Lee, Hun;Kang, David Sung Yong;Ha, Byoung Jin;Choi, Jin Young;Kim, Eung Kweon;Seo, Kyoung Yul;Kim, Tae-im
Yonsei Medical Journal
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v.59
no.9
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pp.1115-1122
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2018
Purpose: To investigate biomechanical properties of the cornea using a dynamic Scheimpflug analyzer according to age. Materials and Methods: In this prospective, cross-sectional, observational study, participants underwent ophthalmic investigations including corneal biomechanical properties, keratometric values, intraocular pressure (IOP), and manifest refraction spherical equivalent (MRSE). We determined the relationship of biomechanical parameters and ocular/systemic variables (participant's age, MRSE, IOP, and mean keratometric values) by piecewise regression analysis, association of biomechanical parameters with variables by Spearman's correlation and stepwise multiple regression analyses, and reference intervals (RI) by the bootstrap method. Results: This study included 217 eyes of 118 participants (20-81 years of age). Piecewise regression analysis between Corvis-central corneal thickness (CCT) and participant's age revealed that the optimal cut-off value of age was 45 years. No clear breakpoints were detected between the corneal biomechanical parameters and MRSE, IOP, and mean keratometric values. Corneal velocity, deformation amplitude, radius, maximal concave power, Corvis-CCT, and Corvis-IOP exhibited correlations with IOP, regardless of age (all ages, 20-44 years, and over 44 years). With smaller deformation amplitude and corneal velocity as well as increased CorvisIOP and Corvis-CCT, IOP became significantly increased. We provided the results of determination of confidence interval from RI data using bootstrap method in three separate age groups (all ages, 20-44 years, and over 44 years). Conclusion: We demonstrated multiple corneal biomechanical parameters according to age, and reported that the corneal biomechanical parameters are influenced by IOP.
Purpose: This study was conducted to explore the mediating effect of menopausal symptoms in the relationship between occupational stress and quality of Life in middle-aged working women Method: Data collection was conducted from May 2019 to July 2019. A sample of 130 middle-aged working women was recruited from three cities in Korea. The collected data were analyzed using descriptive statistics, t-tset, ANOVA, Scheffé test, pearson correlation, and a three step regression analysis. The mediating effect was analyzed using PROCESS macro with a 95.0% bias corrected bootstrap confidence interval (5,000 bootstraps resampling). Results: Quality of life had a negative correlation with occupational stress and menopausal symptoms, while there was a positive correlation between occupational stress and menopausal symptoms. Menopausal symptoms showed a direct effect on quality of life through occupational stress as a mediating variable. Conclusion: These results suggest that menopausal symptoms should be considered when developing interventions to improve quality of life through occupational stress control of middle-aged working women
Purpose: This study was to investigate the mediating effects of health concern and depression on the stress and fatigue of COVID-19 self-quarantine. Methods: This was a cross-sectional study. A total of 227 people with COVID-19 self-quarantine experience were recruited during May 2021. Participants were invited to complete self-reported questionnaires that measure stress, health concern, depression, fatigue and demographic information. The data obtained were analyzed using multiple regression and dual mediation model applying the PROCESS macro with 95% bias-corrected bootstrap confidence interval. Results: This study analyzed the direct effects of COVID-19 stress on the health concern, depression and fatigue. And COVID-19 stress had indirect effects on their fatigue via health concern and depression. Both health concern and depression had dual mediating effects in the influence of COVID-19 stress on fatigue. In the relationship between COVID-19 stress and fatigue, the mediating effect of depression was significant. Conclusion: Fatigue due to prolonged COVID-19 can be alleviated by managing stress and mediating health concern and depression, and so therefore active nursing intervention is required.
This study estimates the productivity change of pharmaceutical industry and decompose the change into technical efficiency change and technological change to explore ways to improve the productive efficiency. Unlike most previous studies, this study employs the non-radial and non-oriented slacks-based Malmquist productivity index which can deals directly with the input excesses and output shortfalls. In addition a smoothed bootstrap method is applied to estimate statistical confidence intervals for the Malmquist Index and its components. For the empirical analysis a balanced panel data set is constructed covering ten years over the period from 2005 to 2014. The input variables used in this study are number of workers, tangible assets and major production cost. The gross production is selected as a main output variable. The empirical results suggest that the productivity of pharmaceutical industry has decreased due mainly to decline in the technological progress rather than improvements in technical efficiency. An analysis result shows that the scale efficiency outweighs the pure efficiency in determining the technical efficiency of pharmaceutical industry. Therefore, in order to enhance the competitiveness of domestic pharmaceutical industry, it is important to continue supporting policies to promote the technology innovation capability through efficient R&D investment and industry reform strategy.
Parametric and nonparametric coupled with bootstrap simulation technique were used to reevaluate previously defined reference intervals of serum chemistry parameters. A population-based study was performed in 100 clinically healthy dogs that were retrieved from the medical records of Kangwon National University Animal Hospital during 2005-2006. Data were from 52 males and 48 females(1 to 8 years old, 2.2-5.8 kg of body weight). Chemistry parameters examined were blood urea nitrogen(BUN)(mg/dl), cholesterol(mg/dl), calcium(mg/dl), aspartate aminotransferase(AST)(U/L), alanine aminotransferase(ALT)(U/L), alkaline phosphatase(ALP)(U/L), and total protein(g/dl), and were measured by Ektachem DT 60 analyzer(Johnson & Johnson). All but calcium were highly skewed distributions. Outliers were commonly identified particularly in enzyme parameters, ranging 5-9% of the samples and the remaining were only 1-2%. Regardless of distribution type of each analyte, nonparametric methods showed better estimates for use in clinical chemistry compare to parametric methods. The mean and reference intervals estimated by nonparametric bootstrap methods of BUN, cholesterol, calcium, AST, ALT, ALP, and total protein were 14.7(7.0-24.2), 227.3(120.7-480.8), 10.9(8.1-12.5), 25.4(11.8-66.6), 25.5(11.7-68.9), 87.7(31.1-240.8), and 6.8(5.6-8.2), respectively. This study indicates that bootstrap methods could be a useful statistical method to establish population-based reference intervals of serum chemistry parameters, as it is often the case that many laboratory values do not confirm to a normal distribution. In addition, the results emphasize on the confidence intervals of the analytical parameters showing distribution-related variations.
Dong Ik Cha;Kyung Mi Jang;Seong Hyun Kim;Young Kon Kim;Honsoul Kim;Soo Hyun Ahn
Korean Journal of Radiology
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v.21
no.4
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pp.402-412
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2020
Objective: To evaluate the performance of predicting early recurrence using preoperative factors only in comparison with using both pre-/postoperative factors. Materials and Methods: We retrospectively reviewed 549 patients who had undergone curative resection for single hepatcellular carcinoma (HCC) within Milan criteria. Multivariable analysis was performed to identify pre-/postoperative high-risk factors of early recurrence after hepatic resection for HCC. Two prediction models for early HCC recurrence determined by stepwise variable selection methods based on Akaike information criterion were built, either based on preoperative factors alone or both pre-/postoperative factors. Area under the curve (AUC) for each receiver operating characteristic curve of the two models was calculated, and the two curves were compared for non-inferiority testing. The predictive models of early HCC recurrence were internally validated by bootstrap resampling method. Results: Multivariable analysis on preoperative factors alone identified aspartate aminotransferase/platelet ratio index (OR, 1.632; 95% CI, 1.056-2.522; p = 0.027), tumor size (OR, 1.025; 95% CI, 0.002-1.049; p = 0.031), arterial rim enhancement of the tumor (OR, 2.350; 95% CI, 1.297-4.260; p = 0.005), and presence of nonhypervascular hepatobiliary hypointense nodules (OR, 1.983; 95% CI, 1.049-3.750; p = 0.035) on gadoxetic acid-enhanced magnetic resonance imaging as significant factors. After adding postoperative histopathologic factors, presence of microvascular invasion (OR, 1.868; 95% CI, 1.155-3.022; p = 0.011) became an additional significant factor, while tumor size became insignificant (p = 0.119). Comparison of the AUCs of the two models showed that the prediction model built on preoperative factors alone was not inferior to that including both pre-/postoperative factors {AUC for preoperative factors only, 0.673 (95% confidence interval [CI], 0.623-0.723) vs. AUC after adding postoperative factors, 0.691 (95% CI, 0.639-0.744); p = 0.0013}. Bootstrap resampling method showed that both the models were valid. Conclusion: Risk stratification solely based on preoperative imaging and laboratory factors was not inferior to that based on postoperative histopathologic risk factors in predicting early recurrence after curative resection in within Milan criteria single HCC patients.
Objective: This study aimed to develop and validate models using radiomics features on a native T1 map from cardiac magnetic resonance (CMR) to predict left ventricular reverse remodeling (LVRR) in patients with nonischemic dilated cardiomyopathy (NIDCM). Materials and Methods: Data from 274 patients with NIDCM who underwent CMR imaging with T1 mapping at Severance Hospital between April 2012 and December 2018 were retrospectively reviewed. Radiomic features were extracted from the native T1 maps. LVRR was determined using echocardiography performed ≥ 180 days after the CMR. The radiomics score was generated using the least absolute shrinkage and selection operator logistic regression models. Clinical, clinical + late gadolinium enhancement (LGE), clinical + radiomics, and clinical + LGE + radiomics models were built using a logistic regression method to predict LVRR. For internal validation of the result, bootstrap validation with 1000 resampling iterations was performed, and the optimism-corrected area under the receiver operating characteristic curve (AUC) with 95% confidence interval (CI) was computed. Model performance was compared using AUC with the DeLong test and bootstrap. Results: Among 274 patients, 123 (44.9%) were classified as LVRR-positive and 151 (55.1%) as LVRR-negative. The optimism-corrected AUC of the radiomics model in internal validation with bootstrapping was 0.753 (95% CI, 0.698-0.813). The clinical + radiomics model revealed a higher optimism-corrected AUC than that of the clinical + LGE model (0.794 vs. 0.716; difference, 0.078 [99% CI, 0.003-0.151]). The clinical + LGE + radiomics model significantly improved the prediction of LVRR compared with the clinical + LGE model (optimism-corrected AUC of 0.811 vs. 0.716; difference, 0.095 [99% CI, 0.022-0.139]). Conclusion: The radiomic characteristics extracted from a non-enhanced T1 map may improve the prediction of LVRR and offer added value over traditional LGE in patients with NIDCM. Additional external validation research is required.
Purpose: This study was investigated the mediating effect of coping behaviors in the relationship between the second victim experiences after patient safety incidents and the nursing practice changes. Methods: A cross-sectional survey was performed using structured questionnaires. Participants were 218 clinical nurses in general tertiary hospitals in South Korea. Data were collected through an online survey and snowball sampling from August 11 to September 6 2020. Data were analyzed using SPSS 23.0 program. A mediation analysis was performed using multiple regression and a simple mediation model applying the PROCESS macro with 95% bias-corrected bootstrap confidence interval. Results: The mean scores of second victim experiences was 3.41/5. Approach coping (β = .55, p < .001) and the avoidant coping (β = - .23, p = .001) showed mediation effects in the relationship between second victim experiences and constructive change in nursing practice. Avoidant coping (β = .29, p < .001) showed a mediation effect in the relationship between second victim experiences and defensive change in nursing practice. Conclusion: Coping behaviors has a mediating effect on the relationship between second victim experiences and nursing practice changes. To ensure that nurses do not experience second victim, medical institutions should have a culture of patient safety that employs a systematic approach rather than blame individuals. They also need to develop strategies that enhance approach coping and reducing avoidant coping to induce nurses' constructive practice changes in clinical nurses in experiencing second victims due to patient safety incidents.
Purpose: This study aimed to examine the moderating effect of organizational justice on the relationship between self-efficacy and nursing performance among clinical nurses. Methods: In January 2021, a cross-sectional survey was conducted with 224 clinical nurses recruited from a university-affiliated hospital in Suwon, South Korea. Participants completed online-based, self-report structured questionnaires. Collected data were analyzed using multiple regression and a simple model of PROCESS macro with a 95% bias-corrected bootstrap confidence interval. Results: Self-efficacy and organizational justice were found to be significant predictors of nursing performance. These two predictors explained the additional 34.8% variance of nursing performance in the hierarchical regression model, after adjusting the other covariates. In addition, organizational justice moderated the relationship between self-efficacy and nursing performance among the clinical nurses. In particular, at low self-efficacy level, participants with high organizational justice had higher nursing performance compared to those with low organizational justice. Conclusion: Enhancing organizational justice can be used as an organizational strategy for improving the organizational culture in terms of distribution, procedure, and interaction. Ultimately, these efforts will contribute to the improvement of nursing performance through a synergistic effect on organizational justice beyond nurses' individual competency and self-efficacy.
Purpose: This study aimed to identify the mediating effects of depression amid the influence of fear and social distancing arising from Coronavirus disease 2019 (COVID-19) in Korean women's suicidal ideation. Methods: A descriptive correlation study was conducted. Study participants, recruited by Hankook Research from March 2 to March 5, 2021, included 300 women aged 19 to 49 living in South Korea, and 100 people were randomly allocated and enlisted for each age group out of 700,000 Hankook Research Panels recruited in advance from 17 cities and provinces nationwide. Data were collected through a self-reported questionnaire and analyzed using Pearson's correlation coefficient and Hayes' Process Macro Model 4 with 95% bias-corrected bootstrap confidence interval via SPSS statistics 27.0. Results: Suicidal ideation was significantly correlated with fear of COVID-19 (r = .16, p = .006) and depression (r = .65, p < .001). The mediation effect of depression in the relationship between the fear of COVID-19 and suicidal ideation was found to be significant (B = 0.40, boot 95% CI: 0.21~0.61). However, social distancing did not significantly affect suicidal ideation via depression (B = - 0.79, boot 95% CI: - 1.94~0.26). Conclusion: It is necessary to develop and apply interventions to prevent depression and suicidal behaviors by continuously observing and reducing the negative psychological responses caused by COVID-19.
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