95% CI 1.01 to 1.38; 2 RCTs, 29426 participants; high-certainty evidence) and all-cause mortality (RR 1.09, 95% CI 1.05 to 1.13; 2 RCTs, 32883 participants; high-certainty evidence). Vitamin A increases the risk of minor side effects, such as yellowing of the skin and minor gastrointestinal symptoms (high-certainty evidence). Vitamin C likely results in little to no difference in lung cancer incidence (RR 1.29, 95% CI 0.67 to 2.49; 2 RCTs, 14953 participants; moderate-certainty evidence). In women, vitamin C increases the risk of lung cancer incidence (RR 1.84, 95% CI 1.14 to 2.95; 1 RCT, 7627 participants; high-certainty evidence). In men, vitamin C results in little to no difference in mortality for lung cancer (RR 0.81, 95% CI 0.53 to 1.23; 1 RCT, 7326 participants; high-certainty evidence). Vitamin D + calcium may result in little to no difference in lung cancer incidence in postmenopausal women (RR 0.90, 95% CI 0.39 to 2.08; 3 RCTs, 37601 women; low-certainty evidence). Vitamin E results in little to no difference in lung cancer incidence (RR 1.01, 95% CI 0.90 to 1.14; 3 RCTs, 36841 participants; high-certainty evidence) or to lung cancer mortality (RR 0.96, 95% CI 0.77 to 1.18; 2 RCTs, 29214 participants; high-certainty evidence), but increases the risk of haemorrhagic strokes (hazard ratio (HR), 1.74, 95% CI 1.04 to 2.91; 1 RCT, 14641 participants; high-certainty evidence). Calcium results in little to no difference in lung cancer incidence in postmenopausal women (RR 0.65, 95% CI 0.13 to 3.18; 1 RCT, 733 participants) or in risk of renal calculi (RR 1.94, 95% CI 0.20 to 18.57; 1 RCT, 733 participants; low-certainty evidence). Selenium in men results in little to no difference in lung cancer incidence (RR 1.11, 95% CI 0.80 to 1.54; 1 RCT, 17448 participants; high-certainty evidence) and lung cancer mortality (RR 1.09, 95% CI 0.72 to 1.66; 1 RCT, 17448 participants; high-certainty evidence) and increases the risk for grade 1 to 2 dermatitis (RR 1.16, 95% CI 1.04 to 1.31; 1 RCT, 17448 participants; high-certainty evidence) and for alopecia (RR 1.28, 95% CI 1.07 to 1.53; 1 RCT, 17448 participants; high-certainty evidence). The combination of vitamins A, C, E + selenium + zinc results in little to no difference in lung cancer incidence (RR 0.64, 95% CI 0.28 to 1.48; 1 RCT, 12741 participants; high-certainty evidence). AUTHORS' CONCLUSIONS Well-designed RCTs have shown no beneficial effect of supplements for the prevention of lung cancer and lung cancer mortality in healthy people. Vitamin A supplements increase lung cancer incidence and mortality in smokers or persons exposed to asbestos. Vitamin C increases lung cancer incidence in women. Vitamin E increases the risk of haemorrhagic strokes.

House dust mite control measures for asthma: systematic review

Abstract: The major allergen in house dust comes from mites. We performed a systematic review of the randomized trials that had assessed the effects of reducing exposure to house dust mite antigens in the homes of people with mite-sensitive asthma, and had compared active interventions with placebo or no treatment. Fifty-four trials (3002 patients) were included. Thirty-six trials assessed physical methods (26 mattress covers), 10 chemical methods and eight a combination of chemical and physical methods. Despite the fact that many trials were of poor quality and would be expected to exaggerate the reported effect, we did not find an effect of the interventions. For the most frequently reported outcome, peak flow in the morning (1565 patients), the standardized mean difference was 0.00 (95% confidence interval (CI) -0.10 to 0.10). There were no statistically significant differences in number of patients improved (relative risk 1.01, 95% CI 0.80-1.27), asthma symptom scores (standardized mean difference -0.04, 95% CI -0.15 to 0.07) or in medication usage (standardized mean difference -0.06, 95% CI -0.18 to 0.07). Chemical and physical methods aimed at reducing exposure to house dust mite allergens cannot be recommended.

Erythropoietin or Darbepoetin for patients with cancer--meta-analysis based on individual patient data.

Abstract: BACKGROUND: Erythropoiesis-stimulating agents (ESAs) reduce anemia in cancer patients and may improve quality of life, but there are concerns that ESAs might increase mortality OBJECTIVES: Our objectives were to examine the effect of ESAs and identify factors that modify the effects of ESAs on overall survival, progression free survival, thromboembolic and cardiovascular events as well as need for transfusions and other important safety and efficacy outcomes in cancer patients SEARCH STRATEGY: We searched the Cochrane Library, Medline, Embase and conference proceedings for eligible trials Manufacturers of ESAs were contacted to identify additional trials SELECTION CRITERIA: We included randomized controlled trials comparing epoetin or darbepoetin plus red blood cell transfusions (as necessary) versus red blood cell transfusions (as necessary) alone, to prevent or treat anemia in adult or pediatric cancer patients with or without concurrent antineoplastic therapy DATA COLLECTION AND ANALYSIS: We performed a meta-analysis of randomized controlled trials comparing epoetin alpha, epoetin beta or darbepoetin alpha plus red blood cell transfusions versus transfusion alone, for prophylaxis or therapy of anemia while or after receiving anti-cancer treatment Patient-level data were obtained and analyzed by independent statisticians at two academic departments, using fixed-effects and random-effects meta-analysis Analyses were according to the intention-to-treat principle Primary endpoints were on study mortality and overall survival during the longest available follow-up, regardless of anticancer treatment, and in patients receiving chemotherapy Tests for interactions were used to identify differences in effects of ESAs on mortality across pre-specified subgroups The present review reports only the results for the primary endpoint MAIN RESULTS: A total of 13933 cancer patients from 53 trials were analyzed, 1530 patients died on-study and 4993 overall ESAs increased on study mortality (combined hazard ratio [cHR] 117; 95% CI 106-130) and worsened overall survival (cHR 106; 95% CI 100-112), with little heterogeneity between trials (I(2) 0%, p=087 and I(2) 71%, p=033, respectively) Thirty-eight trials enrolled 10441 patients receiving chemotherapy The cHR for on study mortality was 110 (95% CI 098-124) and 104; 95% CI 097-111) for overall survival There was little evidence for a difference between trials of patients receiving different cancer treatments (P for interaction=042) AUTHORS' CONCLUSIONS: ESA treatment in cancer patients increased on study mortality and worsened overall survival For patients undergoing chemotherapy the increase was less pronounced, but an adverse effect could not be excluded

Gestational Diabetes Mellitus and Diet: A Systematic Review and Meta-analysis of Randomized Controlled Trials Examining the Impact of Modified Dietary Interventions on Maternal Glucose Control and Neonatal Birth Weight

Abstract: OBJECTIVE Medical nutrition therapy is a mainstay of gestational diabetes mellitus (GDM) treatment. However, data are limited regarding the optimal diet for achieving euglycemia and improved perinatal outcomes. This study aims to investigate whether modified dietary interventions are associated with improved glycemia and/or improved birth weight outcomes in women with GDM when compared with control dietary interventions. RESEARCH DESIGN AND METHODS Data from published randomized controlled trials that reported on dietary components, maternal glycemia, and birth weight were gathered from 12 databases. Data were extracted in duplicate using prespecified forms. RESULTS From 2,269 records screened, 18 randomized controlled trials involving 1,151 women were included. Pooled analysis demonstrated that for modified dietary interventions when compared with control subjects, there was a larger decrease in fasting and postprandial glucose (−4.07 mg/dL [95% CI −7.58, −0.57]; P = 0.02 and −7.78 mg/dL [95% CI −12.27, −3.29]; P = 0.0007, respectively) and a lower need for medication treatment (relative risk 0.65 [95% CI 0.47, 0.88]; P = 0.006). For neonatal outcomes, analysis of 16 randomized controlled trials including 841 participants showed that modified dietary interventions were associated with lower infant birth weight (−170.62 g [95% CI −333.64, −7.60]; P = 0.04) and less macrosomia (relative risk 0.49 [95% CI 0.27, 0.88]; P = 0.02). The quality of evidence for these outcomes was low to very low. Baseline differences between groups in postprandial glucose may have influenced glucose-related outcomes. As well, relatively small numbers of study participants limit between-diet comparison. CONCLUSIONS Modified dietary interventions favorably influenced outcomes related to maternal glycemia and birth weight. This indicates that there is room for improvement in usual dietary advice for women with GDM.

Publishing protocols of systematic reviews: comparing what was done to what was planned.

Abstract: ContextPublication of research protocols minimizes bias by explicitly stating a priori hypotheses and methods without prior knowledge of results.MethodsWe conducted a retrospective comparative study to assess the extent to which the content of published Cochrane reviews had changed compared with their previously published protocols and to assess any potential impact these changes may have had in introducing bias to the study. We identified previously published protocols for new Cochrane reviews appearing in The Cochrane Library; 2000, issue 3. The texts of published protocols and completed reviews were compared. Two raters independently identified changes to the different sections of the protocol and classified the changes as none, minor, or major.ResultsOf the 66 new Cochrane reviews, we identified a previously published protocol for 47 reviews. Of these, 43 reviews had at least 1 section that had undergone a major change compared with the most recently published protocol. The greatest variation between protocols and reviews was in the methods section, in which 68% of reviews (n = 32) had undergone a major change. Changes made in other sections that may have resulted in the introduction of bias included narrowing of objectives, addition of comparisons or new outcome measures, broadening of criteria for the types of study design included, and narrowing of types of participants included.ConclusionsResearch protocols, even if published, are likely to remain, at least to some extent, iterative documents. We found that a large number of changes were made to Cochrane reviews, some of which could be prone to influence by prior knowledge of results. Even if many of the changes between protocol and review improve the overall study, the reasons for making these should be clearly identified and documented within the final review.