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Background: In May 2007 Nissen and Wolski reported the results of a meta-analysis showing an association between use of rosiglitazone and increased risk of myocardial infarction (N Engl J Med 2007;356(24):2457-2471). Rosiglitazone is an insulin-sensitizing agent used to control blood glucose levels in patients with type 2 diabetes. Subsequent analyses provided evidence that the meta-analysis led to a decline in new and prevalent use of rosiglitazone. We sought to evaluate the impact of the meta-analysis on patterns of use of glucose-lowering drugs and patterns of initiation, cessation and switching of drug therapy, and to estimate these effects in relation to other predictors of initiation and cessation of rosiglitazone.

Methods: We used an interrupted time series analysis to test the impact of the meta-analysis on monthly utilization of glucose-lowering drugs for the 4.3 million residents of the province of British Columbia. We used multivariate logistic regression with generalized estimating equations to test predictors of initiation and cessation of rosiglitazone, including the influence of microvascular and macrovascular comorbidities, before and after the meta-analysis.

Results: A comparison of predicted and observed utilization for November 2007 showed that use of rosiglitazone declined by 40% (95% confidence interval 39%-42%), whereas use of pioglitazone, insulin and sulfonylureas increased. The presence of macrovascular comorbidities strengthened both the negative impact of the meta-analysis on initiation of rosiglitazone therapy and the positive impact of the meta-analysis on cessation of this drug.

Interpretation: The shift in utilization from rosiglitazone to insulin and sulfonylureas and the modest increase in use of pioglitazone suggest that the latter drug was not embraced as a less harmful alternative to rosiglitazone. Macrovascular comorbidities played a greater role in decisions to start or stop rosiglitazone therapy after the meta-analysis was published.

The Canadian Institutes of Health Research and the Multiple Sclerosis (MS) Society of Canada recently convened an Invitational Panel to consider the scientific evidence linking chronic cerebrospinal venous insufficiency (CCSVI) and MS. The panel supported studies to determine whether CCSVI causes MS, but felt that there is currently so much uncertainty about the relationship between CCSVI and MS that a clinical trial is not indicated at this time. This commentary argues that the decision about whether a clinical trial is warranted must be informed by science, but should be addressed from a broader societal perspective. We suggest that members of the public should be more actively involved in scientifically based, but patient-relevant and emotionally charged issues considered by organizations that fund health research.

Background: Differences in the prevalence of cardiovascular disease and associated risk factors have been noted across ethnic groups both within and between countries. The Canadian population is becoming increasingly diverse because of immigration. Understanding ethnic differences in cardiovascular risk factors is critically important in planning appropriate prevention strategies for the country's rapidly changing population. We sought to examine the prevalence of cardiovascular risk factors in various Canadian ethnic groups.

Methods: We analyzed 3 cross-sectional cycles (for 2000, 2003 and 2005) of the Canadian Community Health Survey of people aged 12 years and older. The surveys were conducted by means of self-reported questionnaires. We used stratified analysis to evaluate the relation between risk factors and ethnicity. The effect of participants' ethnicity on the prevalence of risk factors was estimated by means of logistic regression, with adjustment for differences in age, sex, marital status, education, household income, language spoken, immigration status, residency type (urban or rural), household size, region (province or territory) and chronic diseases (heart disease, stroke, cancer, bronchitis, chronic obstructive pulmonary disease, bowel disease, arthritis, epilepsy, ulcers, thyroid disease and diabetes mellitus).

Results: We included 371 154 individuals in the analysis. Compared with white people, people from visible minorities (i.e., neither white nor Aboriginal) had a lower prevalence of diabetes mellitus (4.5% v. 4.0%), hypertension (14.7% v. 10.8%), smoking (20.4% v. 9.7%) and obesity (defined as body mass index ≥ 30; 14.8% v. 9.7%) but a higher prevalence of physical inactivity (50.3% v. 58.1%). More specifically, after adjustment for sociodemographic characteristics, people from most visible minorities, in comparison with the white population, were less likely to smoke; were more likely to be physically inactive, with the exception of people of Korean, Japanese and Latin ethnicity; and were less likely to be obese, with the exception of people of black, Latin, Arab or West Asian ethnicity. However, relative to white people, hypertension was more prevalent among those of Filipino or South East Asian background (odds ratio [OR] 1.54, 95% confidence interval [CI] 1.23-1.93) and those of black ancestry (OR 1.69, 95% CI 1.43-2.00).

Interpretation: Cardiovascular risk factors vary dramatically by ethnic group. Health professionals should increase their promotion of physical activity among visible minorities and should prioritize the detection and control of diabetes and hypertension during routine contact with patients of visible minorities, particularly those of South Asian, Filipino and black ethnicity.

Background: Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is an acquired immune-mediated inflammatory disorder that targets the myelin sheaths of the peripheral nervous system. Intravenous immunoglobulin (IVIg) is a blood product containing immunoglobulin G pooled from many human donors. In fall 2008, CIDP became an approved indication for IVIg in the United States and Canada.

Objective: To evaluate the clinical effectiveness and safety of IVIg for the treatment of CIDP through a systematic review of published randomized controlled trials.

Methods: We searched the MEDLINE (1996-2009, including in-process and other non-indexed citations), Embase (1996-2009) and other databases through the Ovid interface. We applied a methodological filter to limit retrieval to controlled clinical trials, meta-analyses and systematic reviews, and health technology assessments. Retrieval was limited to studies involving humans, and no language restrictions were employed. We pooled extracted data to estimate the effect size of IVIg treatment based on the random-effects model.

Results: We identified 9 unique randomized controlled trials. Of these, 3 compared IVIg therapy with an active comparator (plasma exchange, plasma exchange using extracorporeal immunoadsorption, oral prednisolone, respectively); the other 6 trials had placebo controls. No incremental benefit was seen in terms of primary outcomes for comparisons of IVIg therapy and an active comparator. Data from 4 of the 6 placebo-controlled trials were included in a meta-analysis. A significant improvement in disability (i.e., reduction in disability score) was found, with a standardized mean difference of 0.65 (95% confidence interval [CI] 0.23 to 1.08) in favour of IVIg. A pooled analysis of the proportion of patients with a response to treatment, as defined by the investigators of each of the trials, resulted in a risk ratio of 2.74 (95% CI 1.80 to 4.15) favouring IVIg.

Interpretation: IVIg therapy was statistically superior to placebo in reducing disability and impairment among patients with CIDP. The effectiveness of IVIg was similar to that of the alternative treatment strategies of plasma exchange and oral prednisolone.

Background: Health care professionals worldwide attend courses and workshops to learn evidence-based medicine (EBM), but evidence regarding the impact of these educational interventions is conflicting and of low methodologic quality and lacks generalizability. Furthermore, little is known about determinants of success. We sought to measure the effect of EBM short courses and workshops on knowledge and to identify course and learner characteristics associated with knowledge acquisition.

Methods: Health care professionals with varying expertise in EBM participated in an international, multicentre before-after study. The intervention consisted of short courses and workshops on EBM offered in diverse settings, formats and intensities. The primary outcome measure was the score on the Berlin Questionnaire, a validated instrument measuring EBM knowledge that the participants completed before and after the course.

Results: A total of 15 centres participated in the study and 420 learners from North America and Europe completed the study. The baseline score across courses was 7.49 points (range 3.97-10.42 points) out of a possible 15 points. The average increase in score was 1.40 points (95% confidence interval 0.48-2.31 points), which corresponded with an effect size of 0.44 standard deviation units. Greater improvement in scores was associated (in order of greatest to least magnitude) with active participation required of the learners, a separate statistics session, fewer topics, less teaching time, fewer learners per tutor, larger overall course size and smaller group size. Clinicians and learners involved in medical publishing improved their score more than other types of learners; administrators and public health professionals improved their score less. Learners who perceived themselves to have an advanced knowledge of EBM and had prior experience as an EBM tutor also showed greater improvement than those who did not.

Interpretation: EBM course organizers who wish to optimize knowledge gain should require learners to actively participate in the course and should consider focusing on a small number of topics, giving particular attention to statistical concepts.