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Understanding noninferiority trials
Hahn, Seokyung The Korean Pediatric Society 2012 Clinical and Experimental Pediatrics (CEP) Vol.55 No.11
Noninferiority trials test whether a new experimental treatment is not unacceptably less efficacious than an active control treatment already in use. With continuous improvements in health technologies, standard care, and clinical outcomes, the incremental benefits of newly developed treatments may be only marginal over existing treatments. Sometimes assigning patients to a placebo is unethical. In such circumstances, there has been increasing emphasis on the use of noninferiority trial designs. Noninferiority trials are more complex to design, conduct, and interpret than typical superiority trials. This paper reviews the concept of noninferiority trials and discusses some important issues related to them.
이경호,김영훈,Seokyung Hahn,Kyung Won Lee,이학종,Tae Jung Kim,강성범,Joong Ho Shin,Byung Joo Park 대한영상의학회 2006 Korean Journal of Radiology Vol.7 No.2
Objective: To assess the added value of coronal reformation for radiologists and for referring physicians or surgeons in the CT diagnosis of acute appendicitis. Materials and Methods: Contrast-enhanced CT was performed using 16- detector-row scanners in 110 patients, 46 of whom had appendicitis. Transverse (5-mm thickness, 4-mm increment), coronal (5-mm thickness, 4-mm increment), and combined transverse and coronal sections were interpreted by four radiologists, two surgeons and two emergency physicians. The area under the receiver operating characteristic curve (Az value), sensitivity, specificity (McNemar test), diagnostic confidence and appendiceal visualization (Wilcoxon signed rank test) were compared. Results: For radiologists, the additional coronal sections tended to increase the Az value (0.972 vs. 0.986, p = 0.076) and pooled sensitivity (92% [95% CI: 88, 96] vs. 96% [93, 99]), and enhanced appendiceal visualization in true-positive cases (p = 0.031). For non-radiologists, no such enhancement was observed, and the confidence for excluding acute appendicitis declined (p = 0.013). Coronal sections alone were inferior to transverse sections for diagnostic confidence as well as appendiceal visualization for each reader group studied (p < 0.05). Conclusion: The added value of coronal reformation is more apparent for radiologists compared to referring physicians or surgeons in the CT diagnosis of acute appendicitis.
Increase in Mortality Rate Following Coprescription of Cisapride and Contraindicated Drugs
Choi, Nam-Kyong,Hahn, Seokyung,Park, Byung-Joo Harvey Whitney Books Company 2007 The Annals of Pharmacotherapy Vol.41 No.4
<P>BACKGROUND: No epidemiologic study, as of this writing, has been published on the use of cisapride with contraindicated drugs and its relation to mortality rates in a population-based setting. OBJECTIVE: To estimate the prevalence of concomitant use of cisapride with contraindicated drugs and evaluate the association between this and the risk of mortality. METHODS: Claims data were obtained from the Health Insurance Review Agency of Korea. The study population consisted of patients younger than 85 years who visited clinics or hospitals in the city of Busan as new users of cisapride between November 1, 2000, and April 30, 2002. The coprescription of cisapride was defined as prescribing cisapride with one or more contraindicated drugs with the same prescription. Nationwide mortality data were also used. The prevalence of coprescribing cisapride was estimated and the association between this and the risk of mortality was assessed by rate ratios (RRs). The RRs were estimated using Cox's regression model with time-dependent covariate, adjusted for age, sex, and comorbidities. RESULTS: A total of 36,865 patients out of 56,012 claims were newly prescribed cisapride; of these, 1175 patients (3.2%) were concomitantly prescribed at least one contraindicated drug, which suggested adjusted mortality RRs of 14.08 (95% CI 7.41 to 26.76) for recent users and 1.33 (95% CI 0.92 to 1.93) for past users of cisapride. CONCLUSIONS: Despite the discontinuation of the drug's commercial marketing, cisapride was still in use in clinics and hospitals in Busan. In many cases, cisapride was co-prescribed with contraindicated drugs, which is associated with increased mortality rates.</P>
Kim, Ryul,Keam, Bhumsuk,Hahn, Seokyung,Ock, Chan-Young,Kim, Miso,Kim, Tae Min,Kim, Dong-Wan,Heo, Dae Seog Elsevier 2019 Clinical lung cancer Vol.20 No.5
<P><B>Abstract</B></P> <P><B>Background</B></P> <P>This study aimed to comprehensively review the available evidence regarding the efficacy of first-line pembrolizumab for advanced/metastatic non–small-cell lung cancer (NSCLC), and to compare pembrolizumab monotherapy versus pembrolizumab plus chemotherapy versus chemotherapy alone.</P> <P><B>Materials and Methods</B></P> <P>A search of the PubMed, EMBASE, and Cochrane Library databases was performed in July 2018, and abstracts from the American Society of Clinical Oncology meetings (2015-2018) were reviewed. Summaries of the results were pooled using a random-effect model to determine the pooled hazard ratio (HR) for progression-free survival (PFS), overall survival (OS), and their 95% confidence intervals (CIs). A network meta-analysis was used to indirectly compare pembrolizumab monotherapy with pembrolizumab plus chemotherapy.</P> <P><B>Results</B></P> <P>A total of 4 relevant phase III trials comprising 2754 patients were identified. Pembrolizumab (with or without chemotherapy) led to significant improvements in OS and PFS, irrespective of the programmed cell death ligand 1 (PD-L1) tumor proportion score (TPS). In particular, for the subgroup with PD-L1 TPS ≥ 50%, the HR of PFS was 0.49 (95% CI, 0.32-0.76; <I>P</I> = .001), and that of OS was 0.57 (95% CI, 0.45-0.73; <I>P</I> < .001). In terms of PFS, pembrolizumab plus chemotherapy was superior to pembrolizumab monotherapy with an HR of PFS 0.52 (95% CI, 0.27-0.99; <I>P</I> = .048) for the subgroup with PD-L1 TPS ≥ 50%.</P> <P><B>Conclusions</B></P> <P>For patients with NSCLC with PD-L1 TPS ≥ 50%, pembrolizumab plus chemotherapy has a better PFS than pembrolizumab monotherapy in this meta-analysis. To confirm this finding, a prospective phase III trial that directly compares the treatments is warranted.</P>
Lee, Kyoung Ho,Kim, Young Hoon,Hahn, Seokyung,Lee, Kyung Won,Kim, Tae Jung,Kang, Sung-Bum,Shin, Joong Ho Lippincott Williams Wilkins, Inc. 2006 Investigative radiology Vol.41 No.7
OBJECTIVES:: We sought to compare sliding slab mode and standard stack mode in the computed tomography (CT) diagnosis of acute appendicitis. MATERIALS AND METHODS:: Contrast-enhanced CT was performed in 85 patients, 35 of whom had appendicitis. Four readers retrospectively reviewed 5-mm thick transverse sections (4-mm increment) using the stack mode and 2-mm thick sections (1-mm increment) with the sliding slab, average intensity projection. The sliding slab mode started with a 5-mm thick transverse slab, but the readers were encouraged to change the viewing angle and the slab thickness. RESULTS:: In sliding slab mode, the readers changed the viewing angle in 89 of 340 observations (24%) and decreased the slab thickness in 26 observations (8%). Although the receiver operating characteristic analysis did not show a significant difference (P = 0.18), the sliding slab mode enhanced the pooled sensitivity (93.6% vs. 98.6%, P = 0.02), specificity (92.0% vs. 97.5%, P = 0.01), and mean confidence for the diagnosis (P < 0.001) or exclusion (P = 0.002) of acute appendicitis; reduced inconclusive interpretations (5.6% vs. 1.8%, P = 0.01); and visualized the appendix more clearly (P < 0.001). CONCLUSIONS:: Compared with the stack mode, the sliding slab mode enhances diagnostic confidence and more clearly visualizes the appendix.
Kim, Bohyoung,Lee, Kyoung Ho,Kim, Kil Joong,Mantiuk, Rafal,Hahn, Seokyung,Kim, Tae Jung,Kim, Young Hoon American Roentgen Ray Society, etc.] 2008 American Journal of Roentgenology Vol.190 No.2
<P>OBJECTIVE: The objective of our study was to determine whether peak signal-to-noise ratio (PSNR) and a perceptual quality metric (High-Dynamic Range Visual Difference Predictor [HDR-VDP]) can predict the presence of perceptible artifacts in Joint Photographic Experts Group (JPEG) 2000-compressed chest CT images. MATERIALS AND METHODS: One hundred chest CT images were compressed to 5:1, 8:1, 10:1, and 15:1. Five radiologists determined if the original and compressed images were identical (negative response) or different (positive response). The correlation between the results for each metric and the number of readers with positive responses was evaluated using Spearman's rank correlation test. Using the pooled readers' responses as the reference standard, we performed receiver operating characteristic (ROC) analysis to determine the cutoff values balancing sensitivity and specificity and yielding 100% sensitivity in each metric. These cutoff values were then used to estimate the visually lossless thresholds for the compressions for the 100 original images, and the accuracy of the estimates of two metrics was compared (McNemar test). RESULTS: The correlation coefficients were -0.918 and 0.925 for PSNR and the HDR-VDP, respectively. The areas under the ROC curves for the two metrics were 0.983 and 0.984, respectively (p = 0.11). The PSNR and HDR-VDP accurately predicted the visually lossless threshold for 69% and 72% of the 100 images (p = 0.68), respectively, at the cutoff values balancing sensitivity and specificity and for 43% and 47% (p = 0.22), respectively, at the cutoff values reaching 100% sensitivity. CONCLUSION: Both metrics are promising in predicting the perceptible compression artifacts and therefore can potentially be used to estimate the visually lossless threshold.</P>
Kim, Young Hoon,Lee, Kyoung Ho,Park, Seong Ho,Kim, Hyung-Ho,Hahn, Seokyung,Park, Do Joong,Lee, Hye Seung Radiological Society of North America 2009 Radiology Vol.250 No.3
<P>PURPOSE: To determine the added value of multiplanar reformation (MPR) images combined with computed tomographic (CT) images in staging of T4 gastric cancers. MATERIALS AND METHODS: The institutional review board approved this retrospective study and waived informed consent. One hundred forty-nine consecutive patients (99 men [age range, 33-85 years; mean age, 63.1 years] and 50 women [age range, 30-85 years; mean age, 57.1 years]; age range, 30-85 years; mean age, 61.1 years) with pathologically and/or surgically confirmed T3 (n = 110) or T4 tumors (n = 39), with invasion of the transverse colon or mesocolon (n = 23), pancreas (n = 16), diaphragm (n = 4), liver (n = 3), and/or spleen (n = 1) were included. Two experienced radiologists independently reviewed 4-mm-thick transverse CT images and, 10 weeks later, reviewed both transverse CT and additional coronal and sagittal MPR images to assess tumor invasion in each of the aforementioned five adjacent organs. Receiver operating characteristic (ROC) analyses and weighted kappa statistics were obtained to evaluate reader performance and agreement in identifying tumor invasion. RESULTS: With addition of MPR images, the area under the ROC curve (AUC) led to a significant increase in the prediction of adjacent organ invasion in per-organ analyses (0.88 vs 0.95 for reader 1 [P = .01], 0.88 vs 0.98 for reader 2 [P < .001]) and identification of T4 tumors in per-patient analyses (0.79 vs 0.91 for reader 1 [P = .006], 0.78 vs 0.96 for reader 2 [P < .001]). In the five analyzed organs, AUC was significantly increased in regard to invasion of the transverse colon or mesocolon and pancreas; separate analysis was not performed for the diaphragm, liver, and spleen because of the small number of true invasions. Interobserver agreement increased in per-organ (kappa = 0.43 vs 0.67) and per-patient (kappa = 0.42 vs 0.62) analyses. CONCLUSION: Adding MPR images to transverse CT images improves the capability for distinguishing T3 from T4 gastric cancer and prediction of adjacent organ invasion. Supplemental material: http://radiology.rsnajnls.org/cgi/content/full/2502071872/DC1.</P>