Andra Morrison

Treating asthma with omega-3 fatty acids: where is the evidence? A systematic review

BackgroundConsiderable interest exists in the potential therapeutic value of dietary supplementation with the omega-3 fatty acids. Given the interplay between pro-inflammatory omega-6 fatty acids, and the less pro-inflammatory omega-3 fatty acids, it has been thought that the latter could play a key role in treating or preventing asthma. The purpose was to systematically review the scientific-medical literature in order to identify, appraise, and synthesize the evidence for possible treatment effects of omega-3 fatty acids in asthma.MethodsMedline, Premedline, Embase, Cochrane Central Register of Controlled Trials, CAB Health, and, Dissertation Abstracts were searched to April 2003. We included randomized controlled trials (RCTs) of subjects of any age that used any foods or extracts containing omega-3 fatty acids as treatment or prevention for asthma. Data included all asthma related outcomes, potential covariates, characteristics of the study, design, population, intervention/exposure, comparators, and co interventions.ResultsTen RCTs were found pertinent to the present report.ConclusionGiven the largely inconsistent picture within and across respiratory outcomes, it is impossible to determine whether or not omega-3 fatty acids are an efficacious adjuvant or monotherapy for children or adults. Based on this systematic review we recommend a large randomized controlled study of the effects of high-dose encapsulated omega-3 fatty acids on ventilatory and inflammatory measures of asthma controlling diet and other asthma risk factors. This review was limited because Meta-analysis was considered inappropriate due to missing data; poorly or heterogeneously defined populations, interventions, intervention-comparator combinations, and outcomes. In addition, small sample sizes made it impossible to meaningfully assess the impact on clinical outcomes of co-variables. Last, few significant effects were found.

Many quality measurements, but few quality measures assessing the quality of breast cancer care in women: A systematic review

BackgroundBreast cancer in women is increasingly frequent, and care is complex, onerous and expensive, all of which lend urgency to improvements in care. Quality measurement is essential to monitor effectiveness and to guide improvements in healthcare.MethodsTen databases, including Medline, were searched electronically to identify measures assessing the quality of breast cancer care in women (diagnosis, treatment, followup, documentation of care). Eligible studies measured adherence to standards of breast cancer care in women diagnosed with, or in treatment for, any histological type of adenocarcinoma of the breast. Reference lists of studies, review articles, web sites, and files of experts were searched manually. Evidence appraisal entailed dual independent assessments of data (e.g., indicators used in quality measurement). The extent of each quality indicators scientific validation as a measure was assessed. The American Society of Clinical Oncology (ASCO) was asked to contribute quality measures under development.ResultsSixty relevant reports identified 58 studies with 143 indicators assessing adherence to quality breast cancer care. A paucity of validated indicators (n = 12), most of which assessed quality of life, only permitted a qualitative data synthesis. Most quality indicators evaluated processes of care.ConclusionWhile some studies revealed patterns of under-use of care, all adherence data require confirmation using validated quality measures. ASCOs current development of a set of quality measures relating to breast cancer care may hold the key to conducting definitive studies.

The evidence for efficacy of omega-3 fatty acids in preventing or slowing the progression of retinitis pigmentosa: a systematic review

BACKGROUND Studies in preterm and term human infants have suggested that a dietary supply of omega-3 fatty acids is essential for optimal visual development. Several basic science studies support the hypothesis that omega-3 fatty acids may be useful therapeutic agents for pathologies of the retina and lens. As part of a systematic review of the effect of omega-3 fatty acids on eye health, the purpose of this study was to conduct a systematic review of the scientific-medical literature to appraise and synthesize the evidence for the effects of omega-3 fatty acids in preventing the development or progression of retinitis pigmentosa. METHODS A comprehensive search was undertaken in MEDLINE, PREMEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, Global Health, and Dissertation Abstracts. Unpublished literature was sought through manual searches of reference lists of included studies and key review articles and from the files of content experts. Searches were not restricted by language of publication, publication type, or study design. Eligibility criteria were applied to screen eligible studies on two levels. Data extraction and quality assessment were performed. RESULTS Six studies published between 1995 and 2004 met eligibility criteria in investigating the question of the possible value of omega-3 fatty acids in slowing the progression of retinitis pigmentosa. Meta-analysis was not performed because there was not enough available information for formal quantitative analysis. INTERPRETATION There are trends in improvement of some retinitis pigmentosa outcomes with omega-3 fatty acids in the higher quality studies. Clinical research is preliminary in this field, however. Accordingly, definitive answers will require significantly more observational and interventional clinical research.

Evidence for the effect of omega-3 fatty acids on progression of age-related macular degeneration: a systematic review.

Background: As part of a larger systematic review on the effect of &ohgr;-3 fatty acids on eye health, the aim of this report was to appraise and synthesize the evidence for the effects of &ohgr;-3 fatty acids in slowing down the progression of age-related macular degeneration (AMD) and/or decreasing the rate of progression to advanced forms of AMD. Methods: A comprehensive search was undertaken in six databases (MEDLINE, PreMEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, CAB Health, and Dissertation Abstracts). Results: Two unique studies, one randomized clinical trial (RCT) and one prospective cohort study, satisfied the eligibility criteria and were included in the review. The RCT reported evidence on the effect of &ohgr;-3 fatty acids in slowing down the progression of AMD. The prospective cohort study addressed the question: what is the evidence that &ohgr;-3 fatty acids decrease the rate of progression to advanced forms of AMD? Conclusions: Clinical research on this topic is scarce. Only two studies were eligible to be included in this review. Although one study result indicated efficacy of preventing AMD progression to its advanced form, this result needs to be duplicated and supported by future research.

Can electronic search engines optimize screening of search results in systematic reviews: an empirical study

BackgroundMost electronic search efforts directed at identifying primary studies for inclusion in systematic reviews rely on the optimal Boolean search features of search interfaces such as DIALOG® and Ovid™. Our objective is to test the ability of an Ultraseek® search engine to rank MEDLINE® records of the included studies of Cochrane reviews within the top half of all the records retrieved by the Boolean MEDLINE search used by the reviewers.MethodsCollections were created using the MEDLINE bibliographic records of included and excluded studies listed in the review and all records retrieved by the MEDLINE search. Records were converted to individual HTML files. Collections of records were indexed and searched through a statistical search engine, Ultraseek, using review-specific search terms. Our data sources, systematic reviews published in the Cochrane library, were included if they reported using at least one phase of the Cochrane Highly Sensitive Search Strategy (HSSS), provided citations for both included and excluded studies and conducted a meta-analysis using a binary outcome measure. Reviews were selected if they yielded between 1000–6000 records when the MEDLINE search strategy was replicated.ResultsNine Cochrane reviews were included. Included studies within the Cochrane reviews were found within the first 500 retrieved studies more often than would be expected by chance. Across all reviews, recall of included studies into the top 500 was 0.70. There was no statistically significant difference in ranking when comparing included studies with just the subset of excluded studies listed as excluded in the published review.ConclusionThe relevance ranking provided by the search engine was better than expected by chance and shows promise for the preliminary evaluation of large results from Boolean searches. A statistical search engine does not appear to be able to make fine discriminations concerning the relevance of bibliographic records that have been pre-screened by systematic reviewers.