Chung-Mo Nam

Effect of Intravascular Ultrasound–Guided vs Angiography-Guided Everolimus-Eluting Stent Implantation: The IVUS-XPL Randomized Clinical Trial

IMPORTANCEnUse of intravascular ultrasound (IVUS) promotes better clinical outcomes for coronary intervention in complex coronary lesions. However, randomized data demonstrating the clinical usefulness of IVUS are limited for lesions treated with drug-eluting stents.nnnOBJECTIVEnTo determine whether the long-term clinical outcomes with IVUS-guided drug-eluting stent implantation are superior to those with angiography-guided implantation in patients with long coronary lesions.nnnDESIGN, SETTING, AND PARTICIPANTSnThe Impact of Intravascular Ultrasound Guidance on Outcomes of Xience Prime Stents in Long Lesions (IVUS-XPL) randomized, multicenter trial was conducted in 1400 patients with long coronary lesions (implanted stent ≥28 mm in length) between October 2010 and July 2014 at 20 centers in Korea.nnnINTERVENTIONSnPatients were randomly assigned to receive IVUS-guided (nu2009=u2009700) or angiography-guided (nu2009=u2009700) everolimus-eluting stent implantation.nnnMAIN OUTCOMES AND MEASURESnPrimary outcome measure was the composite of major adverse cardiac events, including cardiac death, target lesion-related myocardial infarction, or ischemia-driven target lesion revascularization at 1 year, analyzed by intention-to-treat.nnnRESULTSnOne-year follow-up was complete in 1323 patients (94.5%). Major adverse cardiac events at 1 year occurred in 19 patients (2.9%) undergoing IVUS-guided and in 39 patients (5.8%) undergoing angiography-guided stent implantation (absolute difference, -2.97% [95% CI, -5.14% to -0.79%]) (hazard ratio [HR], 0.48 [95% CI, 0.28 to 0.83], Pu2009=u2009.007). The difference was driven by a lower risk of ischemia-driven target lesion revascularization in patients undergoing IVUS-guided (17 [2.5%]) compared with angiography-guided (33 [5.0%]) stent implantation (HR, 0.51 [95% CI, 0.28 to 0.91], Pu2009=u2009.02). Cardiac death and target lesion-related myocardial infarction were not significantly different between the 2 groups. For cardiac death, there were 3 patients (0.4%) in the IVUS-guided group and 5 patients (0.7%) in the angiography-guided group (HR, 0.60 [95% CI, 0.14 to 2.52], Pu2009=u2009.48). Target lesion-related myocardial infarction occurred in 1 patient (0.1%) in the angiography-guided stent implantation group (Pu2009=u2009.32).nnnCONCLUSIONS AND RELEVANCEnAmong patients requiring long coronary stent implantation, the use of IVUS-guided everolimus-eluting stent implantation, compared with angiography-guided stent implantation, resulted in a significantly lower rate of the composite of major adverse cardiac events at 1 year. These differences were primarily due to lower risk of target lesion revascularization.nnnTRIAL REGISTRATIONnclinicaltrials.gov Identifier: NCT01308281.

The ACC/AHA 2013 pooled cohort equations compared to a Korean Risk Prediction Model for atherosclerotic cardiovascular disease

BACKGROUND AND AIMSnTo evaluate the performance of the American College of Cardiology/American Heart Association (ACC/AHA) 2013 Pooled Cohort Equations in the Korean Heart Study (KHS) population and to develop a Korean Risk Prediction Model (KRPM) for atherosclerotic cardiovascular disease (ASCVD) events.nnnMETHODSnThe KHS cohort included 200,010 Korean adults aged 40-79 years who were free from ASCVD at baseline. Discrimination, calibration, and recalibration of the ACC/AHA Equations in predicting 10-year ASCVD risk in the KHS cohort were evaluated. The KRPM was derived using Cox model coefficients, mean risk factor values, and mean incidences from the KHS cohort.nnnRESULTSnIn the discriminatory analysis, the ACC/AHA Equations White and African-American (AA) models moderately distinguished cases from non-cases, and were similar to the KRPM: For men, the area under the receiver operating characteristic curve (AUROCs) were 0.727 (White model), 0.725 (AA model), and 0.741 (KRPM); for women, the corresponding AUROCs were 0.738, 0.739, and 0.745. Absolute 10-year ASCVD risk for men in the KHS cohort was overestimated by 56.5% (White model) and 74.1% (AA model), while the risk for women was underestimated by 27.9% (White model) and overestimated by 29.1% (AA model). Recalibration of the ACC/AHA Equations did not affect discriminatory ability but improved calibration substantially, especially in men in the White model. Of the three ASCVD risk prediction models, the KRPM showed best calibration.nnnCONCLUSIONSnThe ACC/AHA Equations should not be directly applied for ASCVD risk prediction in a Korean population. The KRPM showed best predictive ability for ASCVD risk.

Physical Activity Level and Risk of Death: The Severance Cohort Study

Background Physical activity decreases deaths from cardiovascular disease and other causes; however, it is unclear whether physical activity is associated with cancer incidence and death in Asian populations. Methods Data from 59 636 Koreans aged 30 to 93 years were collected using a questionnaire and medical examination at the Severance Hospital Health Promotion Center between 1994 and 2004. Study participants were followed for a mean duration of 10.3 years. Results In the exercising group, the multivariate Cox proportional hazards model showed a lower risk of cancer death (hazard ratio [HR] = 0.72, 95% CI = 0.62–0.85) in men but not in women. Those who exercised, as compared with those who did not, had lower risks of all-cause death (men: HR = 0.68, 95% CI = 0.60–0.76; women: HR = 0.65, 95% CI = 0.53–0.79) and noncancer death (men: 0.63, 0.53–0.75; women: 0.52, 0.39–0.69). Physical activity was inversely associated with risk of noncancer death among men and women. Conclusions Physical activity was associated with lower risks of cancer death and noncancer death.

Comparison of hepatocellular carcinoma risk between patients treated with glimepiride and gliclazide

Hepatocellular carcinoma (HCC) is among the most common cancers in the world, ranking fifth for men and eighth for women [1]. Age-adjusted incidence rates are high (> 20 per 100,000 men and > 10 per 100,000 women) in Africa and East Asia (including Korea, China and Taiwan), whereas the rates are low (< 5 per 100,000) in the US, Australia and Northern Europe [1,2]. Besides the common risk factors, such as hepatitis B virus (HBV) and hepatitis C virus (HCV) infection, liver cirrhosis (LC) and chronic alcohol abuse [1,2], the importance of obesity and type 2 diabetes mellitus (T2DM) as HCC risk factors has also been proposed [3]. Upon acknowledging the link between T2DM and HCC, many studies have gone on to investigate the effects of antidiabetes medications on incident HCC [4–6]. Metformin may reduce cancer incidence and cancer-related mortality by improving insulin resistance and activating cellular AMPactivated protein kinase [4,5]. However, the findings for thiazolidinedione exposures and HCC are conflicting [5,6]. On the other hand, the insulin secretagogue sulphonylurea has been associated with an increased cancer risk because it promotes insulin secretion [5,6]. Nevertheless, it remains unclear whether there is any difference depending on the type of sulphonylurea. For this reason, the present study has explored the association between two commonly used sulphonylureas (glimepiride and gliclazide) and the development of HCC.

Study on Effects of Population Stratification on Haplotype Trend Test in Case-Control Studies

Population stratification can cause spurious associations between genetic markers and disease locus. In order to handle this population stratification in haplotype-based case-control association studies, we added population indicators as covariates to the haplotype trend regression model proposed by Zaykin et al. (2002). We investigated through simulations how both population stratification and measurement error in the estimation of true population of each individual affect type I error probabilities of the association tests based on both Zaykin et al.s (2002) model and the proposed model. Based on those results, in the situation that there exists population stratification but there is no error in population classification of each individual, our proposed model does satisfy a type I error probability whereas Zaykin et al.s (2002) model does not. However, as the measurement error increases, a type I error probability of our model correspondingly becomes larger than a nominal significance level. It implies that as long as uncertainty in the estimation of true population of each individual still remains, it is nearly impossible to avoid false positive in case-control association studies based on haplotypes.

Comparing Survival Functions with Doubly Interval-Censored Data: An Application to Diabetes Surveyed by Korean Cancer Prevention Study

Two tests were introduced for comparing several survival functions with doubly interval-censored data and illustrated with data surveyed by Korean Cancer Prevention Study (Jee et al., 2005). The test which extended Kim et al. (2006)s test to the doubly interval-censored data has an advantage over Sun (2006)s test in terms of saving computation time because the proposed test only depends on the size of risk set, and also the proposed test is applicable to continuous failure time data as well as discrete failure time data unlike Suns test. Comparing male with female groups on the incubation time of diabetes was highly different and the survival of female group was longer than that of male one. Regardless of gender, the difference in survival functions of four age groups was highly significant with p-value of less than 0.001. This trend was more remarkable for female group than for male one. Simulation results showed that the significance level of both tests was well controlled and the proposed test was better than Suns test in terms of power.