• Communications for Statistical Applications and Methods
• /
• v.8 no.3
• /
• pp.815-822
• /
• 2001

The aim of this study is to estimate the seroconversion date of the human immunodeficiency virus(HIV) infection for the HIV infected patients in Korea. Data are collected from two cohorts. The first cohort is a group of "seroprevalent" patients who were seropositive and AIDS-free at entry. The other is a group of "seroincident" patients who were initially seronegative but later converted to HIV antibody-positive. The seroconversion dates of the seroincident cohort are available while those of the seroprevalent cohort are not. Estimation of seroconversion date is important because it can be used to calculate the incubation period of AIDS which is defined as the elapsed time between the HIV infection and the development of AIDS. In this paper, a Weibull regression model Is fitted for the seroincident cohort using information about the elapsed time since seroconversion and the CD4$^{+}$ cell count.The seroconversion dates for the seroprevalent cohort are imputed on the basis of the marker of maturity of HIV infection percent of CD4$^{+}$cell count.unt.

• Proceedings of the Korean Statistical Society Conference
• /
• 2004.11a
• /
• pp.243-248
• /
• 2004

The timings of two successive events of interest may not be measurable, instead it may be right censored or interval censored; this data structure is called doubly censored data. In the study of HIV, two such events are the infection with HIV and the onset of AIDS. These data have been analyzed by authors under the assumption that infection time and induction time are independent. This paper investigates the regression problem when two events arc modeled to allow the presence of a possible relation between two events as well as a subject-specific effect. We derive the estimation procedure based on Goetghebeur and Ryan's (2000) piecewise exponential model and Gauss-Hermite integration is applied in the EM algorithm. Simulation studies are performed to investigate the small-sample properties and the method is applied to a set of doubly censored data from an AIDS cohort study.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.38 no.1
• /
• pp.33-45
• /
• 2014

This study investigates urban household consumption patterns for clothing items in different income cohorts through the analysis of an Almost Ideal Demand System (AIDS) model. Korea quarterly time-series statistics data for urban household expenditures from 1990 to 2013 analyzed household demand. The price and total consumption expenditure elasticities of 4 clothing items (outer wear, shoes, clothing related services and other miscellaneous clothing) for 7 income cohorts were estimated to investigate the clothing consumption patterns of different income cohorts. The study results show that the different household income cohorts have different consumption patterns for clothing items. The elastic demand of total consumption expenditures in the lowest household income cohort suggests that they consume clothing items as luxuries while other households mostly consume them as necessities. The price elasticity for all household income cohorts and clothing items (except the highest household income cohort and outer wear) was found to be elastic. The highest household income cohort had an inelastic price demand for all clothing items that implied a less sensitive clothing consumption change for the clothing price change than other households.

• Journal of Family Resource Management and Policy Review
• /
• v.16 no.1
• /
• pp.67-83
• /
• 2012

Baby boomers are often defined by their support of their parents and their devotion to their children's educational success by providing financial and emotional aids. Now, 7.12 million baby boomers in South Korea are retiring, or are about to retire, without any retirement plans. Similar to financial stability, health, and leisure life, social capital is another important element in the quality life after retirement. This is because social capital can function as a potential resource network. Social capital is a source that provides money, information, goods, services, emotional aids, social relational opportunities etc. In the past, family and community provided social capital for the aged. However, the baby boomer generation cannot expect the same. The baby boomers have the task of creating new social capital that can assure their quality of life. Therefore, this study examines cohort characteristics of the baby boomer generation and, based on the examination, seeks an alternative for social capital. The results are as follows: First, social capital from the local community can be an alternative source of caring for the baby boomers in old age. Second, among the social capital of the local community, elderly care supported by a family friendly community is proposed. In addition, baby boomers must become the primary social capital that contributes to a mature civil society rather than a beneficiary of welfare for the aged.

• Korean Journal of Clinical Pharmacy
• /
• v.33 no.4
• /
• pp.254-260
• /
• 2023

Background: Adherence to antiretroviral treatment (ART) is crucial for maintaining the HIV-RNA suppression in patients living with HIV/AIDS. This study aims to analyze the risk factors contributing to low medication adherence among individuals with HIV/AIDS by analyzing data from the Korean HIV/AIDS cohort study. Methods: The dependent variable is ART medication adherence. The depressive symptom and anxiety scores were collected as main independence variables. Covariates included gender, age, transmission route, alcohol and smoking information, and antiviral treatment regimen details. To predict the relationship between ordinal dependent variables and independent variables, an ordered logistic regression analysis was conducted, and odds ratios (OR) were calculated. Results: The results of the ordered logistic regression analysis showed that female was associated with a higher risk of low medication adherence (OR=2.91, 95% CI=1.08, 7.83). Among the subjects who were non-smokers and non-drinkers, the risk of low medication adherence was lower (OR=0.36, 95% CI=0.18, 0.70). Depending on the ART treatment group, individuals taking integrase inhibitor had a lower risk of medication adherence (OR=0.31, 95% CI=0.13, 0.76), and those experiencing depressive symptoms were related with a higher risk of low medication adherence (OR=1.97, 95% CI=1.12, 3.46). Conclusions: The encouragement and emotional support of healthcare professionals are essential for patients living with HIV/AIDS who experience depressive symptoms to maintain ART adherence. Additionally, further research is needed to ensure that HIV/AIDS infected female with concurrent depressive symptoms can achieve appropriate ART therapeutic effect.

• Communications for Statistical Applications and Methods
• /
• v.22 no.6
• /
• pp.599-604
• /
• 2015

Kendall's tau statistic has been applied to test an association of bivariate random variables. However, incomplete bivariate data with a truncation and a censoring results in incomparable or unorderable pairs. With such a partial information, Tsai (1990) suggested a conditional tau statistic and a test procedure for a quasi independence that was extended to more diverse cases such as double truncation and a semi-competing risk data. In this paper, we also employed a conditional tau statistic to estimate an association of bivariate interval censored data. The suggested method shows a better result in simulation studies than Betensky and Finkelstein's multiple imputation method except a case in cases with strong associations. The association of incubation time and infection time from an AIDS cohort study is estimated as a real data example.

• Archives of Plastic Surgery
• /
• v.46 no.6
• /
• pp.525-534
• /
• 2019

Background In microtia patients with bilateral hearing impairment, hearing improvement is crucial for language development and performance. External auditory canal reconstruction (EACR) has been performed to improve hearing, but often results in complications. We performed transcutaneous bone conduction implant (TBCI) surgery in these patients. This study aimed to evaluate the safety and efficacy of TBCI surgery. Methods A retrospective review was performed of five patients who underwent auricular reconstruction and TBCI surgery and 12 patients who underwent EACR between March 2007 and August 2018. Hearing improvement was measured based on the air-bone gap values using pure-tone audiometry over a 6-week postoperative period. We reviewed other studies on hearing improvement using EACR and compared the findings with our results. The surgical techniques for TBCI were reviewed through case analyses. Results Postoperative hearing outcomes showed a significant improvement, with a mean gain of 34.1 dB in the TBCI cohort and 14.1 dB in the EACR cohort. Both gains were statistically significant; however, the TBCI cohort showed much larger gains. Only three of the 12 patients who underwent EACR achieved hearing gains of more than 20 dB, which is consistent with previous studies. All patients who underwent TBCI surgery demonstrated hearing gains of more than 20 dB and experienced no device-related complications. Conclusions TBCI is a safe and effective method of promoting hearing gains in microtia patients with bilateral hearing impairment. TBCI surgery provided better hearing outcomes than EACR and could be performed along with various auricular reconstruction techniques using virgin mastoid skin.

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

• Journal of Preventive Medicine and Public Health
• /
• v.49 no.6
• /
• pp.394-405
• /
• 2016

Objectives: The survival outcomes of antiretroviral treatment (ART) programs have not been systematically evaluated at the state level in India. This retrospective study assessed the survival rates and factors associated with survival among adult human immunodeficiency virus (HIV)-infected patients in Andhra Pradesh, India. Methods: The present study used data from 139 679 HIV patients aged ${\geq}15$ years on ART who were registered from 2007 to 2011 and were followed up through December 2013. The primary end point was death of the patient. Mortality densities (per 1000 person-years) were calculated. Kaplan-Meier and Cox-regression models were used to estimate survival and explore the factors associated with survival. Results: The overall median follow-up time was 16.0 months (2.0 months for the deceased and 14.0 months for those lost to follow-up). Approximately 13.2% of those newly initiated on ART died during follow-up. Of those deaths, 56% occurred in the first three months. The crude mortality rate was 80.9 per 1000 person-years at risk. The CD4 count (adjusted hazard ratio [aHR],4.88; 95% confidence interval [CI], 4.36 to 5.46 for < $100cells/mm^3$ vs. > $350cells/mm^3$), functional status (aHR, 3.05; 95% CI, 2.82 to 3.30 for bedridden vs. normal), and body weight (aHR, 3.69; 95% CI, 3.42 to 3.97 for <45 kg vs. >60 kg) were strongly associated with the survival of HIV patients. Conclusions: The study findings revealed that high mortality was observed within the first three months of ART initiation. Patients with poor baseline clinical characteristics had a higher risk of mortality. Expanded testing and counseling should be encouraged, with the goal of ensuring early enrollment into the program followed by the initiation of ART in HIV-infected patients.

• PNF and Movement
• /
• v.22 no.2
• /
• pp.257-266
• /
• 2024

Purpose: The aim of this study was to determine the influence of psychological and other risk factors on the recurrence of nonspecific neck pain. To achieve this, a nationwide cohort provided by the National Health Insurance Service in South Korea, with a three-year follow-up, was used. Methods: The study included patients who did not experience neck pain for the first year but were diagnosed with nonspecific neck pain (ICD-10 code: M54.2) in the second year. The progress of their neck pain recurrence was followed up for the next two years. Medical records, including age, gender, health insurance premium quintile, regional health vulnerability index score, initial onset duration, total hospitalization duration, and secondary diagnosis at onset, were extracted for analysis. Multivariate logistic regression analysis was performed to analyze the recurrence rate and risk factors for nonspecific neck pain recurrence. Results: Among a total of 591,215 patients, 29.2% experienced recurrence within two years. Patients with psychological disorders had a higher recurrence rate (30.6-33.8%) than those without psychological disorders (29.2%). Specifically, mood disorders (OR = 1.16) and stress-related disorders (OR = 1.06) were identified as risk factors for the recurrence of nonspecific neck pain. Older age (OR = 1.16-1.43), being female (OR = 1.17), being employed (OR = 1.23), and using medial aids (OR = 1.41) were also identified as risk factors. Conclusion: This study provides evidence for a high recurrence rate of nonspecific neck pain and highlights the need to consider psychological factors as well as personal factors in comprehensive interventions to prevent recurrent nonspecific neck pain.