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Seokyung Hahn

Publications and source records attributed to Seokyung Hahn.

11 recordsLinked to original sources
PubMed2006

Irreversible JPEG 2000 compression of abdominal CT for primary interpretation: assessment of visually lossless threshold.

To estimate the visually lossless threshold for Joint Photographic Experts Group (JPEG) 2000 compression of contrast-enhanced abdominal computed tomography (CT) images, 100 images were compressed to four different levels: a reversible (as negative control) and irreversible 5:1, 10:1, and 15:1. By alternately displaying the original and the compressed image on the same monitor, six radiologists independently determined if the compressed image was distinguishable from the original image. For each reader, we compared the proportion of the compressed images being rated distinguishable from the original images between the reversible compression and each of the three irreversible compressions using the exact test for paired proportions. For each reader, the proportion was not significantly different between the reversible (0-1%, 0/100 to 1/100) and irreversible 5:1 compression (0-3%). However, the proportion significantly increased with the irreversible 10:1 (95-99%) and 15:1 compressions (100%) versus reversible compression in all readers (P < 0.001); 100 and 95% of the 5:1 compressed images were rated indistinguishable from the original images by at least five of the six readers and all readers, respectively. Irreversibly 5:1 compressed abdominal CT images are visually lossless and, therefore, potentially acceptable for primary interpretation.

Contrast Media↗
PubMed2006

Randomized trial of a brief physiotherapy intervention compared with usual physiotherapy for neck pain patients: cost-effectiveness analysis.

OBJECTIVES: To assess the cost-effectiveness of brief physiotherapy intervention versus usual physiotherapy management in patients with neck pain of musculoskeletal origin in the community setting. METHODS: A cost-effectiveness analysis was conducted alongside a multicenter pragmatic randomized controlled clinical trial. Individuals 18 years of age and older with neck pain of more than 2 weeks were recruited from physiotherapy departments with referrals from general practitioners (GPs) in the East Yorkshire and North Lincolnshire regions in the United Kingdom. A total of 139 patients were allocated to the brief intervention, and 129 to the usual physiotherapy. Resource use data were prospectively collected on the number of physiotherapy sessions, hospital stay, specialist, and GP visits. Quality-adjusted life years (QALYs) were estimated using EQ-5D data collected at baseline, 3 and 12 months from the start of the treatment. The economic evaluation was conducted from the U.K. National Health System perspective. RESULTS: On average, brief intervention produced lower costs (pounds--68; 95 percent confidence interval [CI], pounds--103 to pounds--35) and marginally lower QALYs (-0.001; 95 percent CI, -0.030 to 0.028) compared with usual physiotherapy, resulting in an incremental cost per QALY of pounds 68,000 for usual physiotherapy. These results are sensitive to patients' treatment preferences. CONCLUSIONS: Usual physiotherapy may not be good value for money for the average individual in this trial but could be a cost-effective strategy for those who are indifferent toward which treatment they receive.

Cost-Benefit Analysis↗
PubMed2006

A systematic review of the effects of calcium supplementation on body weight.

Animal studies and epidemiological studies have suggested that Ca supplementation (with Ca supplements or dairy products) may be associated with weight loss in human adults. We aimed to assess whether any association was present by reviewing relevant randomized controlled trials in human subjects. The study was a systematic review and subsequent meta-analysis of randomized controlled trials that used Ca supplementation as an intervention in persons 18 or more years of age, and that reported body weight as a final outcome. A total of thirteen randomized controlled trials were included in the meta-analysis. There was no association between the increased consumption of either Ca supplements or dairy products and weight loss after adjusting for differences in baseline weights between the control and intervention groups (P=0.19 and 0.85, respectively). We therefore concluded that Ca supplementation has no statistically significant association with a reduction in body weight.

Adult↗
PubMed2006

Computed tomography diagnosis of acute appendicitis: advantages of reviewing thin-section datasets using sliding slab average intensity projection technique.

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.

Acute Disease↗
PubMed2005

Prognostic implication of aberrant promoter hypermethylation of CpG islands in adenocarcinoma of the lung.

OBJECTIVES: DNA hypermethylation in promoter regions has been studied for various types of cancer. However, there is no clear evidence that shows whether methylation status can predict long-term survival in patients with lung cancer. METHODS: We collected tissues from 72 patients with lung adenocarcinomas. The cancer and normal lung tissues were tested for DNA hypermethylation by using methylation-specific polymerase chain reaction. The genes investigated were p16INK4alpha(p16), retinoic acid receptor beta-promoter (RARbetaP2), death-associated protein kinase (DAPK), O6-methylguanine-DNA-methyltransferase (MGMT), and glutathione-S-transferase P1 (GSTP1). The status of the DNA methylation was analyzed, and we focused on long-term outcomes, as well as other clinical variables. RESULTS: DNA hypermethylation was observed in 83% for p16, 63% for RARbetaP2, 32% for DAPK, 17% for MGMT, and 46% for GSTP1 from the cancer tissue. From normal lung tissue, the results of methylation were positive in 75% for p16, 24% for RARbetaP2, 10% for DAPK, 6% for MGMT, and 33% for GSTP1. During the mean follow-up period of 18 +/- 11 months (1-40 months), 25 (35%) patients experienced recurrence, and 13 died. In multivariable analysis, old age (>60 years, P = .007), male sex (P = .004), unmethylation of DAPK from cancer tissue (P = .045), and hypermethylation of RARbetaP2 from normal tissue (P = .000) were risk factors for poor survival. Pathologic stage (P = .023), unmethylation of DAPK from normal tissue (P = .043), and hypermethylation of RARbetaP2 from normal tissue (P = .030) were risk factors for disease-free survival. CONCLUSIONS: DNA methylation status of CpG islands seems to be a useful predictor of long-term outcome for adenocarcinoma of the lung. However, because the predictive power is still low, further studies, including those with multiple genes, are necessary to increase its usefulness in the clinical setting.

Adenocarcinoma↗
PubMed2005

Acupuncture for tinnitus: a series of six n = 1 controlled trials.

OBJECTIVE: To explore patient perceived benefits of acupuncture for tinnitus. DESIGN: Controlled n=1 trials, with two phases A and B. SUBJECTS: Six patients with tinnitus. OUTCOME MEASURES: Primary outcome was Daily Diary records related to four tinnitus symptoms: loudness of tinnitus; pitch of tinnitus; waking hours affected with tinnitus; quality of sleep. Secondary outcomes were the Tinnitus Handicap Inventory (THI) and Measure Your Medical Outcome Profile (MYMOP). METHODS: Patients received a course of 10 acupuncture treatments over a 2-week period. Daily Diary entries related to the four tinnitus symptoms were recorded by patients for 14 days pre-treatment (phase A) and 14 days post-treatment (phase B). A hierarchical Bayesian model was used to combine the results from the individual patients to obtain estimates of the population and individual patient treatment effects, incorporating random variations at both levels (between patients and within patient). Tinnitus Handicap Inventory (THI) and Measure Your Medical Outcome Profile (MYMOP) were recorded at assessment points pre-treatment and post-treatment. RESULTS: Six patients participated in the trials, each receiving 10 treatments and completing all Daily Diary entries and outcome measures. For the of symptoms of loudness and pitch, there were variable treatment effects between patients, with a trend for the median overall reduction for loudness of -2.49 (-5.04, 0.02) and for pitch -1.39 (-3.74, 0.89), 95% credibility intervals being shown in brackets. For the other two symptoms, the waking hours affected and quality of sleep, patients' responses were more consistent, with amore credible overall median reduction for affected waking hours of -2.76 (-3.94, -1.63) and for quality of sleep -2.72 (-3.45, -2.03). The THI and MYMOP measures showed a trend of improvement after treatment. CONCLUSION: The n=1 trial methodology, with an AB design and Bayesian analysis, can be considered of value in exploring treatment effects for small numbers of patients receiving individualised treatments, as is common within complementary medicine. When the treatment effects from six patients were synthesized, the results of this study suggest that acupuncture may have a beneficial role in the treatment of tinnitus.

Acupuncture Therapy↗
PubMed2005

Methodological bias in cluster randomised trials.

BACKGROUND: Cluster randomised trials can be susceptible to a range of methodological problems. These problems are not commonly recognised by many researchers. In this paper we discuss the issues that can lead to bias in cluster trials. METHODS: We used a sample of cluster randomised trials from a recent review and from a systematic review of hip protectors. We compared the mean age of participants between intervention groups in a sample of 'good' cluster trials with a sample of potentially biased trials. We also compared the effect sizes, in a funnel plot, between hip protector trials that used individual randomisation compared with those that used cluster randomisation. RESULTS: There is a tendency for cluster trials, with evidence methodological biases, to also show an age imbalance between treatment groups. In a funnel plot we show that all cluster trials show a large positive effect of hip protectors whilst individually randomised trials show a range of positive and negative effects, suggesting that cluster trials may be producing a biased estimate of effect. CONCLUSION: Methodological biases in the design and execution of cluster randomised trials is frequent. Some of these biases associated with the use of cluster designs can be avoided through careful attention to the design of cluster trials. Firstly, if possible, individual allocation should be used. Secondly, if cluster allocation is required, then ideally participants should be identified before random allocation of the clusters. Third, if prior identification is not possible, then an independent recruiter should be used to recruit participants.

Age Factors↗
PubMed2004

Randomised trial of a brief physiotherapy intervention compared with usual physiotherapy for neck pain patients: outcomes and patients' preference.

OBJECTIVES: Firstly, to compare the effectiveness of a brief physiotherapy intervention with "usual" physiotherapy for patients with neck pain. Secondly, to evaluate the effect of patients' preferences on outcome. DESIGN: Non-inferiority randomised controlled trial eliciting preferences independently of randomisation. SETTING: Physiotherapy departments in a community setting in Yorkshire and north Lincolnshire. PARTICIPANTS: 268 patients (mean age 48 years) with subacute and chronic neck pain, who were referred by their general practitioner and randomly assigned to a brief physiotherapy intervention (one to three sessions) using cognitive behaviour principles to encourage self management and return to normal function or usual physiotherapy, at the discretion of the physiotherapist concerned. MAIN OUTCOME MEASURES: The Northwick Park neck pain questionnaire (NPQ), a specific measure of functional disability resulting from neck pain. Also, the short form 36 (SF-36) questionnaire, a generic, health related, quality of life measure; and the Tampa scale for kinesophobia, a measure of fear and avoidance of movement. RESULTS: At 12 months, patients allocated to usual physiotherapy had a small but significant improvement in NPQ scores compared with patients in the brief intervention group (mean difference 1.99, 95% confidence interval 0.45 to 3.52; P = 0.01). Although the result shows a significant inferiority of the intervention, the confidence interval shows that the effect could be in the non-inferiority range for the brief intervention (below 1.2 points of NPQ score). Patients who preferred the brief intervention and received this treatment had similar outcomes to patients receiving usual physiotherapy. CONCLUSIONS: Usual physiotherapy may be only marginally better than a brief physiotherapy intervention for neck pain. Patients with a preference for the brief intervention may do at least as well with this approach. Additional training for the physiotherapists in cognitive behaviour techniques might improve this approach further.

Adolescent↗
PubMed2003

An illustration of the modelling of cost and efficacy data from a clinical trial.

Health care providers, purchasers and policy makers need to make informed decisions regarding the provision of cost-effective care. When a new health care intervention is to be compared with the current standard, an economic evaluation alongside an evaluation of health benefits provides useful information for the decision making process. We consider the information on cost-effectiveness which arises from an individual clinical trial comparing the two interventions. Recent methods for conducting a cost-effectiveness analysis for a clinical trial have focused on the net benefit parameter. The net benefit parameter, a function of costs and health benefits, is positive if the new intervention is cost-effective compared with the standard. In this paper we describe frequentist and Bayesian approaches to cost-effectiveness analysis which have been suggested in the literature and apply them to data from a clinical trial comparing laparoscopic surgery with open mesh surgery for the repair of inguinal hernias. We extend the Bayesian model to allow the total cost to be divided into a number of different components. The advantages and disadvantages of the different approaches are discussed. In January 2001, NICE issued guidance on the type of surgery to be used for inguinal hernia repair. We discuss our example in the light of this information.

Bayes Theorem↗
PubMedDate not supplied

Added value of coronal reformations for duty radiologists and for referring physicians or surgeons in the CT diagnosis of acute appendicitis.

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.

Acute Disease↗