Objectives: This study investigated the effects of socio-demographic factors on the decreasing trend in the sex ratio at birth from 1997 to 2017 in Korea. Methods: Data from 10 349 602 live births registered with Statistics Korea from 1997 to 2017 were analyzed. The secondary sex ratio (SSR), defined as the ratio of male to female live births, during the study period (1997-1999 [phase I], 2000-2002 [phase II], 2003-2005 [phase III], 2006-2008 [phase IV], 2009-2011 [phase V], 2012-2014 [phase VI], and 2015-2017 [phase VII]) was calculated according to selected socio-demographic factors, such as parental age, education, occupation, and birth order. Logistic regression models were used to estimate odds ratios (ORs) and 95% confidence intervals for a male birth after adjusting for potential confounders. Results: The SSR gradually decreased from 1.10 (in 1998-2000 and 2002) to 1.05 (in 2013-2016). While a decreasing trend in the SSR was not noted among first births, male-biased sex ratios were prominent among third and higher-order births, for which the highest SSR was 1.46 in 1998. Higher birth order was significantly associated with an excess of male births in phases I-VI (≥third vs. first, OR range, 1.03 to 1.35). Advanced maternal age was significantly associated with an excess of female births in phases II, III, and V (≥40 vs. 20-24 years, OR range, 0.92 to 0.95). Conclusions This study demonstrated that advanced maternal age and reduction of the artificially-biased SSR among third and higher-order births may partially explain the decreasing trend in the SSR from 1997 to 2017 in Korea.

OBJECTIVES: The aim of this study was to evaluate the impact of shifts in maternal age and parity on the increasing trends in the low birth weight (LBW) and very low birth weight (VLBW) rates from 2005 to 2015 in South Korea. METHODS: Data from 4 993 041 live births registered with Statistics Korea during the period between 2005 and 2015 were analyzed. Applying a modified standardization method, we partitioned the total increment in the LBW and VLBW rates into (1) the increase in the LBW and VLBW rates due to changes in the maternal age and parity distribution (AP-dis) and (2) the increase due to changes in the age-specific and parity-specific rates (AP-spe) of LBW and VLBW for singleton and multiple births, respectively. RESULTS: During the study period, the total increment in the LBW and VLBW rates was 1.43%p and 0.25%p, respectively. Among singleton births, changes in the AP-dis accounted for 79% (0.34%p) and 50% (0.06%p) of the total increment in the LBW and VLBW rates, respectively. Meanwhile, among multiple births, changes in the AP-dis did not contribute to the increase in the LBW and VLBW rates, with 100% of the increase in the LBW (1.00%p) and VLBW (0.13%p) rates being attributed to changes in the AP-spe. CONCLUSIONS: This study demonstrated that shifts in maternal age and parity were prominent contributors to the increase in the LBW and VLBW rates among singleton births between 2005 and 2015 in South Korea.
Female ; Humans ; Infant ; Infant, Low Birth Weight ; Infant, Newborn ; Infant, Very Low Birth Weight ; Korea ; Live Birth ; Maternal Age ; Methods ; Multiple Birth Offspring ; Parity ; Parturition

OBJECTIVES: The aim of this study was to evaluate the impact of shifts in maternal age and parity on the increasing trends in the low birth weight (LBW) and very low birth weight (VLBW) rates from 2005 to 2015 in South Korea. METHODS: Data from 4 993 041 live births registered with Statistics Korea during the period between 2005 and 2015 were analyzed. Applying a modified standardization method, we partitioned the total increment in the LBW and VLBW rates into (1) the increase in the LBW and VLBW rates due to changes in the maternal age and parity distribution (AP-dis) and (2) the increase due to changes in the age-specific and parity-specific rates (AP-spe) of LBW and VLBW for singleton and multiple births, respectively. RESULTS: During the study period, the total increment in the LBW and VLBW rates was 1.43%p and 0.25%p, respectively. Among singleton births, changes in the AP-dis accounted for 79% (0.34%p) and 50% (0.06%p) of the total increment in the LBW and VLBW rates, respectively. Meanwhile, among multiple births, changes in the AP-dis did not contribute to the increase in the LBW and VLBW rates, with 100% of the increase in the LBW (1.00%p) and VLBW (0.13%p) rates being attributed to changes in the AP-spe. CONCLUSIONS This study demonstrated that shifts in maternal age and parity were prominent contributors to the increase in the LBW and VLBW rates among singleton births between 2005 and 2015 in South Korea.

BACKGROUND: Brain volume is associated with dementia and depression in the elderly. An easy way to predict relative brain volume is to measure head circumference. In this study, we investigated the relationship between head circumference and cognition as well as depression in a non-demented elderly community.METHODS: Baseline and follow-up surveys were conducted in 2007 and 2010. At baseline, community residents aged 65 years or over (n=382) within a rural area of South Korea were screened for dementia and symptoms of depression and were followed using the same screening battery after 3 years (n=279). Data from anthropometric measurements (head circumference, height, and body weight), demographics, and blood tests were gathered. Neuropsychological tests, including the Korean version of mini-mental state examination (K-MMSE), clinical dementia rating (CDR) including the CDR-sum of boxes, the Korean version of instrumental activities of daily living, and geriatric depression scale (GDS), were performed. None of the 279 subjects followed were demented.RESULTS: Baseline performance on the K-MMSE and GDS was poorer for participants with smaller head circumferences. Follow-up performance on the MMSE was also poorer for participants with smaller head circumferences. Interestingly, participants with smaller head circumference showed worse GDS scores at baseline but on follow-up examination, participants with larger head circumference showed rapid worsening than those with smaller head circumference with marginal significance by ANOVA test. In regression coefficient analysis, GDS decline showed significant difference.CONCLUSION: Head circumference was not associated with cognitive change but was associated with symptoms of depression in non-demented community residents.
Activities of Daily Living ; Aged ; Brain ; Cognition ; Dementia ; Demography ; Depression ; Follow-Up Studies ; Head ; Hematologic Tests ; Humans ; Korea ; Mass Screening ; Neuropsychological Tests ; Prospective Studies

BACKGROUND: Brain volume is associated with dementia and depression in the elderly. An easy way to predict relative brain volume is to measure head circumference. In this study, we investigated the relationship between head circumference and cognition as well as depression in a non-demented elderly community. METHODS: Baseline and follow-up surveys were conducted in 2007 and 2010. At baseline, community residents aged 65 years or over (n=382) within a rural area of South Korea were screened for dementia and symptoms of depression and were followed using the same screening battery after 3 years (n=279). Data from anthropometric measurements (head circumference, height, and body weight), demographics, and blood tests were gathered. Neuropsychological tests, including the Korean version of mini-mental state examination (K-MMSE), clinical dementia rating (CDR) including the CDR-sum of boxes, the Korean version of instrumental activities of daily living, and geriatric depression scale (GDS), were performed. None of the 279 subjects followed were demented. RESULTS: Baseline performance on the K-MMSE and GDS was poorer for participants with smaller head circumferences. Follow-up performance on the MMSE was also poorer for participants with smaller head circumferences. Interestingly, participants with smaller head circumference showed worse GDS scores at baseline but on follow-up examination, participants with larger head circumference showed rapid worsening than those with smaller head circumference with marginal significance by ANOVA test. In regression coefficient analysis, GDS decline showed significant difference. CONCLUSION Head circumference was not associated with cognitive change but was associated with symptoms of depression in non-demented community residents.

The aim of this study was to evaluate the association between semen quality and the secondary sex ratio (SSR), defined as the ratio of male to female live births. Our study cohort comprised 227 male partners who were enrolled prior to conception in Michigan and Texas between 2005 and 2009, and prospectively followed through delivery of a singleton birth. The male partners provided a baseline and a follow-up semen sample a month apart. Semen analysis was conducted to assess 27 parameters including five general characteristics, six sperm head measures, 14 morphology measures, and two sperm chromatin stability assay measures. Modified Poisson regression models with a robust error variance were used to estimate the relative risk (RR) and 95% confidence interval (95% CI) of a male birth for each semen parameter, after adjusting for potential confounders. Of the 27 semen parameters, only the percentage of bicephalic sperm was significantly associated with the SSR (2 nd vs 1 st quartile, RR, 0.65, 95% CI, 0.45-0.95, P = 0.03; 4 th vs 1 st quartile, RR, 0.61, 95% CI, 0.38-1.00, P < 0.05 before rounding to two decimal places), suggestive of a higher percentage of bicephalic sperm being associated with an excess of female births. Given the exploratory design of the present study, this preconception cohort study suggests no clear signal that human semen quality is associated with offspring sex determination.

OBJECTIVES: While epidemiologic research indicates that the prevalence of risk-taking behaviors including cigarette smoking among young people with asthma is substantial, the longitudinal patterns of cigarette smoking in this vulnerable population have received little attention. The aim of this study was to evaluate differences in the longitudinal trajectories of cigarette use behaviors from adolescence to adulthood between young people with and without asthma. METHODS: Data from the National Longitudinal Study of Adolescent to Adult Health (Add Health) during the years 1994 to 1995 (Wave I, adolescence), 2001 to 2002 (Wave III, young adulthood), and 2007 to 2008 (Wave IV, adulthood) were analyzed (n=12 244). Latent growth curve models were used to examine the longitudinal trajectories of cigarette use behaviors during the transition to adulthood according to asthma status. RESULTS: Regardless of asthma status, the trajectory means of cigarette use behaviors were found to increase, and then slightly decrease from adolescence to adulthood. In total participants, there were no statistically significant differences in initial levels and changes in cigarette use behaviors according to asthma status. However, in select sex and race subgroups (i.e., females and non-whites), former asthmatics showed greater escalation in cigarette use behaviors than did non-asthmatics or current asthmatics. CONCLUSIONS: This study indicated that the changing patterns of cigarette use behaviors during the transition to adulthood among young people with asthma are comparable to or even more drastic than those among young people without asthma.
Adolescent ; Adolescent Behavior ; Adult ; Asthma/*pathology ; Female ; Health Status ; Humans ; Interviews as Topic ; Longitudinal Studies ; Male ; Prevalence ; Risk Factors ; *Smoking/epidemiology ; Surveys and Questionnaires ; Young Adult

BACKGROUND/AIMS: This study determined the prevalence and determinants of seropositivity for rheumatoid factor (RF), anti-cyclic citrullinated peptide (anti-CCP) antibody, and anti-mutated citrullinated vimentin (anti-MCV) antibody in unaffected first-degree relatives (FDRs) of rheumatoid arthritis (RA) patients. METHODS: A total of 337 subjects (135 with RA and 202 FDRs) were enrolled in this case-control study. Serum RF, anti-CCP antibody, and anti-MCV antibody were assayed. Subjects in multicase families (> or = 2 affected FDRs within the same family) were identified. Multivariate logistic regression analysis was used to identify risk factors associated with RA-related autoantibodies. RESULTS: Seropositivity for RF, anti-CCP antibody, or anti-MCV antibody was detected in 14.4%, 5.0%, or 13.4% of unaffected FDRs, respectively. Anti-CCP antibody seropositivity was more prevalent in FDRs in multicase families (17.8%) than in those not in multicase families (1.3%, p < 0.0001). Significant correlations between RA-associated autoantibodies were detected in the FDR group (between RF and anti-CCP antibody: r = 0.366, p < 0.0001; between RF and anti-MCV antibody: r = 0.343, p < 0.0001; and between anti-CCP antibody and anti-MCV antibody: r = 0.849, p < 0.0001). After adjustment for age and sex, anti-CCP antibody seropositivity in FDRs was significantly associated with being in a multicase family (odds ratio, 49.8; 95% confidence interval, 5.6 to 441.6). CONCLUSIONS: The association between anti-CCP antibody seropositivity in unaffected FDRs and being in a multicase family suggests that genetic and/or environmental factors may increase the risk for RA development in unaffected FDRs.
Adolescent ; Adult ; Arthritis, Rheumatoid/blood/*epidemiology/genetics/*immunology ; Autoantibodies/*blood ; Biological Markers/blood ; Case-Control Studies ; Chi-Square Distribution ; Cross-Sectional Studies ; Female ; Gene-Environment Interaction ; Genetic Predisposition to Disease ; Humans ; Logistic Models ; Male ; Middle Aged ; Multivariate Analysis ; Odds Ratio ; Pedigree ; Peptides, Cyclic/*immunology ; Republic of Korea/epidemiology ; Risk Factors ; Seroepidemiologic Studies ; Vimentin/immunology ; Young Adult

OBJECTIVE: Interstitial lung disease (ILD) is a common pulmonary manifestation of rheumatoid arthritis (RA), and an important cause of morbidity and mortality in RA. We compared demographic and clinical characteristics of usual interstitial pneumonia (UIP) and nonspecific interstitial pneumonia (NSIP) patterns in RA patients and determined the prognostic factors that influence the survival of RA-ILD patients. METHODS: 51 enrolled RA patients (male n=21, female n=30) with ILD underwent HRCT. We categorized ILD into two groups, as the UIP pattern and the NSIP pattern, using HRCT. HRCT scans were scored to investigate the extent of the ILD. We divided the extent of the interstitial lung disease into 4 groups 1~14%, 15~19%, 20~24%, >25%. RESULTS: There were no significant differences between the UIP and NSIP pattern in the clinical characteristics, except for age at the time of the study (RA-NSIP pattern vs RA-UIP pattern 62.3+/-11.7 vs 68.2+/-8.4, p=0.042). There were no significant differences in survival time between the RA-UIP and RA-NSIP pattern (Log rank p=0.985). The extent of ILD on chest HRCT was significantly associated with mortality (HR=1.044, 95% CI 1.019~1.069) and patients that were diagnosed with ILD at an older age (HR=1.109, 95% CI 1.024~1.200) were associated with a worse prognosis. Comparing four groups divided by the extent of the lung disease, there were significant differences in survival estimates (Log-rank p-value<0.001) based on an ILD extent of 15%. CONCLUSION: Our study reveals that the extent of ILD on chest HRCT was found to be significantly associated with poor prognosis of RA-ILD patients.
Arthritis, Rheumatoid ; Female ; Humans ; Idiopathic Pulmonary Fibrosis ; Lung Diseases ; Lung Diseases, Interstitial ; Prognosis ; Thorax

OBJECTIVE: Interstitial lung disease (ILD) is a common pulmonary manifestation of rheumatoid arthritis (RA), and an important cause of morbidity and mortality in RA. We compared demographic and clinical characteristics of usual interstitial pneumonia (UIP) and nonspecific interstitial pneumonia (NSIP) patterns in RA patients and determined the prognostic factors that influence the survival of RA-ILD patients. METHODS: 51 enrolled RA patients (male n=21, female n=30) with ILD underwent HRCT. We categorized ILD into two groups, as the UIP pattern and the NSIP pattern, using HRCT. HRCT scans were scored to investigate the extent of the ILD. We divided the extent of the interstitial lung disease into 4 groups 1~14%, 15~19%, 20~24%, >25%. RESULTS: There were no significant differences between the UIP and NSIP pattern in the clinical characteristics, except for age at the time of the study (RA-NSIP pattern vs RA-UIP pattern 62.3+/-11.7 vs 68.2+/-8.4, p=0.042). There were no significant differences in survival time between the RA-UIP and RA-NSIP pattern (Log rank p=0.985). The extent of ILD on chest HRCT was significantly associated with mortality (HR=1.044, 95% CI 1.019~1.069) and patients that were diagnosed with ILD at an older age (HR=1.109, 95% CI 1.024~1.200) were associated with a worse prognosis. Comparing four groups divided by the extent of the lung disease, there were significant differences in survival estimates (Log-rank p-value<0.001) based on an ILD extent of 15%. CONCLUSION: Our study reveals that the extent of ILD on chest HRCT was found to be significantly associated with poor prognosis of RA-ILD patients.
Arthritis, Rheumatoid ; Female ; Humans ; Idiopathic Pulmonary Fibrosis ; Lung Diseases ; Lung Diseases, Interstitial ; Prognosis ; Thorax