The use of aspirin for primary prevention of colorectal cancer: a systematic review prepared for the U.S. Preventive Services Task Force.

BACKGROUND: Aspirin for prevention of colorectal cancer is controversial. PURPOSE: To examine the benefits and harms of aspirin chemoprevention. DATA SOURCES: MEDLINE, 1966 to December 2006; EMBASE, 1980 to April 2005; CENTRAL, Cochrane Collaboration's registry of clinical trials; Cochrane Database of Systematic Reviews. STUDY SELECTION: Two independent reviewers conducted multilevel screening to identify randomized, controlled trials (RCTs), case-control studies, and cohort studies of aspirin chemoprophylaxis. For harms, systematic reviews were sought. DATA EXTRACTION: In duplicate, data were abstracted and checked and quality was assessed. DATA SYNTHESIS: Regular use of aspirin reduced the incidence of colonic adenomas in RCTs (relative risk [RR], 0.82 [95% CI, 0.7 to 0.95]), case-control studies (RR, 0.87 [CI, 0.77 to 0.98]), and cohort studies (RR, 0.72 [CI, 0.61 to 0.85]). In cohort studies, regular use of aspirin was associated with RR reductions of 22% for incidence of colorectal cancer. Two RCTs of low-dose aspirin failed to show a protective effect. Data for colorectal cancer mortality were limited. Benefits from chemoprevention were more evident when aspirin was used at a high dose and for periods longer than 10 years. Aspirin use was associated with a dose-related increase in incidence of gastrointestinal complications. LIMITATIONS: Important clinical and methodological heterogeneity in the definitions of regular use, dose, and duration of use of aspirin necessitated careful grouping for analysis. CONCLUSIONS: Aspirin appears to be effective at reducing the incidence of colonic adenoma and colorectal cancer, especially if used in high doses for more than 10 years. However, the possible harms of such a practice require careful consideration. Further evaluation of the cost-effectiveness of chemoprevention compared with, and in combination with, a screening strategy is required.

Nonsteroidal anti-inflammatory drugs and cyclooxygenase-2 inhibitors for primary prevention of colorectal cancer: a systematic review prepared for the U.S. Preventive Services Task Force.

PURPOSE: To examine the benefits and harms of nonaspirin (non-ASA) nonsteroidal anti-inflammatory drugs (NSAIDs) and cyclooxygenase (COX-2) inhibitors for the prevention of colorectal cancer (CRC) and adenoma. DATA SOURCES: MEDLINE (1966 to 2006), EMBASE (1980 to 2006), Cochrane Central Register of Controlled Trials, Cochrane Collaboration's registry of clinical trials, Cochrane Database of Systematic Reviews. STUDY SELECTION: Randomized, controlled trials and case-control and cohort studies of the effectiveness of NSAIDs for the prevention of CRC and colorectal adenoma were identified by multilevel screening by 2 independent reviewers. Systematic reviews of harms were sought. DATA EXTRACTION: Data abstraction, checking, and quality assessment were completed in duplicate. DATA SYNTHESIS: A single cohort study showed no effect of non-ASA NSAIDs on death due to CRC. Colorectal cancer incidence was reduced with non-ASA NSAIDs in cohort studies (relative risk, 0.61 [95% CI, 0.48 to 0.77]) and case-control studies (relative risk, 0.70 [CI, 0.63 to 0.78]). Colorectal adenoma incidence was also reduced with non-ASA NSAID use in cohort studies (relative risk, 0.64 [CI, 0.48 to 0.85]) and case-control studies (relative risk, 0.54 [CI, 0.4 to 0.74]) and by COX-2 inhibitors in randomized, controlled trials (relative risk, 0.72 [CI, 0.68 to 0.77]). The ulcer complication rate associated with non-ASA NSAIDs is 1.5% per year. Compared with non-ASA NSAIDs, COX-2 inhibitors reduce this risk but, in multiyear use, have a higher ulcer complication rate than placebo. Cyclooxygenase-2 inhibitors and nonnaproxen NSAIDs increase the risk for serious cardiovascular events (relative risk, 1.86 [CI, 1.33 to 2.59] for COX-2 inhibitors vs. placebo). LIMITATIONS: Heterogeneity in the dose, duration and frequency of use necessitated careful grouping for analysis. CONCLUSIONS: Cyclooxygenase-2 inhibitors and NSAIDs reduce the incidence of colonic adenomas. Nonsteroidal anti-inflammatory drugs also reduce the incidence of CRC. However, these agents are associated with important cardiovascular events and gastrointestinal harms. The balance of benefits to risk does not favor chemoprevention in average-risk individuals.

Efficacy of omega-3 fatty acids in preventing age-related macular degeneration: a systematic review.

TOPIC: What is the evidence for efficacy of dietary and/or supplemental omega-3 fatty acids in preventing age-related macular degeneration (AMD)? CLINICAL RELEVANCE: Age-related macular degeneraion is the leading cause of blindness and vision impairment in persons older than 50 years living in North America. There is no cure for AMD, and treatment does not usually restore vision but only prevents disease progression to a modest degree. omega-3 fatty acids are considered potentially important antioxidants and are being considered as an arm of the Age-Related Eye Disease Study II clinical trial. METHODS/LITERATURE REVIEWED: Keywords were searched in Medline, Pre-Medline, Embase, and the Cochrane Library on Ovid. There was no restriction on the year or language of publication. RESULTS: There were 6 observational studies found, but the specific outcomes, exposures, and covariates studied all varied greatly. CONCLUSION: There is some clinical evidence for protection of AMD from omega-3 fatty acids. However, the results are not consistent. Hence, our conclusion is that this issue is neither clearly supported nor refuted by the present world literature. This is an intriguing and extremely important question but needs further study first with prospective cohort designs and, if positive, randomized clinical trials.

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

BACKGROUND: Breast 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. METHODS: Ten 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 indicator's scientific validation as a measure was assessed. The American Society of Clinical Oncology (ASCO) was asked to contribute quality measures under development. RESULTS: Sixty 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. CONCLUSION: While some studies revealed patterns of under-use of care, all adherence data require confirmation using validated quality measures. ASCO's 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.

The Argentine-Spanish SF-36 Health Survey was successfully validated for local outcome research.

OBJECTIVE: To evaluate psychometric properties of the Argentine-Spanish SF-36 and to validate the physical component summary (PCS) and mental component summary (MCS) measures. STUDY DESIGN AND SETTING: A self-administration of the SF-36 with 1-year follow-up was performed in a University-based ambulatory center in Buenos Aires. Diagnoses were abstracted from the chart. Univariate analysis, psychometric methods, and confirmatory factor analyses were conducted. RESULTS: Of 3,290 subjects, 2,638 had computable scores and were included: 1,938 at their initial contact and 700 from a random sample of other enrollees. Cronbach's alpha ranged from 0.79 to 0.92 in all subscales except for General Health. Age was related to PCS scores (lower in the elderly) but not to MCS scores. PCS and MCS provided good discrimination among mutually exclusive disease categories; minor medical (52.2 vs. 51.1), psychosocial (48.1 vs. 43.0), chronic medical (46.2 vs. 51.0) and both chronic and mental conditions (44.9 vs. 45.1) in PCS and MCS, respectively (P<0.01). Mean annual doctor visits increased from 3.6 to 5.3 in subjects with PCS>55 and PCS<35, and from 4.4 to 6.0 in subjects with MCS>55 and MCS<35, respectively (P<0.0001). CONCLUSIONS: SF-36 is a valid tool for outcome research in Argentina although normative general population studies are needed.

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 omega-3 fatty acids on eye health, the aim of this report was to appraise and synthesize the evidence for the effects of omega-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 omega-3 fatty acids in slowing down the progression of AMD. The prospective cohort study addressed the question: what is the evidence that omega-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.

Registro de estudios controlados aleatorizados: ¿por qué es tan necesario? / Registry of controlled studies randomized: why it's so necessary?

El presente comentario editorial describe la relevancia ética y científica de promover el registro de estudios controlados aleatorizados. Destaca el problema del sesgo de publicación y como éste podría conducir a conclusiones erróneas, especialmente en el caso de los efectos adversos de las drogas, cuyos resultados demoran, peligrosamente, en darse a conocer. Resalta que la transparencia y colaboración entre los patrocinadores, investigadores y las revistas científicas, son fundamentales para mejorar el avance científico y, en definitiva, brindar una mejor salud a los pacientes.