• Communications for Statistical Applications and Methods
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• v.23 no.6
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• pp.555-562
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• 2016

Interval censored data often occur in an observational study where the subject is followed periodically. Instead of observing an exact failure time, two inspection times that include it are available. There are several methods to analyze interval censored failure time data (Sun, 2006). However, in the presence of competing risks, few methods have been suggested to estimate covariate effect on interval censored competing risk data. A sub-distribution hazard model is a commonly used regression model because it has one-to-one correspondence with a cumulative incidence function. Alternatively, Klein and Andersen (2005) proposed a pseudo-value approach that directly uses the cumulative incidence function. In this paper, we consider an extension of the pseudo-value approach into the interval censored data to estimate regression coefficients. The pseudo-values generated from the estimated cumulative incidence function then become response variables in a generalized estimating equation. Simulation studies show that the suggested method performs well in several situations and an HIV-AIDS cohort study is analyzed as a real data example.

• Structural Engineering and Mechanics
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• v.76 no.2
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• pp.251-267
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• 2020

Transmission tower-line systems have come to represent one of the most important infrastructures in today's society. Recent strong earthquakes revealed that transmission tower-line systems are vulnerable to earthquake excitations, and that ground motions may arrive at such structures from any direction during an earthquake event. Considering these premises, this paper presents experimental and numerical studies on the dynamic responses of a 1000 kV ultrahigh-voltage (UHV) transmission tower-line system under different seismic incidence angles. Specifically, a 1:25 reduced-scale experimental prototype model is designed and manufactured, and a series of shaking table tests are carried out. The influence of the seismic incidence angle on the dynamic structural response is discussed based on the experimental data. Additionally, the incidence angles corresponding to the maximum peak displacement of the top of the tower relative to the ground (referred to herein as the critical seismic incidence angles) are summarized. The experimental results demonstrate that seismic incidence angle has a significant influence on the dynamic responses of transmission tower-line systems. Subsequently, an approximation method is employed to orient the critical seismic incidence angle, and a corresponding finite element (FE) analysis is carried out. The angles obtained from the approximation method are compared with those acquired from the numerical simulation and shaking table tests, and good agreement is observed. The results demonstrate that the approximation method can properly predict the critical seismic incidence angles of transmission tower-line systems. This research enriches the available experimental data and provides a simple and convenient method to assess the seismic performance of UHV transmission systems.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.7
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• pp.3105-3112
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• 2014

Purpose: To examine breast cancer (BC) incidence trends in relation to mammographic screening and risk factor prevalence in South Australia (SA). Materials and Methods: Trends in annual BC incidence rates were calculated using direct standardisation and compared with projected incidence derived from Poisson regression analysis of pre-screening rates. Annual percentage change and change time points were estimated using Joinpoint software. Biennial mammography screening participation rates were calculated using data from BreastScreen SA. Trends in overweight/obesity, alcohol use and hormone replacement therapy (HRT) use were examined using 1991-2009 Health Omnibus Survey data. Trends in total fertility were examined using data from the Australian Bureau of Statistics. Results: BC incidence increased around the time BreastScreen commenced and then stabilised in the mid-1990s. However rates have remained higher than projected, even though the proportion and age distribution of first time screening attendees stabilised around 1998. A decrease in BC incidence was observed among women aged 50-59yrs from the late-1990's but not among older women. Obesity and alcohol use have increased steadily in all age groups, while HRT use declined sharply from the late-1990s. Conclusions: BC incidence has remained higher than projected since mammography screening began. The sustained elevation is likely to be due to lead time effects, though over-diagnosis cannot be excluded. Declining HRT use has also impacted incidence trends. Implications: Studies using individual level data, which can account for changes in risk factor prevalence and lead time effects, are required to evaluate 'over-diagnosis' due to screening.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.2
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• pp.623-627
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• 2014

Background: Esophagus cancer (EC) is among the five most common cancers in both sexes in Iran, with an incidence rate well above world average. Social rank (SR) of individuals and regions are well-known independent predictors of EC incidence. The aim of current study was to assess gender and social disparities in EC incidence across Iran's provinces through 2003-2009. Materials and Methods: Data on distribution of population at province level were obtained from the Statistical Centre of Iran. Age-standardized incidence rates of EC were gathered from the National Cancer Registry. The Human Development Index (HDI) was used to assess the province social rank. Rate ratios and Kunst and Mackenbach relative indices of inequality ($RII_{KM}$) were used to assess gender and social inequalities, respectively. Annual percentage change (APC) was calculated using joinpoint regression. Results: EC incidence rate increased 4.6% and 6.5% per year among females and males, respectively. There were no gender disparities in EC incidence over the study period. There were substantial social disparities in favor of better-off provinces in Iran. These social disparities were generally the same between males and females and were stable over the study period. Conclusions: The results showed an inverse association between the provinces' social rank and EC incidence rate in Iran. In addition, I found that, in contrast with international trends, women are at the same risk of EC as men in Iran. Further investigations are needed to explain these disparities in EC incidence across the provinces.

• Pediatric Infection and Vaccine
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• v.19 no.2
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• pp.43-54
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• 2012

Group B streptococcus (GBS) is the leading cause of neonatal sepsis and meningitis in developed countries. This article reviews the neonatal invasive GBS disease, maternal GBS colonization, and prevention strategies in the context of recent epidemiological changes in Korea. Although Korean neonates had been supposed to have low incidence of invasive GBS disease, GBS has been recently reported to be the most common cause of invasive neonatal infection after 1990s. Among Korean pregnant women, GBS carriage rate in the vagina and rectum has been reported to be much lower than that in Western countries. However, it has increased in recent studies. For decision making about preventive strategy for neonatal GBS disease in Korea, further studies are required in terms of the incidence of neonatal GBS infection and serotype distribution. In addition, studies about maternal carriage rate and serotype distribution have to be continued.

• Asian Journal of Innovation and Policy
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• v.7 no.3
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• pp.534-563
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• 2018

Venture Capital Firms (VCs) encounter severe information asymmetry risks at almost every stage in their investment lifecycle. This paper explores the agency risks arising from information asymmetry during the stage of exits by VCs from the funded companies in their portfolio and how that impacts the incidence of specific types of type of exits (IPOs/M&As). In this empirical study, by using the data on IPO and M&A exits from venture capital-funded companies, we show how the ability of prospective buyers to better resolve agency risks is directly correlated with the incidence of the above exit types. Using the technique of logistic regression, we demonstrate that factors such as syndication, specialization focus of the VC firm (in terms of stage and sector) and the level of its social capital (proxied by its age and experience) drive the success rate of exits. This is one of first studies in context of exits from VC funded companies in the Indian context.

• Journal of Korean Neurosurgical Society
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• v.57 no.6
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• pp.390-395
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• 2015

There have been a few studies reporting the epidemiology of moyamoya disease in Korea. Previous studies revealed relatively high prevalence and incidence of moyamoya disease in Korea and Japan. This study was designed to provide the latest epidemiologic information of moyamoya disease in Korea. We analyzed a database comprising of 50 million people covered in Korea by the National Health Insurance Service to calculate the prevalence. The incidence was estimated by eliminating the duplicated records of previous 3 years. We summarized the prevalence and incidence according to age, sex, and local distribution. In addition, the chronological changes were demonstrated with direct standardization using the 2010 population structure information. The standardized prevalence was 6.5 per 100000 persons in 2005, which was increased to 18.1 in 2013. In the same period, standardized incidence was increased from 2.7 to 4.3 per 100000 persons. The prevalence for men was 4.9 and 8.3 for women in 2005. In 2013, the prevalence had increased for men and women to 13.8 and 25.3, respectively. The incidence for men and women was 2.2 and 3.2, respectively, in 2005. It had increased to 3.5 and 5.7, respectively. The mean age of patients was 33.5 in 2005 and increased to 42.5 in 2013. The peak prevalent age group had shifted slightly to the older age groups, with chronologically consistent female predominance. The prevalence was highest in Jeollabuk province and lowest in Ulsan city.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.7
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• pp.2757-2761
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• 2015

Background: Stomach cancer is the fourth most common cancer and the second leading cause of cancer-related death through the world. It is predicted that the number of new cancer cases will be more than 15 million cases by 2020. Regarding the lack of studies on this topic in the country, we have thoroughly examined the patho-epidemiology of stomach cancer in Iran. Materials and Methods: In this cross- sectional study data were collected retrospectively reviewing all new stomach cancer patients in Cancer Registry Center report of health deputy for Iran during a 6-year period (2003-2008). The study also examined the morphology of common stomach cancers. Trends in incidence and morphology underwent joinpoint regression analysis. Results: During the six-year period, a total of 35,171 cases of stomach cancer were registered. Average age standardized rate for females and males were equal to 7.1 and 15.1 per 100,000 persons, respectively. Most common histological type was adenocarcinoma, NOS with 21,980 cases (62.50%). The annual percentage change (APC) in age-standardized incidence rate (per 100,000) was increase in both females and males at 11.1 (CI: 4.3 to 18.3) and 9.2 (CI: 5.2 to 13.4), respectively. Conclusions: According to our results, the incidence of gastric cancer is increasing in Iran, so further epidemiological studies into the etiology and early detection are essential.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.32 no.3
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• pp.268-278
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• 2022

Objectives: This study aimed to establish a control group based on the big data from National Health Insurance Service. We also presented presented the number of incidences for each cancer, and analyzed the cancer incidence rate among Korean workers. Methods: The cohort definition was separated by 'baseline cohort', 'dynamic cohort', and 'fixed- industry cohort' according to the definition. Cancer incidence was calculated based on the Korean Standard Classification of Disease code. Incidence rate was calculated among the group of all workers and public officials. Based on the study subjects and each cohort definition, the number of observations, incidences, and the incidence rate according to sex and age groups was calculated. The incidence rate was estimated based on the incidence per 100,000 person-year, and 95% confidence intervals calculated according to the Poisson distribution. Results: The result shows that the number of cancer cases in the all-worker group decreases after the age of 55, but the incidence rate tends to increase, which is attributed to the retirement of workers over 55 years old. Despite the specific characteristics of the workers, the trend and figures of cancer incidence revealed in this study are similar to those reported in previous studies of the overall South Korean population. When comparing the incidence rates of all workers and the control group of public officials, the incidence rate of public officials is generally observed to be higher in the age group under the age of 55. On the other hand, for workers aged 60 or older, the incidence rates were 1,065.4 per 100,000 person-year for all workers and 1,023.7 per 100,000 person-year for civil servants. Conclusions: This study analyzed through health insurance data including all workers in Korea, and analyzed the incidence of cancer of workers by sex and age. In addition, further in-depth researches are needed to determine the incidence of cancer by industry.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.4
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• pp.1557-1561
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• 2014

Background: Breast cancer is the most frequently diagnosed cancer in women and estimating its relative risks and trends of incidence at the area-level is helpful for health policy makers. However, traditional methods of estimation which do not take spatial heterogeneity into account suffer from drawbacks and their results may be misleading, as the estimated maps of incidence vary dramatically in neighboring areas. Spatial methods have been proposed to overcome drawbacks of traditional methods by including spatial sources of variation in the model to produce smoother maps. Materials and Methods: In this study we analyzed the breast cancer data in Iran during 2004-2008. We used a method proposed to cover spatial and temporal effects simultaneously and their interactions to study trends of breast cancer incidence in Iran. Results: The results agree with previous studies but provide new information about two main issues regarding the trend of breast cancer in provinces of Iran. First, this model discovered provinces with high relative risks of breast cancer during the 5 years of the study. Second, new information was provided with respect to overall trend trends o. East-Azerbaijan, Golestan, North-Khorasan, and Khorasan-Razavi had the highest increases in rates of breast cancer incidence whilst Tehran, Isfahan, and Yazd had the highest incidence rates during 2004-2008. Conclusions: Using spatial methods can provide more accurate and detailed information about the incidence or prevalence of a disease. These models can specify provinces with different health priorities in terms of needs for therapy and drugs or demands for efficient education, screening, and preventive policy into action.