Angiotensin Receptor Blockers and the Risk of Suspected Drug-Induced Liver Injury: A Retrospective Cohort Study Using Electronic Health Record-Based Common Data Model in South Korea

INTRODUCTION

Angiotensin receptor blockers are widely used antihypertensive drugs in South Korea. In 2021, the Korea Ministry of Food and Drug Safety acknowledged the need for national compensation for a drug-induced liver injury (DILI) after azilsartan use. However, little is known regarding the association between angiotensin receptor blockers and DILI.

OBJECTIVE

We conducted a retrospective cohort study in incident users of angiotensin receptor blockers from a common data model database (1 January, 2017-31 December, 2021) to compare the risk of DILI among specific angiotensin receptor blockers against valsartan.

METHODS

Patients were assigned to treatment groups at cohort entry based on prescribed angiotensin receptor blockers. Drug-induced liver injury was operationally defined using the International DILI Expert Working Group criteria. Cox regression analyses were conducted to derive hazard ratios and the inverse probability of treatment weighting method was applied. All analyses were performed using R.

RESULTS

In total, 229,881 angiotensin receptor blocker users from 20 university hospitals were included. Crude DILI incidence ranged from 15.6 to 82.8 per 1000 person-years in treatment groups, most were cholestatic and of mild severity. Overall, the risk of DILI was significantly lower in olmesartan users than in valsartan users (hazard ratio: 0.73 [95% confidence interval 0.55-0.96]). In monotherapy patients, the risk was significantly higher in azilsartan users than in valsartan users (hazard ratio: 6.55 [95% confidence interval 5.28-8.12]).

CONCLUSIONS

We found a significantly higher risk of suspected DILI in patients receiving azilsartan monotherapy compared with valsartan monotherapy. Our findings emphasize the utility of real-world evidence in advancing our understanding of adverse drug reactions in clinical practice.

MetaLAB-HOI: Template standardization of health outcomes enable massive and accurate detection of adverse drug reactions from electronic health records

PURPOSE

This study aimed to advance the MetaLAB algorithm and verify its performance with multicenter data to effectively detect major adverse drug reactions (ADRs), including drug-induced liver injury.

METHODS

Based on MetaLAB, we created an optimal scenario for detecting ADRs by considering demographic and clinical records. MetaLAB-HOI was developed to identify ADR signals using common model-based multicenter electronic health record (EHR) data from the clinical health outcomes of interest (HOI) template and design for drug-exposed and nonexposed groups. In this study, we calculated the odds ratio of 101 drugs for HOI in Konyang University Hospital, Seoul National University Hospital, Chungbuk National University Hospital, and Seoul National University Bundang Hospital.

RESULTS

The overlapping drugs in four medical centers are amlodipine, aspirin, bisoprolol, carvedilol, clopidogrel, clozapine, digoxin, diltiazem, methotrexate, and rosuvastatin. We developed MetaLAB-HOI, an algorithm that can detect ADRs more efficiently using EHR. We compared the detection results of four medical centers, with drug-induced liver injuries as representative ADRs.

CONCLUSIONS

MetaLAB-HOI's strength lies in fully utilizing the patient's clinical information, such as prescription, procedure, and laboratory results, to detect ADR signals. Considering changes in the patient's condition over time, we created an algorithm based on a scenario that accounted for each drug exposure and onset period supervised by specialists for HOI. We determined that when a template capable of detecting ADR based on clinical evidence is developed and manualized, it can be applied in medical centers for new drugs with insufficient data.

Development and Application of an Active Pharmacovigilance Framework Based on Electronic Healthcare Records from Multiple Centers in Korea

INTRODUCTION

With the availability of retrospective pharmacovigilance data, the common data model (CDM) has been identified as an efficient approach towards anonymized multicenter analysis; however, the establishment of a suitable model for individual medical systems and applications supporting their analysis is a challenge.

OBJECTIVE

The aim of this study was to construct a specialized Korean CDM (K-CDM) for pharmacovigilance systems based on a clinical scenario to detect adverse drug reactions (ADRs).

METHODS

De-identified patient records (n = 5,402,129) from 13 institutions were converted to the K-CDM. From 2005 to 2017, 37,698,535 visits, 39,910,849 conditions, 259,594,727 drug exposures, and 30,176,929 procedures were recorded. The K-CDM, which comprises three layers, is compatible with existing models and is potentially adaptable to extended clinical research. Local codes for electronic medical records (EMRs), including diagnosis, drug prescriptions, and procedures, were mapped using standard vocabulary. Distributed queries based on clinical scenarios were developed and applied to K-CDM through decentralized or distributed networks.

RESULTS

Meta-analysis of drug relative risk ratios from ten institutions revealed that non-steroidal anti-inflammatory drugs (NSAIDs) increased the risk of gastrointestinal hemorrhage by twofold compared with aspirin, and non-vitamin K anticoagulants decreased cerebrovascular bleeding risk by 0.18-fold compared with warfarin.

CONCLUSION

These results are similar to those from previous studies and are conducive for new research, thereby demonstrating the feasibility of K-CDM for pharmacovigilance. However, the low quality of original EMR data, incomplete mapping, and heterogeneity between institutions reduced the validity of the analysis, thus necessitating continuous calibration among researchers, clinicians, and the government.

Adverse drug events leading to emergency department visits: A multicenter observational study in Korea

Adverse drug events are significant causes of emergency department visits. Systematic evaluation of adverse drug events leading to emergency department visits by age is lacking. This multicenter retrospective observational study evaluated the prevalence and features of adverse drug event-related emergency department visits across ages. We reviewed emergency department medical records obtained from three university hospitals between July 2014 and December 2014. The proportion of adverse drug events among total emergency department visits was calculated. The cause, severity, preventability, and causative drug(s) of each adverse drug event were analyzed and compared between age groups (children/adolescents [<18 years], adults [18–64 years], and the elderly [≥65 years]). Of 59,428 emergency department visits, 2,104 (3.5%) were adverse drug event-related. Adverse drug event-related emergency department visits were more likely to be female and older. Multivariate logistic regression analysis revealed that compared to non- adverse drug event-related cases, adverse drug event-related emergency department visitors were more likely to be female (60.6% vs. 53.6%, p<0.001, OR 1.285, 95% CI 1.025–1.603) and older (50.8 ± 24.6 years vs. 37.7 ± 24.4 years, p<0.001, OR 1.892, 95% CI: 1.397–2.297). Comorbidities such as diabetes, chronic kidney disease, chronic liver disease, and malignancies were also significantly associated with adverse drug event-related emergency department visits. Side effects were the most common type of adverse drug events across age groups, although main types differed substantially depending on age. Serious adverse drug events, hospitalizations, and adverse drug event-related deaths occurred more frequently in the elderly than in adults or children/adolescents. The proportion of adverse drug event-related emergency department visits that were preventable was 15.3%. Causative drugs of adverse drug events varied considerably depending on age group. Adverse drug event features differ substantially according to age group. The findings suggest that an age-specific approach should be adopted in the preventive strategies to reduce adverse drug events.

Peripheral blood transcriptomic clusters uncovered immune phenotypes of asthma

BACKGROUND

Transcriptomic analysis has been used to elucidate the complex pathogenesis of heterogeneous disease and may also contribute to identify potential therapeutic targets by delineating the hub genes. This study aimed to investigate whether blood transcriptomic clustering can distinguish clinical and immune phenotypes of asthmatics, and microbiome in asthmatics.

METHODS

Transcriptomic expression of peripheral blood mononuclear cells (PBMCs) from 47 asthmatics and 21 non-asthmatics was measured using RNA sequencing. A hierarchical clustering algorithm was used to classify asthmatics. Differentially expressed genes, clinical phenotypes, immune phenotypes, and microbiome of each transcriptomic cluster were assessed.

RESULTS

In asthmatics, three distinct transcriptomic clusters with numerously different transcriptomic expressions were identified. The proportion of severe asthmatics was highest in cluster 3 as 73.3%, followed by cluster 2 (45.5%) and cluster 1 (28.6%). While cluster 1 represented clinically non-severe T2 asthma, cluster 3 tended to include severe non-T2 asthma. Cluster 2 had features of both T2 and non-T2 asthmatics characterized by the highest serum IgE level and neutrophil-dominant sputum cell population. Compared to non-asthmatics, cluster 1 showed higher CCL23 and IL1RL1 expression while the expression of TREML4 was suppressed in cluster 3. CTSD and ALDH2 showed a significant positive linear relationship across three clusters in the order of cluster 1 to 3. No significant differences in the diversities of lung and gut microbiomes were observed among transcriptomic clusters of asthmatics and non-asthmatics. However, our study has limitations in that small sample size data were analyzed with unmeasured confounding factors and causal relationships or function pathways were not verified.

CONCLUSIONS

Genetic clustering based on the blood transcriptome may provide novel immunological insight, which can be biomarkers of asthma immune phenotypes. Trial registration Retrospectively registered.

Sodium-Glucose Cotransporter-2 Inhibitor-Related Diabetic Ketoacidosis: Accuracy Verification of Operational Definition

BACKGROUND

The most important aspect of a retrospective cohort study is the operational definition (OP) of the disease. We developed a detailed OP for the detection of sodium-glucose cotransporter-2 inhibitors (SGLT2i) related to diabetic ketoacidosis (DKA). The OP was systemically verified and analyzed.

METHODS

All patients prescribed SGLT2i at four university hospitals were enrolled in this experiment. A DKA diagnostic algorithm was created and distributed to each hospital; subsequently, the number of SGLT2i-related DKAs was confirmed. Then, the algorithm functionality was verified through manual chart reviews by an endocrinologist using the same OP.

RESULTS

A total of 8,958 patients were initially prescribed SGLT2i. According to the algorithm, 0.18% (16/8,958) were confirmed to have SGLT2i-related DKA. However, based on manual chart reviews of these 16 cases, there was only one case of SGLT2i-related DKA (positive predictive value = 6.3%). Even after repeatedly narrowing the diagnosis range of the algorithm, the effect of a positive predictive value was insignificant (6.3-10.0%, P > 0.999).

CONCLUSION

Owing to the nature of electronic medical record data, we could not create an algorithm that clearly differentiates SGLT2i-related DKA despite repeated attempts. In all retrospective studies, a portion of the samples should be randomly selected to confirm the accuracy of the OP through chart review. In retrospective cohort studies in which chart review is not possible, it will be difficult to guarantee the reliability of the results.

Percutaneous coronary intervention in patients with peripheral artery disease and adverse cardiovascular adverse event and bleeding

Background

Peripheral artery disease (PAD) increase the risk of comorbidity and mortality in coronary artery disease (CAD).

Objectives

We evaluate influence of PAD on prognosis in patients undergoing percutaneous coronary intervention (PCI).

Methods

We analyzed all consecutive patients included in our dedicated local registry for PCI between January 2011 and December 2016. Presence of PAD was defined by decreased ankle-brachial index (&lt;0.9). Major adverse cardiovascular event (MACE) was defined as a composite of cardiovascular death, non-fatal myocardial infarct, revascularization, and ischemic stroke. Major bleeding was defined as Bleeding Academic Research Consortium 3 or 5.

Results

Among the 4,747 patients who underwent the PCI, 12.9% (n=610) of PAD were identified. Old age (&gt;60 years), renal dysfunction, reduced ejection fraction, and presence of PAD were predictors with both MACE and major bleeding event. Among them, presence of PAD was an independent risk factor of MACE and major bleeding (MACE, HR 8.26, 95% CI 2.33- 29.41, p=0.036; major bleeding, HR 3.11, 95% CI 1.10–10.63, p=0.040, respectively). The MACE and major bleeding rate at 5-year was significantly increased in patients with PAD (MACE, 30.0% vs. 15.8%, log rank test p&lt;0.001; major bleeding, 6.7 vs. 3.6%, log rank test p=0.003, respectively) (Figure).

Conclusion

Presence of PAD was strongly associated with higher rate of long-term MACE and major bleeding. These findings could have a clinical relevance in requiring individualized pharmacologic strategies to reduce the burden of cardiovascular disease.

Funding Acknowledgement

Type of funding sources: None.

Impact of active and stable cancer on survival in patients undergoing percutaneous coronary intervention

Background

With advances in treatment of ischemic heart disease and cancer treatment, use of percutaneous coronary intervention (PCI) in cancer survivors and patients with active cancer (AC) is expanding.

Objectives

The purpose of this study was to determine the impact of cancer on survival and major cardiovascular events (MACE) in a long-term, single-center cohort of patients treated with PCI.

Methods

Patients treated with PCI between January 2010 and December 2017 were grouped as follows: controls (patients without cancer), stable cancer (SC), and AC. AC was included patients with cancer diagnosed within the past 6 months, patients who had cancer-related therapy within the past 6 months, active metastatic disease, or active recurrence of the cancer. The primary endpoints were 5-year survival and a secondary endpoint was 5-year MACE.

Results

A total of 6,743 patients (age 66±12 years, 68.4% men) treated with PCI were included: 6,404 (95.0%) controls, 245 (3.6%) SC, and 94 (1.4%) AC. Predominant malignancies were gastrointestinal (37.4%), lung (22.7%), and genitourinary cancer (14.7%). No differences were observed between patients with AC, SC and controls regarding 5-year MACE (total MACE, 33.2% vs. 28.1% vs. 17.5%, p=0.072; cardiac death, 13.6% vs. 9.1% vs. 6.7%, p=0.066; non-fatal myocardial infarction, 2.9% vs. 7.5% vs. 7.8%, p=0.820; revascularization, 17.9% vs. 17.6% vs. 11.6%, p=0.794, respectively). Patients with AC and SC had reduced 5-year survival compared with controls (62.0% vs. 81.5% vs. 89.8%, p&lt;0.001) (Figure). AC was associated with a 1.76 (95% CI 1.22 to 2.54, p=0.002) fold increased risk of all-cause 5-year mortality in multivariable adjusted models.

Conclusions

Cumulative incidence of 5-year survival was discriminated by concurrent status of cancer following PCI. Individualized decision making is needed in the routine practice of PCI regarding concurrent cancer-specific treatment and prognosis.

Funding Acknowledgement

Type of funding sources: None.

Development and Validation of a Trigger Tool for Identifying Drug-Related Emergency Department Visits

There are various trigger tools for detecting adverse drug events (ADEs), however, a drug-related emergency department (ED) visit trigger tool (DrEDTT) has not yet been developed. We aimed to develop and validate a DrEDTT with a multi-center cohort. In this cross-sectional study, we developed the DrEDTT consisting of 28 triggers through a comprehensive literature review and three phase expert group discussion. Next, we evaluated the performance of the DrEDTT by applying it to relevant medical records retrieved from four hospitals from January 2016 to June 2016. Two experts performed an in-depth chart review of a 25% of random sample of trigger flagged and unflagged ED visits and a true ADE was determined through causality assessment. Among 66,564 patients who visited the ED for reasons other than traffic accident and trauma during the study period, at least one trigger was found in 21,268 (32.0%) patients. A total of 959 true ADE cases (5.8%) were identified from a randomly selected 25% of ED visit cases. The overall positive predictive value was 14.0% (range: 8.3-66.7%). Sensitivity and specificity of DrEDTT were 77.7% and 70.4%, respectively. In conclusion, this newly developed trigger tool might be helpful to detect ADE-related ED visits.

Effects of Monotherapy with Clopidogrel vs. Aspirin on Vascular Function and Hemostatic Measurements in Patients with Coronary Artery Disease: The Prospective, Crossover I-LOVE-MONO Trial

Objectives: To evaluate the effect of clopidogrel vs. aspirin monotherapy on vascular function and hemostatic measurement. Background: Monotherapy with P2Y₁₂ receptor inhibitor vs. aspirin can be a useful alterative to optimize clinical efficacy and safety in high-risk patients with coronary artery disease (CAD). Methods: We performed a randomized, open-label, two-period crossover study in stented patients receiving at least 6-month of dual antiplatelet therapy (DAPT). Thirty CAD patients with moderate-to-high ischemic risk were randomly assigned to receive either 75 mg of clopidogrel or 100 mg of aspirin daily for 4 weeks, and were crossed over to the other strategy for 4 weeks. Vascular function was evaluated with reactive hyperemia-peripheral arterial tonometry (RH-PAT) and brachial-ankle pulse wave velocity (baPWV). Hemostatic profiles were measured with VerifyNow and thromboelastography (TEG). The primary endpoint was the reactive hyperemia index (RHI) during clopidogrel or aspirin monotherapy. Results: Clopidogrel vs. aspirin monotherapy was associated with better endothelial function (RHI: 2.11 ± 0.77% vs. 1.87 ± 0.72%, p = 0.045), lower platelet reactivity (130 ± 64 vs. 214 ± 50 P2Y12 reaction unit [PRU], p < 0.001) and prolonged reaction time (TEG R: 5.5 ± 1.2 vs. 5.1 ± 1.1 min, p = 0.037). In multivariate analysis, normal endothelial function (RHI ≥ 2.1) was significantly associated with clot kinetics (TEG angle ≤ 68 degree) and ‘PRU ≤ 132’. ‘PRU ≤ 132’ was achieved in 46.2% vs. 3.8% during clopidogrel administration vs. aspirin monotherapy (odds ratio 21.4, 95% confidence interval 2.7 to 170.1, p < 0.001). Conclusions: In CAD patients, clopidogrel vs. aspirin monotherapy was associated with better endothelial function, greater platelet inhibition and lower coagulation activity, suggesting pleiotropic effects of clopidogrel on endothelial function and hemostatic profiles.

Lung virome: New potential biomarkers for asthma severity and exacerbation

BACKGROUND

Although some respiratory virus infections are known to contribute to the development and exacerbation of asthma, commensal viromes in airway have not been extensively studied due to technical challenges.

OBJECTIVES

This study investigated the characteristics of the virome in asthmatic airways.

METHODS

Both the bacteriome and virome profiles in sputum from 12 healthy individuals, 15 patients with nonsevere asthma, and 15 patients with severe asthma were analyzed and assessed for the association with clinical characteristics such as severity, exacerbation, Asthma Control Test (ACT), and lung function.

RESULTS

While analysis of the 16S ribosomal RNA bacteriome in the airway showed no differences, clear contrasts in the diversity and composition of airway viromes were observed between healthy controls and patients with asthma. Herpesviruses were the most abundant type of virus in the asthma group (44.6 ± 4.6%), mainly with cytomegalovirus (CMV) and EBV accounting for 24.5 ± 3.3% and 16.9 ± 3.5%, respectively, in contrast to those in the healthy controls (5.4 ± 2.5% and 7.1 ± 3.0%, respectively). CMV and EBV were more abundant in patients with asthma who experienced exacerbation, and their abundance showed correlation with more severe asthma, lower ACT score, and lower lung function. On the contrary, bacteriophage that is abundant in healthy controls was severely reduced in patients with asthma in the order of nonsevere and severe asthma and presented significant positive correlation with ACT and FEV₁/forced vital capacity.

CONCLUSIONS

Lung viromes, especially, CMV, EBV, and bacteriophage may be potential biomarkers of asthma severity and exacerbation.

Universal Multienergy Harvester Architecture

The energy available in the ambient vibrations, magnetic fields, and sunlight can be simultaneously or independently harvested using universal architecture. The universal harvester design is shown to effectively convert ambient magnetic fields, vibration, and light into electricity. The architecture is composed of a perovskite solar cell integrated onto a magnetoelectric composite cantilever beam. The efficiency of the large-area perovskite solar cell is shown to reach 15.74% (cell area is >1100% larger than traditional perovskite solar cells) by selecting glass/indium tin oxide (ITO) as the cathode that reduces the charge recombination. The magnetoelectric composite beam is designed to include the effect of the mass and volume of the solar cell on power generation. Results demonstrate that universal energy harvester can simultaneously capture vibration, magnetic fields, and solar irradiation to provide an ultrahigh-power density of 18.6 mW/cm³. The total power generated by the multienergy harvester, including vibration, magnetic field, and solar stimuli, is 23.52 mW from a total surface area of 9.6 cm² and a total volume of 1.26 cm³. These results will have a tremendous impact on the design of the power sources for Internet of Things sensors and wireless devices.

Probiotic NVP-1703 Alleviates Allergic Rhinitis by Inducing IL-10 Expression: A Four-week Clinical Trial

Although several recent studies reported that probiotics might be beneficial for allergic rhinitis (AR), the effect of probiotics on AR is not consistent and have not been reproduced between studies. We aimed to determine the efficacy and safety of probiotic NVP-1703, a mixture of Bifidobacterium longum and Lactobacillus plantarum, in subjects with perennial AR. Adult subjects with perennial AR received either NVP-1703 (n = 47) or placebo (n = 48) for four weeks. Total nasal symptom scores (TNSS), rhinitis control assessment test (RCAT), blood eosinophil count, allergen-specific IgE, and immunological parameters in serum and urine were compared at baseline and after four weeks. TNSS changes from baseline at weeks 1, 3, and 4 were significant between the NVP-1703 and placebo groups (p = 0.033, 0.031, and 0.029, respectively). RCAT score showed significant differences between the NVP-1703 and placebo groups (p = 0.049) at week 4. Dermatophagoides farinae-specific IgE levels and serum IL-10 levels were significantly different between the NVP-1703 and placebo groups (p = 0.033 and p = 0.047, respectively). IL-10/IL-4 and IL-10/IL-13 ratios were different between the NVP-1703 and placebo groups at week 4 (p = 0.046 and 0.018, respectively). NVP-1703 treatment reduced urinary prostaglandin F_2α and leukotriene E₄ levels (p > 0.05). Therefore, NVP-1703 can be treatment option for perennial AR.

Fractional exhaled nitric oxide and forced expiratory volume in 1 second/forced vital capacity have predictive value of asthma exacerbation in Korean school children

Background

The incidence of asthma exacerbation (AE) and the predictive value of spirometry and fractional exhaled nitric oxide (FeNO) in school children have not been evaluated.

Objective

We sought to evaluate the efficacy of spirometry measurement and FeNO monitoring for predicting AE in school children in the Cheongju area in Korea.

Methods

With parental agreement, we studied 170 students aged 7–12 years. Children were evaluated by an asthma specialist using baseline spirometry, skin prick test, seasonal FeNO measurement, and asthma control test. The study participants underwent a physical examination and their medical history was also evaluated by the specialist. They were assessed for asthma control status during regular doctor visits for 1 year.

Results

In total, 160 children (94.1%) completed follow-up and FeNO monitoring. Of which, 26 children (16.3%) had AE. AE was associated with male children and children with allergic rhinitis (p < 0.05). While, children with AE tended to have higher FeNO than those without AE, no significant difference was found. The maximum value of FeNO ≥35 ppb was associated with AE (p < 0.05). Children with AE had a significantly decreased baseline forced expiratory volume in 1 second/forced vital capacity (FEV₁/FVC), %predicted, forced expiratory flow at 25%–75% of FVC (FEF_25%–75%). FEV₁/FVC < 80% was associated with AE in children regardless of inhalant allergen sensitization (all p < 0.05).

Conclusion

Baseline spirometry had a predictive value of AE in school children. Sensitive spirometric parameters such as FEV₁/FVC and FEF_25%–75% can be used as prognostic factors to predict future childhood AE. FeNO value ≥ 35 ppb during monitoring was associated with AE in school children.

P1416 Clinical importance of consecutive transthoracic echocardiography in the patients with hypertrophic cardiomyopathy

Funding Acknowledgements

nothing

OnBehalf

nothing

Background

prediction of outcomes Hypertrophic cardiomyopathy (HCM) have been robustly analyzed with echocardiography. However, there is limited data of serial follow-up (FU) transthoracic echocardiography (TTE) to predict outcomes in patients with HCM.

Objectives

This study aim is to discover clinical predictors associated with consecutive TTE follow-up in patients with HCM.

Methods

From 2010 to 2016, 162 patients with HCM were enrolled retrospectively. Concentric LVH and others systolic disease related to wall thickness were excluded. Index TTE (baseline) was measured when firstly admitted in our hospital. FU TTE was analyzed at the end of follow-up, defined as the last recorded value in patients who did not develop events or the last recorded value before events developed.

Results

The average of FU TTE and clinical FU period was 3.7 ± 2.0 years. Clinical outcomes were defined as stroke, syncope, heart failure, arrhythmia and death. Interestingly, only baseline TR V max was a predictor for clinical outcome whereas the others echo parameters were not associated with events (Table 1). KM curve showed the TR Vmax ≥2.5m/s was also significant (log rank = 0.008, Fig 1.)

Conclusions Our study showed short-term FU TTE did not bring clinician with clinical benefits in the aspect of prediction for events. Only baseline TR V max was good correlation with cardiovascular outcomes and even in the survival analysis.

Serial TTE and changed values Total N = 162 index TTE (baseline) FU TTE Change of FU per year event no event p-value event no event p-value event no event p-value IVDd, mm 14 ± 4 15 ± 5 0.500 15 ± 5 14 ± 5 0.758 0.23 ± 0.51 -0.07 ± 1.27 0.200 LVIDd, mm 47 ± 5 48 ± 6 0.256 47 ± 7 48 ± 6 0.560 -0.22 ± 2.79 0.10 ± 2.27 0.444 LVEF, % 62 ± 5 61 ± 7 0.379 61 ± 6 61 ± 10 0.927 -0.43 ± 3.10 -0.04 ± 4.94 0.620 LAVI 43 ± 9 43 ± 8 0.879 57 ± 27 58 ± 23 0.849 0.53 ± 14.5 3.11 ± 7.2 0.134 EA ratio 0.9 ± 0.6 0.9 ± 0.6 0.782 1.0 ± 0.8 0.9 ± 0.6 0.595 -0.02 ± 0.76 0.003 ± 0.027 0.594 DT,ms 196 ± 58 201 ± 62 0.603 203 ± 91 217 ± 89 0.370 17 ± 57 5 ± 40 0.154 septal e` 4.4 ± 2.1 4.2 ± 1.6 0.585 4.4 ± 1.6 4.6 ± 1.7 0.438 0.24 ± 0.91 0.05 ± 0.65 0.190 E of e` 17 ± 11 17 ± 23 0.993 15 ± 9 15 ± 6 0.726 -0.48 ± 4.42 -1.66 ± 22.78 0.728 TR velocity 2.6 ± 0.5 2.4 ± 0.4 0.012 2.7 ± 0.6 2.6 ± 0.4 0.604 0.05 ± 0.30 0.04 ± 0.18 0.905 Max wall thickness 17 ± 3 18 ± 3 0.137 17 ± 4 17 ± 3 0.888 -0.01 ± 2.19 -0.18 ± 1.14 0.522

Abstract P1416 Figure. TR Vmax and CV outcomes in the KM curve

P3637Relationship between serial measurements of NT-proBNP and cardiovascular events in patients with acute coronary syndrome

Background

Increased level of natriuretic peptides has been known as an important predictors of adverse cardiovascular (CV) outcomes in patients with acute coronary syndrome (ACS). We sought to evaluate clinical implication of N-terminal pro-brain natriuretic peptide (NT-proBNP) measured at initial and follow-up periods.

Methods

Serial NT-proBNP levels (on-admission and one-month post-PCI) were measured in ACS patients undergoing PCI (n=2,290). High NT-proBNP levels were determined according to the predefined age-specific criteria. Patients were stratified into 4 groups according to NT-proBNP levels (on-admission & one-month): (1) normal-normal group (n=1234, 53.9%); (2) high–normal group (n=257, 11.2%); (3) normal-high group (n=376, 16.4%); and (4) high-high group (n=423, 18.5%). Clinical events were defined as all-cause death and MACE (a composite of CV death, non-fatal MI, and ischemic stroke).

Results

With a median follow-up of 35.9 (IQR: 16.8, 54.5) months, all-cause death and MACE were occurred in 4.1% and 7.2%, respectively. NT-proBNP on-admission vs. at one-month did not differ significantly (median 391.6 [IQR: 143.9, 1402.3] vs. median 619.1 [IQR 240.1, 1616.1]; p=0.622), but the prevalence of high NT-proBNP was increased over time (25.3% to 34.9%; p<0.001). The rates of all-cause death and MACE significantly increased only in the high-high group compared with other groups (log-rank test, all p values <0.001, Figure). After adjustment, the high-high group remained significantly risky in terms with the occurrence of all-cause death (HR, 2.99; 95% CI, 1.65 to 5.41; p<0.001) and MACE (HR, 1.96; 95% CI, 1.28 to 3.01; p=0.002).

Figure 1

Conclusion

Serial measurements of NT-proBNP at on-admission and follow-up can help to stratify the risks of all-cause death and adverse CV events following PCI in ACS patients. About two-fifths of patients having high NT-proBNP level during hospitalization can be classified into the low-risk group for all-cause death and adverse CV events.

Acknowledgement/Funding

None

Cost implications of adverse drug event-related emergency department visits - a multicenter study in South Korea

Background: Adverse drug reactions (ADRs) increase health-care resource utilization, including that for emergency department (ED) visits. However, cost analyses of ADRs resulting in ED visits are scarce. Therefore, we aimed to estimate the direct medical costs before and after ADR occurrence and analyzed the cost-driving factors.Methods: The ADR cases were identified by a retrospective review of medical records of patients who visited the ED of three tertiary hospitals in South Korea from July to December 2014. The direct medical cost was estimated by the difference in costs six months before and after the ED visit. A generalized linear model was used to identify the ADR-associated cost-driving factors.Results: The mean cost per ADR increased by 26.1% (±SD = 4.3) during the six-month follow-up compared with that during the six months before the ED visit (p < 0.05). Preventable ADRs accounted for approximately 19.9% of the cost increase among all ADR cases. The regression analysis revealed that 'ADR-related hospitalization' was a significant (p < 0.05) factor leading to an increase in the direct medical costs.Conclusion: Drug-related ED visits increase the burden on health insurance systems and patients' out-of-pocket costs, mostly due to the hospitalization costs.

Direct costs of severe cutaneous adverse reactions in a tertiary hospital in Korea

BACKGROUND/AIMS

There are only a few reports on the direct costs of severe cutaneous adverse reactions (SCARs), including drug reaction with eosinophilia and systemic symptoms (DRESS), Stevens-Johnson syndrome (SJS), and toxic epidermal necrolysis (TEN), despite the tremendous negative impact these reactions can have on patients. We estimated the direct costs of treating SCARs.

METHODS

Patients admitted to a tertiary teaching hospital for the treatment of SCARs from January 1, 2005 to December 31, 2010 were included. Patients who had experienced SCARs during their admission for other medical conditions were excluded. The direct costs of hospitalization and outpatient department visits were collected. Inpatient and outpatient care costs were calculated, and factors affecting inpatient care costs were analyzed.

RESULTS

The total healthcare cost for the management of 73 SCAR patients (36 with DRESS, 21 with SJS, and 16 with TEN) was 752,067 US dollars (USD). Most of the costs were spent on inpatient care (703,832 USD). The median inpatient care cost per person was 3,720 (range, 1,133 to 107,490) USD for DRESS, 4,457 (range, 1,224 to 21,428) USD for SJS, and 8,061 (range, 1,127 to 52,220) USD for TEN. Longer hospitalization significantly increased the inpatient care costs of the patients with DRESS (by 428 USD [range, 395 to 461] per day). Longer hospitalization and death significantly increased the inpatient care costs of the patients with SJS/TEN (179 USD [range, 148 to 210] per day and an additional 14,425 USD [range, 9,513 to 19,337] for the deceased).

CONCLUSION

The management of SCARs required considerable direct medical costs. SCARs are not only a health problem but also a significant financial burden for the affected individuals.

Nanoscale Texturing and Interfaces in Compositionally Modified Ca3Co4O9 with Enhanced Thermoelectric Performance

Oxide thermoelectric materials are nontoxic, chemically and thermally stable in oxidizing environments, cost-effective, and comparatively simpler to synthesize. However, thermoelectric oxides exhibit comparatively lower figure of merit (ZT) than that of metallic alloy counterparts. In this study, nanoscale texturing and interface engineering were utilized for enhancing the thermoelectric performance of oxide polycrystalline Ca₃Co₄O₉ materials, which were synthesized using conventional sintering and spark plasma sintering (SPS) techniques. Results demonstrated that nanoscale platelets (having layered structure with nanoscale spacing) and metallic inclusions provide effective scattering of phonons, resulting in lower thermal conductivity and higher ZT. Thermoelectric measurement direction was found to have a significant effect on the magnitude of ZT because of the strong anisotropy in the transport properties induced by the layered nanostructure. The peak ZT value for the Ca_2.85Lu_0.15Co_3.95Ga_0.05O₉ specimen measured along both perpendicular and parallel directions with respect to the SPS pressure axis is found be 0.16 at 630 °C and 0.04 at 580 °C, respectively. The peak ZT of 0.25 at 670 °C was observed for the spark plasma-sintered Ca_2.95Ag_0.05Co₄O₉ sample. The estimated output power of 2.15 W was obtained for the full size model, showing high-temperature thermoelectric applicability of this nanostructured material without significant oxidation.

Self-Powered Temperature-Mapping Sensors Based on Thermo-Magneto-Electric Generator

We demonstrate a thermo-magneto-electric generator (TMEG) based on second-order phase transition of soft magnetic materials that provides a promising pathway for scavenging low-grade heat. It takes advantage of the cyclic magnetic forces of attraction and repulsion arising through ferromagnetic-to-paramagnetic phase transition to create mechanical vibrations that are converted into electricity through piezoelectric benders. To enhance the mechanical vibration frequency and thereby the output power of the TMEG, we utilize the nonlinear behavior of piezoelectric cantilevers and enhanced thermal transport through silver (Ag) nanoparticles (NPs) applied on the surface of a soft magnet. This results in large enhancement of the oscillation frequency reaching up to 9 Hz (300% higher compared with that of the prior literature). Optimization of the piezoelectric beam and Ag NP distribution resulted in the realization of nonlinear TMEGs that can generate a high output power of 80 μW across the load resistance of 0.91 MΩ, which is 2200% higher compared with that of the linear TMEG. Using a nonlinear TMEG, we fabricated and evaluated self-powered temperature-mapping sensors for monitoring the thermal variations across the surface. Combined, our results demonstrate that nonlinear TMEGs can provide additional functionality including temperature monitoring, thermal mapping, and powering sensor nodes.

Age-related prevalence of chronic rhinosinusitis and nasal polyps and their relationships with asthma onset

BACKGROUND

Chronic rhinosinusitis (CRS) is a major disease condition with high morbidity and can influence lower airway disease status in adults. However, its associations with adult asthma onset and activity have not been examined in detail in a general adult population.

OBJECTIVE

To investigate relationships between CRS with nasal polyps (CRSwNP) and asthma characteristics.

METHODS

A cross-sectional data set of 17,506 adult participants (≥18 years old) in the Korean National Health and Nutrition Examination Survey from 2010 through 2012 was analyzed. CRS was defined using structured questionnaires according to the international guideline, and presence of nasal polyps was objectively assessed using nasal endoscopy. Presence of asthma and its onset and current activity were assessed using structured questionnaires.

RESULTS

CRS was significantly related to asthma, but the relationships were distinct by CRS and asthma status. CRSwNP was significantly associated with adult-onset asthma (onset after 18 years of age) or late-onset asthma (onset after 40 years of age), whereas CRS without nasal polyps was related to childhood-onset asthma (onset before 18 years) or early-onset asthma (onset before 40 years) in adults. The 2 CRS subgroups showed significant associations with current asthma but not with past asthma. However, the comorbid asthma rate was lower than 10% among subjects with CRS.

CONCLUSION

This study found distinct age-related patterns of CRSwNP and asthma and demonstrated their significant associations in a general population. However, the low prevalence of asthma in CRSwNP is in sharp contrast to findings in Western populations, which warrants further investigation for ethnic or regional differences in relationships between CRSwNP and asthma.

Multifaceted interventions to reduce acute exacerbations in elderly asthmatics

Background

Although many risk factors are known to be associated with poor asthma outcomes in the elderly, the literature on the effect of risk factor control on asthma outcomes in the elderly is very sparse.

Objective

To evaluate the role of multifaceted interventions in reducing acute exacerbations in elderly asthmatics.

Methods

A total of 100 subjects were randomly selected from our prospective cohort of elderly asthmatics aged 65 years or older and were provided multifaceted intervention for 1 year. Our multifaceted interventions included repeated education on asthma and inhaler technique for patients and their caregivers, provision of an action plan to cope with acute exacerbations, short message service to prevent follow-up losses, and oral replacement of magnesium. The primary outcome was an acute asthma exacerbation rate compared to the previous year.

Results

Ninety-two subjects completed this study, although only 58 subjects continued to take magnesium. Compared to the previous year, the acute asthma exacerbation rate showed a significant reduction from 67% to 50% (p = 0001) and significant improvement was observed in forced expiratory volume in 1 second (FEV₁) and forced vital capacity (FVC) (p = 0.04, p = 0.036 for each). Interestingly, a subgroup analysis revealed that predicted value of FEV₁ increased significantly in subjects who continued to take magnesium from 79.6% to 87.1% (p = 0.008).

Conclusion

To reduce acute exacerbations in elderly asthmatics, a multifaceted approach in increase medical awareness, proficiency and adherence to inhaler, assistance of caregivers and correction of micronutrients deficiency is likely to be effective. In addition, a continuous oral replacement of magnesium may increase FEV₁ in elderly asthmatics.

Epidemiology of drug-induced anaphylaxis in a tertiary hospital in Korea

BACKGROUND

Epidemiology and risk factors of drug-induced anaphylaxis are difficult to estimate due to lack of confirmative diagnosis and under reporting. Here we report the current state of drug-induced anaphylaxis in Korea based on an in-hospital pharmacovigilance database in a tertiary hospital.

METHODS

This study is a retrospective analysis of drug-induced anaphylaxis, reported to an in-hospital pharmacovigilance center in Seoul National University Hospital from June 2009 to May 2013. Anaphylaxis occurred in patients under 18 years of age or developed by medications administered from outside pharmacies or hospitals were excluded. We assessed causative drug, incidence per use of each drug and risk factors of fatal anaphylactic shock.

RESULTS

A total of 152 in-hospital drug-induced anaphylaxis cases were reported during the study period. The single most frequently reported drug was platinum compound and the incidence of anaphylaxis and anaphylactic shock in platinum compounds users was 2.84 and 1.39 per 1000 patients use. Risk factors of anaphylactic shock among total anaphylaxis cases were identified as older age ≥70 years [Odd's ratio (OR), 5.86; 95% confidence interval (CI), 1.70-20.14]. The use of iodinated contrast media (OR, 6.19; 95% CI, 1.87-20.53) and aminosteroid neuromuscular blocking agent (NMBA) (OR, 12.82; 95% CI, 1.50-109.92) were also a risk factor for the development of anaphylactic shock.

CONCLUSIONS

Platinum compounds are the most commonly reported causative agents of in-hospital drug-induced anaphylaxis. Older age ≥70 years and drugs such as iodinated contrast media and aminosteroid NMBA are related with high risk of anaphylactic shock.

Korean version of the Cough Symptom Score: clinical utility and validity for chronic cough

BACKGROUND/AIMS

The Cough Symptom Score (CSS) is a simple, useful tool for measuring cough severity. However, there is no standard Korean version of the CSS. We developed a Korean version of the CSS and evaluated its clinical utility and validity for assessing chronic cough severity.

METHODS

The CSS was adapted for Korean use following a forward-backward translation procedure. Patients with chronic cough enrolled from five university hospitals were graded using the CSS and a 100-mm linear visual analog scale (VAS) of cough severity at each visit. Patients completed the Leicester Cough Questionnaire (LCQ) upon presentation and completed the LCQ and Global Rating of Change at follow-up visits after 2 to 4 weeks. The concurrent validity, repeatability, and responsiveness of the Korean version of the CSS were determined.

RESULTS

Correlation coefficients between the CSS and LCQ, and between the CSS and VAS, were -0.66 and 0.52, respectively. There was a weak correlation between the scores for night and day symptoms (r = 0.24, p = 0.0006). The repeatability of the CSS in patients with no change in cough (n = 23) was high (intra-class correlation coefficient, 0.75; 95% confidence interval [CI], 0.51 to 0.88). Patients who reported an improvement in cough (n = 30) at follow-up visits had a significant improvement in the CSS (median, -2; 95% CI, -3 to -1; p = 0.0003).

CONCLUSIONS

The Korean version of the CSS correlated well with other tools for accessing cough severity in chronic cough patients. Therefore, it could be a reliable method for measuring chronic cough severity.

Large-scale machine learning of media outlets for understanding public reactions to nation-wide viral infection outbreaks

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The emotional public responses to a nation-wide outbreak of Middle East respiratory syndrome (MERS) in Korea was analyzed.

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Massive media outlet data was collected during the outbreak.

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An intriguing loop of information transfers between the media and the public was discovered.

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This method would be helpful for alleviating the unnecessary fear and overreaction of the public regarding infectious diseases.

From May to July 2015, there was a nation-wide outbreak of Middle East respiratory syndrome (MERS) in Korea. MERS is caused by MERS-CoV, an enveloped, positive-sense, single-stranded RNA virus belonging to the family Coronaviridae. Despite expert opinions that the danger of MERS might be exaggerated, there was an overreaction by the public according to the Korean mass media, which led to a noticeable reduction in social and economic activities during the outbreak. To explain this phenomenon, we presumed that machine learning-based analysis of media outlets would be helpful and collected a number of Korean mass media articles and short-text comments produced during the 10-week outbreak. To process and analyze the collected data (over 86 million words in total) effectively, we created a methodology composed of machine-learning and information-theoretic approaches. Our proposal included techniques for extracting emotions from emoticons and Internet slang, which allowed us to significantly (approximately 73%) increase the number of emotion-bearing texts needed for robust sentiment analysis of social media. As a result, we discovered a plausible explanation for the public overreaction to MERS in terms of the interplay between the disease, mass media, and public emotions.

Point prevalence and epidemiological characteristics of chronic cough in the general adult population: The Korean National Health and Nutrition Examination Survey 2010-2012

Cough is frequently self-limiting, but may persist longer in certain individuals. Most of previous studies on the epidemiology of chronic cough have only measured period prevalence, and thus have afforded limited information on the burden and natural course. We aimed to investigate the epidemiology of chronic cough by using a point prevalence measure in a large-scale general population.We analyzed cross-sectional data collected from 18,071 adults who participated in the Korean National Health and Nutrition Examination Survey 2010-2012. Presence and duration of current cough was ascertained by structured questionnaires, and cough was classified into acute (<3 weeks), subacute (3-8 weeks), or chronic cough (≥8 weeks). Demographic and clinical parameters were examined in relation to chronic cough.The point prevalences of acute, subacute, and chronic cough were 2.5 ± 0.2%, 0.8 ± 0.1% and 2.6 ± 0.2%, respectively. The proportion of current cough showed a steep decrease after 1 week of duration. However, 2 peaks in the prevalence of current cough were revealed; cough durations of less than 1 week and longer than 1 year were most common (31.1% and 27.7% of current cough, respectively). Subacute and chronic cough were more prevalent in the elderly (≥65 years); the positive associations with older age were independent of other confounders, including current smoking and comorbidities.This is the first report on the epidemiology of cough using a point prevalence measure in a nationally representative population sample. Our findings indicate a high burden of chronic cough among adults with current cough in the community. The dual-peak of cough duration suggested that the pathophysiology of acute and chronic cough may differ. The preponderance of elderly people in the prevalence of chronic cough warrants further investigation. In addition, more sophistication and validation of tools to define chronic cough will help our understanding of the epidemiology.

Thermo-Magneto-Electric Generator Arrays for Active Heat Recovery System

Continued emphasis on development of thermal cooling systems is being placed that can cycle low grade heat. Examples include solar powered unmanned aerial vehicles (UAVs) and data storage servers. The power efficiency of solar module degrades at elevated temperature, thereby, necessitating the need for heat extraction system. Similarly, data centres in wireless computing system are facing increasing efficiency challenges due to high power consumption associated with managing the waste heat. We provide breakthrough in addressing these problems by developing thermo-magneto-electric generator (TMEG) arrays, composed of soft magnet and piezoelectric polyvinylidene difluoride (PVDF) cantilever. TMEG can serve dual role of extracting the waste heat and converting it into useable electricity. Near room temperature second-order magnetic phase transition in soft magnetic material, gadolinium, was employed to obtain mechanical vibrations on the PVDF cantilever under small thermal gradient. TMEGs were shown to achieve high vibration frequency at small temperature gradients, thereby, demonstrating effective heat transfer.

Feasibility of a smartphone application based action plan and monitoring in asthma

Background

Asthma patients may experience acute episodic exacerbation. The guidelines recommend that written action plan should be given to asthma patients. However, no one can predict when and where acute exacerbation will happen. As people carry smart phone almost anytime and anywhere, smartphone application could be a useful tool in asthma care. We evaluated the feasibility of the ubiquitous healthcare system of asthma care using a smartphone application (snuCare) based on the self-management guideline or action plan.

Methods

Forty-four patients including fragile asthmatics were enrolled from Seoul National University Bundang Hospital between December 2011 and February 2012. They were randomly assigned into application user (n = 22) or application nonuser group (n = 22). We evaluated user-satisfaction, and clinical parameters such as asthma control, Quality of Life Questionnaire for Adult Korean Asthmatics, and the adherence of patients.

Results

The characteristics were similar at baseline between the 2 groups except those who treated with short-term systemic steroid or increased dose of systemic steroid during previous 8 weeks (user vs. nonuser: 31.8% vs. 4.5%, p = 0.020). Total of 2,226 signals was generated during 8 weeks including 5 risky states. After eight weeks, the users answered that it was very easy to use the application, which was shown in highest scores in terms of satisfaction (mean ± standard deviation, 4.3 ± 0.56). Seventy-three percent of patients answered that the application was very useful for asthma care. User group showed improved the adherence scores (p = 0.017). One patient in application user group could avoid Emergency Department visit owing to the application while a patient in nonuser group visited Emergency Department.

Conclusion

The ubiquitous healthcare system using a smartphone application (snuCare) based on the self-management guideline or action plan could be helpful in the monitoring and the management of asthma.

A Study of Piezoelectric Field Related Strain Difference in GaN-Based Blue Light-Emitting Diodes Grown on Silicon(111) and Sapphire Substrates

We investigate the strain difference in InGaN/GaN multiple quantum wells of blue light-emitting diode (LED) structures grown on silicon(1 11) and c-plane sapphire substrates by comparing the strength of piezo-electric fields in MQWs. The piezo-electric fields for two LED samples grown on silicon and sapphire substrates are measured by using the reverse-bias electro-reflectance (ER) spectroscopy. The flat-band voltage is obtained by measuring the applied reverse bias voltage that induces a phase inversion in the ER spectra, which is used to calculate the strength of piezo-electric fields. The piezo-electric field is determined to be 1.36 MV/cm for the LED on silicon substrate and 1.83 MV/cm for the LED on sapphire substrate. The ER measurement results indicate that the strain-induced piezo-electric field is greatly reduced in the LED grown on silicon substrates consistent with previous strain measurement results by micro-Raman spectroscopy and high-resolution transmission electron microscopy.

Functionally Graded Interfaces: Role and Origin of Internal Electric Field and Modulated Electrical Response

We report the tunable electrical response in functionally graded interfaces in lead-free ferroelectric thin films. Multilayer thin film graded heterostructures were synthesized on platinized silicon substrate with oxide layers of varying thickness. Interestingly, the graded heterostructure thin films exhibited shift of the hysteresis loops on electric field and polarization axes depending upon the direction of an applied bias. A diode-like characteristics was observed in current-voltage behavior under forward and reverse bias. This modulated electrical behavior was attributed to the perturbed dynamics of charge carriers under internal bias (self-bias) generated due to the increased skewness of the potential wells. The cyclic sweeping of voltage further demonstrated memristor-like current-voltage behavior in functionally graded heterostructure devices. The presence of an internal bias assisted the generation of photocurrent by facilitating the separation of photogenerated charges. These novel findings provide opportunity to design new circuit components for the next generation of microelectronic device architectures.

Chlorpheniramine-induced anaphylaxis diagnosed by basophil activation test

Chlorpheniramine is a widely prescribed H1-antihistamine for relieving urticaria or histamine-mediated allergic reactions. However, although rare, it may cause immediate hypersensitivity reactions. The diagnosis is usually made by provocation test, but its application is often limited due to comorbidities or potential risk of severe reactions. In those cases, skin tests and basophil activation tests can be considered as additional diagnostic tests for the drug allergy. Here, we report a 33-year-old female with underlying chronic urticaria, who recurrently developed anaphylaxis after chlorpheniramine administration. Intradermal test showed positive responses in the patient at 0.02 mg/mL of chlorpheniramine, but not in healthy controls. Basophil activation test showed significant up-regulation of CD63 and CD203c by chlorpheniramine. The present case reminds the rare but potential allergic risk of chlorpheniramine, and also suggests the potential utility of basophil activation test in making the diagnosis.

Comparison of Strain in GaN-Based Blue Light-Emitting Diode Grown on Silicon(111) and Sapphire Substrates

We compare the strain states and device performances of GaN-based blue light-emitting diodes (LEDs) grown on Si(111) and sapphire substrates. The strain characteristics are investigated using micro-Raman spectroscopy and high-resolution transmission electron microscopy. These analyses reveal that GaN layer grown on Si has a residual tensile strain in contrast to a compressive strain for GaN on sapphire, and quantum wells (QWs) on GaN/Si experience reduced lattice mismatch than those of GaN/sapphire. When external quantum efficiencies of LED on sapphire and Si substrates are compared, the LED on Si shows better efficiency droop characteristics and this is attributed to a decrease in piezo-electric field strength in InGaN/GaN layers owing to reduced lattice mismatch.

Enhanced piezoelectric properties of vertically aligned single-crystalline NKN nano-rod arrays

Piezoelectric materials capable of converting between mechanical and electrical energy have a great range of potential applications in micro- and nano-scale smart devices; however, their performance tends to be greatly degraded when reduced to a thin film due to the large clamping force by the substrate and surrounding materials. Herein, we report an effective method for synthesizing isolated piezoelectric nano-materials as means to relax the clamping force and recover original piezoelectric properties of the materials. Using this, environmentally friendly single-crystalline Na_xK_1-xNbO₃ (NKN) piezoelectric nano-rod arrays were successfully synthesized by conventional pulsed-laser deposition and demonstrated to have a remarkably enhanced piezoelectric performance. The shape of the nano-structure was also found to be easily manipulated by varying the energy conditions of the physical vapor. We anticipate that this work will provide a way to produce piezoelectric micro- and nano-devices suitable for practical application, and in doing so, open a new path for the development of complex metal-oxide nano-structures.

Urban-rural differences in the prevalence of allergen sensitization and self-reported rhinitis in the elderly population

BACKGROUND

Urbanization is frequently associated with allergic conditions during childhood; however, the literature lacks studies on the association between allergies and degree of urbanization in the elderly population.

OBJECTIVE

To determine how the degree of urbanization affects the prevalence of allergic sensitization and self-reported rhinitis symptoms in elderly community populations.

METHODS

The study population consisted of 1,311 elderly subjects identified from 2 community population cohort datasets who were divided into 3 groups according to the degree of urbanization (urban, semirural, and rural) where they resided. Current rhinitis symptoms were assessed using a questionnaire. Sensitization to inhalant allergen was measured using skin prick tests for 9 common allergens.

RESULTS

Sensitization to inhalant allergen showed a positive correlation with degree of urbanization (urban 17.2%, semirural 9.8%, rural 6.0%; P for trend <.001), with a significant correlation observed between house dust mite allergens and degree of urbanization. Self-reported rhinitis symptoms were mostly nonallergic, but showed a positive correlation with degree of urbanization (urban 26.8%, semirural 18.2%, rural 11.5%; P for trend <.001). Self-reported rhinoconjunctivitis also correlated with urbanization. Correlations between self-reported allergic conditions and urbanization remained statistically significant in multivariate logistic regression tests.

CONCLUSION

The present analyses found significant correlations between degree of urbanization with self-reported rhinitis symptoms and sensitization to inhalant allergen in the elderly population. These findings warrant further investigation of the roles that urban factors play in the development of elderly rhinitis and allergen sensitization.

High output piezo/triboelectric hybrid generator

Recently, piezoelectric and triboelectric energy harvesting devices have been developed to convert mechanical energy into electrical energy. Especially, it is well known that triboelectric nanogenerators have a simple structure and a high output voltage. However, whereas nanostructures improve the output of triboelectric generators, its fabrication process is still complicated and unfavorable in term of the large scale and long-time durability of the device. Here, we demonstrate a hybrid generator which does not use nanostructure but generates much higher output power by a small mechanical force and integrates piezoelectric generator into triboelectric generator, derived from the simultaneous use of piezoelectric and triboelectric mechanisms in one press-and-release cycle. This hybrid generator combines high piezoelectric output current and triboelectric output voltage, which produces peak output voltage of ~370 V, current density of ~12 μA·cm⁻², and average power density of ~4.44 mW·cm⁻². The output power successfully lit up 600 LED bulbs by the application of a 0.2 N mechanical force and it charged a 10 μF capacitor to 10 V in 25 s. Beyond energy harvesting, this work will provide new opportunities for developing a small, built-in power source in self-powered electronics such as mobile electronics.

Validation of the Korean version of the European Community Respiratory Health Survey screening questionnaire for use in epidemiologic studies for adult asthma

BACKGROUND

Standardized questionnaire is one of key instruments for general population surveys.

OBJECTIVE

The present study aimed to develop and validate the Korean version of the European Community Respiratory Health Survey (ECRHS) screening questionnaire for adult asthma surveys.

METHODS

The ECRHS screening questionnaire was translated into Korean language according to the international criteria. Study participants were prospectively recruited from six referral hospitals and one health check-up center. Comprehensibility of the translation was tested in a pilot study of 10 patients. The reliability was evaluated by internal consistency and test-retest repeatability. Validity was assess with regard to physician-diagnosed asthma.

RESULTS

A total of 100 adult asthma patients and 134 volunteers were recruited. Reliability was examined for 10 items in 100 asthmatics; Cronbach α coefficients were 0.84, and test-retest repeatability was good (Cohen κ coefficient, 0.71-1.00). Validity was assessed for 8 items in 234 participants; in particular, 'recent wheeze' showed a high sensitivity (0.89) for physician-diagnosed asthma. 'Recent asthma attack' and 'current asthma medication' showed high specificity (0.96-0.98).

CONCLUSION

The present study demonstrated that the Korean version of the ECRHS screening questionnaire was comprehensible, reliable and valid. We suggest the questionnaire to be utilized in further epidemiological studies for asthma in Korean adult populations.

Lamotrigine-induced toxic epidermal necrolysis confirmed by in vitro granulysin and cytokine assays

Lamotrigine is a recent medication which is prescribed for various neuropsychiatric conditions. It is generally well-tolerated, but recent pharmacoepidemiological evidence suggests that lamotrigine is associated with risks of developing severe cutaneous drug reactions like toxic epidermal necrolysis (TEN). However, there still remains the diagnostic challenge regarding how to confirm the drug causality in suspected cases. In most cases so far, lamotrigine causality has not been objectively demonstrated, which was possibly due to high risk of oral challenge tests or the lack of useful in vitro drug assays. Here we report a case of lamotrigine-induced TEN, of which the drug causality was confirmed by in vitro granulysin and cytokine assays.

Epidemiology of adult asthma in Asia: toward a better understanding

Asia is the world's most dynamic area. Asthma is a major chronic disease in Asia, like other continents. However, unlike childhood asthma, the epidemiological burden of asthma in Asian adults has been unclear. Here we reviewed the currently available literatures on the epidemiology of adult asthma in the Asian community populations. Adult asthma prevalence was generally lower in Asian than in Europe, but the increasing trends suggested the disease burden to rise in the near future. However, for better understanding, it may be essential to prepare for the Asian multinational network for the standardization and collaboration of research.

Basophil activation test with food additives in chronic urticaria patients

The role of food additives in chronic urticaria (CU) is still under investigation. In this study, we aimed to explore the association between food additives and CU by using the basophil activation test (BAT). The BAT using 15 common food additives was performed for 15 patients with CU who had a history of recurrent urticarial aggravation following intake of various foods without a definite food-specific IgE. Of the 15 patients studied, two (13.3%) showed positive BAT results for one of the tested food additives. One patient responded to monosodium glutamate, showing 18.7% of CD203c-positive basophils. Another patient showed a positive BAT result to sodium benzoate. Both patients had clinical correlations with the agents, which were partly determined by elimination diets. The present study suggested that at least a small proportion of patients with CU had symptoms associated with food additives. The results may suggest the potential utility of the BAT to identity the role of food additives in CU.

A ferroelectric photocatalyst for enhancing hydrogen evolution: polarized particulate suspension

Improved hydrogen evolution in a particulate-suspension system is demonstrated for K_0.5Na_0.5NbO₃ powder polarized via corona poling, providing a guideline for imposing an electric field on a ferroelectric photocatalyst.

Clinical features and prognostic factors in severe cutaneous drug reactions

BACKGROUND

Severe cutaneous adverse reactions (SCARs) include Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), and drug reaction with eosinophilia and systemic symptoms (DRESS). SJS and TEN (SJS/TEN) and DRESS are thought to be different diseases; however, they share some clinical and laboratory features. Although SCORTEN serves as an excellent prognostic marker for SJS/TEN, there is still a need for development of other prognostic markers for SCARs.

METHODS

The study population consisted of 88 SCAR patients. Clinical characteristics and clinical manifestations were compared between SJS/TEN and DRESS. Risk factor analyses for prolonged hospitalization were performed.

RESULTS

Of the 88 patients, 41 were SJS/TEN and 47 were DRESS. Mortality rates of TEN and DRESS were 9.8 and 2.1%, respectively. Allopurinol and carbamazepine were the most common causes of both SJS/TEN and DRESS (34.7 and 62.9%, respectively). Some of the systemic presentations, such as fever and laboratory abnormalities were common in both phenotypes. Thrombocytopenia tended to be related to prolonged hospitalization (longer than 3 weeks) in SJS/TEN (odds ratio, OR = 5.1, 95% confidence interval, CI 0.8-31.8, p = 0.076). In DRESS patients, leukocytosis at presentation (OR 4.8, 95% CI 1.1-20.3, p = 0.03) was related to prolonged hospitalization.

CONCLUSIONS

Clinical features of SCARs in a tertiary hospital in Korea were similar to those reported previously. SJS/TEN and DRESS shared some clinical and laboratory features. Thrombocytopenia for SJS/TEN and leukocytosis at presentation for DRESS may be useful prognostic markers for prolonged hospitalization.

Lost to follow-up in asthmatics does not mean treatment failure: causes and clinical outcomes of non-adherence to outpatient treatment in adult asthma

Purpose

Long-term asthma management is recommended to asthmatics; however, many patients do not adhere to follow-up treatment. It is unclear why many asthmatics do not adhere to follow-up treatment and long-term clinical course after discontinuation of asthma management. This study investigates the factors associated with loss to follow-up and observes the clinical course in asthmatics who discontinued asthma treatment.

Methods

A retrospective investigation was conducted after reviewing medical records of adult patients who were newly diagnosed with asthma at a university hospital in Seoul, South Korea from January 2005 to March 2007. We compared baseline demographics and the clinical and laboratory profiles of patients to see if they successfully adhered to the treatment at an outpatient clinic for at least 3 years. The clinical course and asthma control status were surveyed by telephone for patients who were lost to follow-up within 3 years.

Results

A total of 351 (73.9%) out of 475 patients were lost to follow-up within 3 years of asthma diagnosis. Patients lost to follow-up were younger and had clinical features of less severe asthma at time of diagnosis (higher FEV1 and PC20, and lower grade treatments) compared to patients who adhered to the follow-up for longer than 3 years (all P<0.05). Among the 198 responders to the telephone survey, 124 responders (62.6%) answered that they eventually discontinued asthma medication. A significantly higher proportion of the 124 responders who discontinued asthma treatment maintained symptom improvement compared to the 74 responders who continued asthma medication (77.4% vs. 55.4%, P=0.003).

Conclusions

Almost three quarters of newly diagnosed asthmatics discontinued asthma medication within 3 years despite a medical recommendation. There are considerable numbers of asthmatics who can maintain long-term asthma control status without medication.

Non-volatile control of 2DEG conductivity at oxide interfaces

The functionalization of two-dimensional electron gas (2DEG) at oxide interfaces can be realized integrating 2DEG with multifunctional oxide overlayers by epitaxial growth. Using a ferroelectric Pb(Zr0.2 Ti0.8 )O3 overlayer on 2DEG (LaAlO3 /SrTiO3 ), we demonstrate a model system of the functionalized 2DEG, where electrical conductivity of 2DEG can be reversibly controlled with a large on/off ratio (>1000) in a non-volatile way by ferroelectric polarization switching.

Fabrication and radio frequency characterization of carbon nanotube field effect transistor: evidence of quantum capacitance

We fabricated an radio frequency (RF) carbon nanotube field effect transistor (CNTFET) whose electrode shapes were standard RF designed ground-signal-ground (GSG)-type pads. The S-parameters measured from our RF CNTFET in the frequency range up to 6 GHz were fitted with an RF equivalent circuit, and the extracted gate capacitance was shown to be the capacitance value of the series combination of the electrostatic capacitance and the quantum capacitance. The effect of the channel resistance and the kinetic inductance was also discussed.