Isolde Sommer

Socioeconomic inequalities in non-communicable diseases and their risk factors: an overview of systematic reviews

BackgroundNon-communicable diseases (NCDs) are the largest cause of premature death worldwide. Socioeconomic inequalities contribute to a disparity in the burden of NCDs among disadvantaged and advantaged populations in low (LIC), middle (MIC), and high income countries (HIC). We conducted an overview of systematic reviews to systematically and objectively assess the available evidence on socioeconomic inequalities in relation to morbidity and mortality of NCDs and their risk factors.MethodsWe searched PubMed, The Cochrane Library, EMBASE, SCOPUS, Global Health, and Business Source Complete for relevant systematic reviews published between 2003 and December 2013. Two authors independently screened abstracts and full-text publications and determined the risk of bias of the included systematic reviews.ResultsWe screened 3302 abstracts, 173 full-text publications and ultimately included 22 systematic reviews. Most reviews had major methodological shortcomings; however, our synthesis showed that having low socioeconomic status (SES) and/or living in low and middle income countries (LMIC) increased the risk of developing cardiovascular diseases (CVD), lung and gastric cancer, type 2 diabetes, and chronic obstructive pulmonary disease (COPD). Furthermore, low SES increased the risk of mortality from lung cancer, COPD, and reduced breast cancer survival in HIC. Reviews included here indicated that lower SES is a risk factor for obesity in HIC, but this association varied by SES measure. Early case fatalities of stroke were lower and survival of retinoblastoma was higher in MIC compared to LIC.ConclusionsThe current evidence supports an association between socioeconomic inequalities and NCDs and risk factors for NCDs. However, this evidence is incomplete and limited by the fairly low methodological quality of the systematic reviews, including shortcomings in the study selection and quality assessment process.

Taxation of sugar‐sweetened beverages for reducing their consumption and preventing obesity or other adverse health outcomes

This is the protocol for a review and there is no abstract. The objectives are as follows: To assess the effects of taxation of sugar-sweetened beverages (SSBs) on SSB consumption, energy intake, overweight, obesity, and other adverse health outcomes in the general population.

Grades for quality of evidence were associated with distinct likelihoods that treatment effects will remain stable

OBJECTIVES We sought to determine whether producers or users of systematic reviews using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach or a close variation give the same meanings to terms intended to convey uncertainty about treatment effects when interpreting grades for the quality or strength of evidence. STUDY DESIGN AND SETTING Following exploratory interviews with stakeholders and user testing, we conducted an international Web-based survey among producers and users of systematic reviews. For each quality grade (high, moderate, low, very low/insufficient), we asked participants to assign a minimum likelihood that treatment effects will not change substantially as new studies emerge. Using multivariate analysis of covariance, we tested whether the estimated likelihoods differed between producers and users. RESULTS In all, 244 participants completed the survey. The associated minimum likelihoods that treatment effects will not change substantially for high, moderate, and low grades of quality of evidence (QOE) were 86% [95% confidence interval (CI): 85%, 87%], 61% (95% CI: 59%, 63%), and 34% (95% CI: 32%, 36%), respectively (very low was preset at 0%). Likelihoods for each grade were similar between producers and users of systematic reviews (P > 0.05 for all comparisons). CONCLUSION GRADE is, in general, a suitable method to convey uncertainties for systematic review producers to users. The wide ranges of likelihoods associated with GRADE terms suggest that current definitions of levels of QOE that rely exclusively on qualitative certainty expressions should be augmented by numerical predictions once such data are available.

Average effect estimates remain similar as evidence evolves from single trials to high-quality bodies of evidence: a meta-epidemiologic study

OBJECTIVES The objective of our study was to use a diverse sample of medical interventions to assess empirically whether first trials rendered substantially different treatment effect estimates than reliable, high-quality bodies of evidence. STUDY DESIGN AND SETTING We used a meta-epidemiologic study design using 100 randomly selected bodies of evidence from Cochrane reports that had been graded as high quality of evidence. To determine the concordance of effect estimates between first and subsequent trials, we applied both quantitative and qualitative approaches. For quantitative assessment, we used Lins concordance correlation and calculated z-scores; to determine the magnitude of differences of treatment effects, we calculated standardized mean differences (SMDs) and ratios of relative risks. We determined qualitative concordance based on a two-tiered approach incorporating changes in statistical significance and magnitude of effect. RESULTS First trials both overestimated and underestimated the true treatment effects in no discernible pattern. Nevertheless, depending on the definition of concordance, effect estimates of first trials were concordant with pooled subsequent studies in at least 33% but up to 50% of comparisons. The pooled magnitude of change as bodies of evidence advanced from single trials to high-quality bodies of evidence was 0.16 SMD [95% confidence interval (CI): 0.12, 0.21]. In 80% of comparisons, the difference in effect estimates was smaller than 0.5 SMDs. In first trials with large treatment effects (>0.5 SMD), however, estimates of effect substantially changed as new evidence accrued (mean change 0.68 SMD; 95% CI: 0.50, 0.86). CONCLUSION Results of first trials often change, but the magnitude of change, on average, is small. Exceptions are first trials that present large treatment effects, which often dissipate as new evidence accrues.

Effects of lifestyle changes on adults with prediabetes: A systematic review and meta-analysis

AIMS To assess the efficacy, safety, and cost-effectiveness of lifestyle intervention, compared with treatment as usual in people with prediabetes as defined by the American Diabetes Association. For older studies, we used the 1985 World Health Organization definition. METHODS We systematically searched multiple electronic databases and referenced lists of pertinent review articles from January 1980 through November 2015. We performed an update search in MEDLINE on April 26, 2017. Based on a priori established eligibility criteria, we dually reviewed the literature, extracted data, and rated the risk of bias of included studies with validated checklists. To assess the efficacy of lifestyle intervention to prevent or delay further progression to type 2 diabetes, we conducted a random-effects meta-analysis. We assessed the certainty of evidence using the GRADE (Grading of Recommendations Assessment, Development and Evaluation) approach. RESULT Pooled results of 16 randomized controlled trials showed that people with prediabetes who received lifestyle intervention had a lower rate of progression to type 2 diabetes after one (4% vs. 10%, RR 0.46 [CI 0.32, 0.66]) and three years of follow-up (14% vs. 23%, RR 0.64 [95% CI 0.53, 0.77]). The majority of the studies also showed a greater weight loss in lifestyle intervention participants, with a great variation between studies. Costs per quality-adjusted life-year were lower when the benefits of lifestyle intervention were analyzed over a lifelong time horizon compared to only the period of lifestyle intervention (three years) or to modeling over a ten-year period. CONCLUSION Lifestyle intervention is an efficacious, safe, and cost-effective measure to reduce the risk of progression to type 2 diabetes in people diagnosed with prediabetes. More research is necessary to compare the efficacy of various modes, frequencies, and intensities of lifestyle intervention across studies.