• The Korean Journal of Applied Statistics
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• v.36 no.5
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• pp.415-445
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• 2023

Oftentimes, the time dependent treatment covariate and the time dependent confounders exist in observation studies. It is an important problem to correctly adjust for the time dependent confounders in the propensity score analysis. Recently, In the survival data, Hade et al. (2020) used a propensity score matching method to correctly estimate the treatment delay effect when the time dependent confounder affects time to the treatment time, where the treatment delay effects is defined to the delay in treatment reception. In this paper, we proposed the Cox model based marginal structural model (Cox-MSM) framework to estimate the treatment delay effect and conducted extensive simulation studies to compare our proposed Cox-MSM with the propensity score matching method proposed by Hade et al. (2020). Our simulation results showed that the Cox-MSM leads to more exact estimate for the treatment delay effect compared with two sequential matching schemes based on propensity scores. Example from study in treatment discontinuation in conjunction with simulated data illustrates the practical advantages of the proposed Cox-MSM.

• Journal of Korean Academy of Nursing
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• v.33 no.8
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• pp.1153-1160
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• 2003

Purpose. 1) To identify the time taken from symptom onset to the arrival at the hospital (pre-hospital delay time) and time taken from the arrival at the hospital to the initiation of the major treatment (in-hospital delay time) 2) to examine whether rapid treatment results in lower mortality. 3) to examine whether the pre- and in-hospital delay time can independently predict in-hospital mortality. Methods. A retrospective study with 586 consecutive AMI patients was conducted. Results. Pre-hospital delay time was 5.25 (SD=10.36), and in-hospital delay time was 1.10 (SD=1.00) hours for the thrombolytic therapy and 50.24 (SD=121.18) hours for the percutaneous transluminal coronary angio-plasty (PTCA). In-hospital mortality was the highest when the patients were treated between 4 to 48 hours after symptom onset using PTCA (p=.02), and when treated between 30 minutes and one hour after hospital arrival using thrombolytics (p=.01). Using a hierarchical logistic regression model, the pre- and in-hospital delay times did not predict the in-hospital mortality. Conclusion. Pre- and in-hospital delay times need to be decreased to meet the desirable therapeutic time window. Thrombolytics should be given within 30 minutes after arrival at the hospital, and PTCA should be initiated within 4 hours after symptom onset to minimize in-hospital mortality of AMI patients.

• Korean Journal of Schizophrenia Research
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• v.24 no.2
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• pp.52-59
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• 2021

Objectives: Recent studies have reported that delayed initiation of clozapine can affect clinical response in patients with treatment-resistant schizophrenia (TRS). This study aimed to explore the relationship between delayed initiation of clozapine and acute treatment response. Methods: Sixty-five inpatients with TRS who started clozapine for the first time were included through a retrospective chart review. Acute treatment response was defined as a 30% reduction in the Positive and Negative Syndrome Scale score or a Clinical Global Impression of Improvement score of 1 (very much improved) or 2 (much improved) at 4 weeks after initiating clozapine. Results: After meeting the TRS criteria, the mean delay for initiating clozapine was approximately 13.8 months. The delay was shorter in patients who showed a better response to clozapine in logistic regression analysis (p=0.037). Conclusion: Our findings suggest that reducing the delay in initiating clozapine increases the effectiveness of clozapine in patients with TRS.

• Journal of Korean Academy of Nursing
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• v.30 no.3
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• pp.659-669
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• 2000

Many patients of acute myocardial infarction showed delay time before seeking treatment although they needed immediate thrombolytic therapy once they perceived their symptoms. The objectives of this study were to identify the relationship between clinical symptoms and the delay, and to find the time spent before seeking the treatment. This study was a retrospective research. The delay time for the treatment consisted of the length of delay from symptom onset to patients' decision (T1), from patients' decision making to finding transportation (T2), and from taking transportation to the first hospital arrival(T3). The subjects were 89 patients who were admitted in the ICU and Cardiac Ward at Chonnam University Hospital with the first attack of acute myocardial infarction. Center, USA The data was collected for three months from March 1st to May 31st of 1998 through questionnaires and reviewing patients' charts: The chart information was suppled by two nurses working at the ICU and Cardiac Ward. The data was analyzed by using frequency, mean and ANOVA through the SAS program. The results of study summarized as follows: 1. Sixty two patients (69.7%) were male and twenty seven patients (30.3%) were female, the ratio of male to female was 2.3 : 1. 2. In daily life, the 70.8% of the patients felt chest pain and discomfort fatigue in 67.4%, dyspnea in 57.3%, and pain in arm, neck, and jaw in 52.8%. During the attack, 97.8% of the patients felt chest pain and discomfort dyspnea in 82.1%, pain in arm, neck, jaw in 67.4% and perspiration in 51.7%. 3. The length of time a patient spent seeking time for treatment (T1+T2+T3) was 94.6 minutes, in which the time for patients' decision making for treatment (T1) was 70.3 minutes, time for finding transportation (T2) was 8.2 minutes, and time for the transportation of the patient to the first hospital (T3) was 16.1 minutes. Time for patients' decision making to go to a hospital(T1) was 74.2% of the total time sought for treatment. 4. The differences of time sought for treatment between perceptions about the seriousness of the symptoms were significant (F= 6.5, p< .01). The more serious the heart symptoms they felt, the shorter the seeking time for treatment. 5. The differences of the time delay before treatment between the degree of the symptoms were significant (F= 2.9, p< .05). The patients with the typical chest pain and discomfort spent shorter the seeking time for treatment than those with the atypical symptoms of acute myocardial infarction. 6. The differences of transportation time to the first hospital between the types of cars that the patients used, were significant (F= 4.3, p< .01). When the patients used 119 or 129 they spent the least time (5.3 minutes) for transportation, and followed by way of an ambulance (15.6 minutes), private car (20.6 minutes), and taxi (24.8 minutes).

• Kyungpook Mathematical Journal
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• v.62 no.1
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• pp.119-132
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• 2022

Virotherapy is an effective method for the treatment of cancer. The oncolytic virus specifically infects the lyse cancer cell without harming normal cells. There is a time delay between the time of interaction of the virus with the tumor cells and the time when the tumor cells become infectious and produce new virus particles. Several types of viruses are used in virotherapy and the delay varies with the type of virus. This delay can play an important role in the success of virotherapy. Our present study is to explore the impact of this delay in cancer virotherapy through a mathematical model based on delay differential equations. The partial success of virotherapy is guarenteed when one gets a stable non-trivial equilibrium with a low level of tumor cells. There exits Hopf-bifurcation by considering the delay as bifurcation parameter. We have estimated the length of delay which preserves the stability of the non-trivial equilibrium point. So when the delay is less than a threshold value, we can predict partial success of virotherapy for suitable sets of parameters. Here numerical simulations are also performed to support the analytical findings.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.10
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• pp.4339-4347
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• 2014

Purpose: This study aimed at exploring treatment delay (TD) among cancer patients in China with an attempt to develop a practical methodology facilitating frontline Chinese clinicians in promoting earlier cancer diagnosis and treatment. Materials and Methods: The study comprised framework development, qualitative interviews and paired factor rating. Framework development utilized systematic literature review, soft systems thinking and consensus groups. Qualitative interviews employed a checklist of open questions soliciting information about all the domains included the framework from cancer patients drawn via stratified randomized sampling of inpatients at 10 hospitals in Hefei, China. Paired factor rating used a self-developed computer aid and the interviewed patients as referring cases to weigh the relative importance of the factors listed in the framework in terms of their contributions to specific components of total delay (TD). Results: a) A conceptual framework was proposed consisting of a 6-step path to TD and 36 category determinants. b) A total of 227 patients were interviewed; their TD was 267.3 mean or 108 median days ranging from 0 to 2475 days; average appraisal, illness, behavioral, preparation and treatment delay accounted for 52.1%, 9.4%, 0.30%, 8.8% and 29.4% of the TD respectively. Individual side factors were rated substantially more important than environmental side factors (60% vs. 40%); most influential TD factors included cancer symptoms, overall health, family relations and knowledge about cancer and health. Conclusions: The framework proposed together with the interviewing and rating approaches used provide a potential new methodology for understanding cancer patients' TD and promoting earlier cancer treatment.

• East Asian mathematical journal
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• v.38 no.3
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• pp.357-363
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• 2022

Immunological imbalance eventually results in the development of various diseases. A typical example is an imbalance of cytokines with immunomodulatory abilities. In this paper, we propose a two-variable delay model to anti-pro-inflammatory cytokine therapy for autoimmune diseases, which are caused by an imbalance between the pro and anti-inflammatory cytokines. The interaction between pro- and anti-inflammatory cytokines were modeled mathematically to investigate the relevance of cytokines in disease processes. The delay time was estimated to maintain the stability of a biologically important steady state. In particular, the effects of delay with anti-pro-inflammatory cytokines therapy in autoinflammatory diseases were studied.

• The Journal of Pediatrics of Korean Medicine
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• v.31 no.1
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• pp.82-91
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• 2017

These are three case reports on developmental delay that were treated with Korean medicine more than one year. A child with spastic cerebral palsy was treated only with acupuncture in one case, and in another case, two children with cerebral palsy were treated with both acupuncture and Korean herbal medication: Gami-Dossi-pyengwisan and Gami-Guibiondam-tang. After more than a year of treatment period, all three children showed improvement of general condition and motor function, measured by Gross Motor Function Measure, compare to average of children with cerebral palsy. According to this result, Korean medicine treatment can be helpful in improvement of spasticity and developmental delay due to cerebral palsy. Further studies with more cases and well-designed randomized controlled trials should be performed to establish proper guideline of Korean medicine treatment for cerebral palsy.

• Journal of Korean Academy of Dental Administration
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• v.10 no.1
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• pp.1-8
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• 2022

This study introduces research on the quality of medical services, optimization of medical services, dental medical services, implant medical services, and time schedules, as well as the effective process of dental implant medical services, which is expensive and requires a long treatment period. For improvement, it is suggested to evaluate using a time schedule. In this method, a time schedule is prepared in which each step, starting from the patients appointment until the completion of the treatment process, is allotted a certain time. This schedule was finalized in consultation with the employees. When performing all implant operations, the starting time of each item was checked to evaluate the degree of compliance and to understand any reasons for delay in each step. After identifying the causes for delay at each step, suitable steps to rectify the drawbacks were developed, and an optimal plan for patient management was determined. Changes in waiting time and human resource utilization were shown as concrete data, suggesting that such a schedule is meaningful as a decision-making support tool.

• Journal of applied mathematics & informatics
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• v.39 no.5_6
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• pp.623-641
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• 2021

In this paper, numerical treatment of singularly perturbed parabolic delay differential equations is considered. The considered problem have small delay on the spatial variable of the reaction term. To treat the delay term, Taylor series approximation is applied. The resulting singularly perturbed parabolic PDEs is solved using Crank Nicolson method in temporal direction with non-standard finite difference method in spatial direction. A detail stability and convergence analysis of the scheme is given. We proved the uniform convergence of the scheme with order of convergence O(N^-1 + (∆t)²), where N is the number of mesh points in spatial discretization and ∆t is mesh length in temporal discretization. Two test examples are used to validate the theoretical results of the scheme.