Hallym University

About: Hallym University is a education organization based out in Chuncheon, South Korea. It is known for research contribution in the topics: Population & Medicine. The organization has 10605 authors who have published 18891 publications receiving 302498 citations.

Cost-of-illness studies: concepts, scopes, and methods.

Abstract: Liver diseases are one of the main causes of death, and their ever-increasing prevalence is threatening to cause significant damage both to individuals and society as a whole. This damage is especially serious for the economically active population in Korea. From the societal perspective, it is therefore necessary to consider the economic impacts associated with liver diseases, and identify interventions that can reduce the burden of these diseases. The cost-of-illness study is considered to be an essential evaluation technique in health care. By measuring and comparing the economic burdens of diseases to society, such studies can help health-care decision-makers to set up and prioritize health-care policies and interventions. Using economic theories, this paper introduces various study methods that are generally applicable to most disease cases for estimating the costs of illness associated with mortality, morbidity, disability, and other disease characteristics. It also presents concepts and scopes of costs along with different cost categories from different research perspectives in cost estimations. By discussing the epidemiological and economic grounds of the cost-of-illness study, the reported results represent useful information about several evaluation techniques at an advanced level, such as cost-benefit analysis, cost-effectiveness analysis, and cost-utility analysis.

Duration of Dual Antiplatelet Therapy after Implantation of Drug-Eluting Stents

Abstract: Background The potential benefits and risks of the use of dual antiplatelet therapy beyond a 12-month period in patients receiving drug-eluting stents have not been clearly established. Methods In two trials, we randomly assigned a total of 2701 patients who had received drugeluting stents and had been free of major adverse cardiac or cerebrovascular events and major bleeding for a period of at least 12 months to receive clopidogrel plus aspirin or aspirin alone. The primary end point was a composite of myocardial infarction or death from cardiac causes. Data from the two trials were merged for analysis. Results The median duration of follow-up was 19.2 months. The cumulative risk of the primary outcome at 2 years was 1.8% with dual antiplatelet therapy, as compared with 1.2% with aspirin monotherapy (hazard ratio, 1.65; 95% confidence interval [CI], 0.80 to 3.36; P = 0.17). The individual risks of myocardial infarction, stroke, stent thrombosis, need for repeat revascularization, major bleeding, and death from any cause did not differ significantly between the two groups. However, in the dual-therapy group as compared with the aspirin-alone group, there was a nonsignificant increase in the composite risk of myocardial infarction, stroke, or death from any cause (hazard ratio, 1.73; 95% CI, 0.99 to 3.00; P = 0.051) and in the composite risk of myocardial infarction, stroke, or death from cardiac causes (hazard ratio, 1.84; 95% CI, 0.99 to 3.45; P = 0.06). CONCLUSIONS The use of dual antiplatelet therapy for a period longer than 12 months in patients who had received drug-eluting stents was not significantly more effective than aspirin monotherapy in reducing the rate of myocardial infarction or death from cardiac causes. These findings should be confirmed or refuted through larger, randomized clinical trials with longer-term follow-up. (ClinicalTrials.gov numbers, NCT00484926 and NCT00590174.)

Sample Size and Statistical Power Calculation in Genetic Association Studies

Abstract: A sample size with sufficient statistical power is critical to the success of genetic association studies to detect causal genes of human complex diseases. Genome-wide association studies require much larger sample sizes to achieve an adequate statistical power. We estimated the statistical power with increasing numbers of markers analyzed and compared the sample sizes that were required in case-control studies and case-parent studies. We computed the effective sample size and statistical power using Genetic Power Calculator. An analysis using a larger number of markers requires a larger sample size. Testing a single-nucleotide polymorphism (SNP) marker requires 248 cases, while testing 500,000 SNPs and 1 million markers requires 1,206 cases and 1,255 cases, respectively, under the assumption of an odds ratio of 2, 5% disease prevalence, 5% minor allele frequency, complete linkage disequilibrium (LD), 1:1 case/control ratio, and a 5% error rate in an allelic test. Under a dominant model, a smaller sample size is required to achieve 80% power than other genetic models. We found that a much lower sample size was required with a strong effect size, common SNP, and increased LD. In addition, studying a common disease in a case-control study of a 1:4 case-control ratio is one way to achieve higher statistical power. We also found that case-parent studies require more samples than case-control studies. Although we have not covered all plausible cases in study design, the estimates of sample size and statistical power computed under various assumptions in this study may be useful to determine the sample size in designing a population-based genetic association study.

Loss-of-function mutations in SLC30A8 protect against type 2 diabetes

Abstract: Loss-of-function mutations protective against human disease provide in vivo validation of therapeutic targets, but none have yet been described for type 2 diabetes (T2D). Through sequencing or genotyping of ~150,000 individuals across 5 ancestry groups, we identified 12 rare protein-truncating variants in SLC30A8, which encodes an islet zinc transporter (ZnT8) and harbors a common variant (p.Trp325Arg) associated with T2D risk and glucose and proinsulin levels. Collectively, carriers of protein-truncating variants had 65% reduced T2D risk (P = 1.7 × 10(-6)), and non-diabetic Icelandic carriers of a frameshift variant (p.Lys34Serfs*50) demonstrated reduced glucose levels (-0.17 s.d., P = 4.6 × 10(-4)). The two most common protein-truncating variants (p.Arg138* and p.Lys34Serfs*50) individually associate with T2D protection and encode unstable ZnT8 proteins. Previous functional study of SLC30A8 suggested that reduced zinc transport increases T2D risk, and phenotypic heterogeneity was observed in mouse Slc30a8 knockouts. In contrast, loss-of-function mutations in humans provide strong evidence that SLC30A8 haploinsufficiency protects against T2D, suggesting ZnT8 inhibition as a therapeutic strategy in T2D prevention.