Conducting the non-inferiority test for the means with unknown coefficient of variation in a three-arm trial.

BACKGROUND: The non-inferiority test is a reasonable approach to assessing a new treatment in a three-arm trial. The three-arm trial consists of a placebo, reference, and an experimental treatment. The non-inferiority is often measured by the mean differences between the experimental and the placebo groups relative to the mean differences between the reference and the placebo groups. METHODS: To cope with possible estimation distortion due to the allowance of heteroskedasticity, we adjust the measurement of non-inferiority by the incorporation of coefficient of variation (CV) of the experimental, the reference and the placebo groups. In this research, we propose a generalized [Formula: see text]-value based method (GPV-based method) to facilitate non-inferiority tests for the means with unknown coefficient of variation in a three-arm trial. RESULTS: The simulation results show that the GPV-based method can not only adequately control type I error rate at nominal level better but also provide power higher than those from Delta method and the empirical bootstrap method, which verifies the feasibility of our adjustment. CONCLUSIONS: We revise the measurement of non-inferiority by deducting the CV of each kind of treatment from the average effect of trials. CVs are included in the non-inferiority explicitly to help prevent possible estimating distortion if heteroskedasticity is allowed. Through the simulation study, the performance of GPV-based method for facilitating non-inferiority tests for the means with unknown CV in a three-arm trial is better than those from empirical bootstrap method and Delta method for small, medium and large sample sizes. Hence, the GPV-based method is recommended to be used to conduct the non-inferiority test for the means with unknown CV in a three-arm trial. The GPV-based method still performs well in non-normality cases.

Birth outcomes and risk factors in adolescent pregnancies: results of a Taiwanese national survey.

BACKGROUND: This study explores birth outcomes and determinants in adolescent pregnancies, using subjects drawn from the Taiwan Birth Cohort Study (TBCS) from 2005. METHODS: Through completed interviews and surveys with mothers or other family members, differences in birth outcomes and personal, pregnancy and social profiles of mothers were analyzed. RESULTS: A total of 533 adolescent mothers (<20 years old) and 9347 adult mothers (20-34 years old) were included in our study. There was a significantly higher incidence of low birthweight (LBW) (<2500 g, 10.2% vs 5.6%) and premature birth (<37 weeks, 14.8% vs 8.6%) in the adolescent group. When adjusted for covariates in the multiple-variable model, youth remained a risk factor for LBW (OR = 1.50, 95%CI 1.09, 2.07) and premature delivery (OR = 1.42, 95%CI 1.07, 1.89). Age, prenatal care and weight gain during pregnancy are important predictors of LBW and premature birth. CONCLUSION: Adolescent pregnancy carries a high-risk of LBW and premature birth. Inadequate prenatal care and weight gain during pregnancy are contributing factors that could be improved through strategies of health education, family support and case management.

Comparison of Escherichia coli and Klebsiella pneumoniae liver abscesses.

BACKGROUND: Escherichia coli and Klebsiella pneumoniae are the most common causative pathogens of pyogenic liver abscesses. The objective of this study was to compare outcome between patients with liver abscesses due to E coli and those with liver abscesses caused by K pneumoniae; we also aimed to identify separately the predictors of mortality in the 2 groups. METHODS: We conducted a retrospective study of 202 patients who presented with pyogenic liver abscesses caused by either E coli or K pneumoniae from July 2000 to June 2005. Outcome of the patients was analyzed by exact logistic regression with adjustment for baseline and clinical covariates. Significant predictors of mortality in the E coli and the K pneumoniae groups were investigated by multivariate analysis of demographic and clinical variables in each group. RESULTS: Of the 202 patients (128 men and 74 women; age range, 19 to 89 years), pyogenic liver abscess was due to E coli infection in 55 patients and K pneumoniae in 147 patients. In contrast to patients with K pneumoniae, patients with E coli liver abscess were more likely to be older and female, have a biliary abnormality or malignancy, pleural effusion, polymicrobial infection with anaerobic or multi-drug-resistant organisms, a higher APACHE II score, and to have been treated initially with ineffective antibiotics; they were also less likely to have diabetes mellitus. The cause of K pneumoniae liver abscess was often cryptogenic. The sensitivity, specificity, positive predictive value, and likelihood ratio of the presence of biliary disorders and coexisting malignancy as a predictive parameter of E coli liver abscess were 25%, 96%, 67%, and 5.45/1, respectively. The sensitivity, specificity, positive predictive value, and likelihood ratio of the presence of diabetes mellitus with an abscess of cryptogenic origin as a predictive parameter of K pneumoniae liver abscess were 39%, 84%, 81%, and 2.36/1, respectively. There was no significant difference in mortality between patients with E coli and those with K pneumoniae infections (26% vs 4%; adjusted OR, 4.2; 95% CI, 0.63 to 27; P = 0.105). However, for patients with liver abscess caused by E coli, the APACHE II score at admission (OR, 1.7; 95% CI, 1.1 to 2.6; P = 0.021), malignancy (OR, 26; 95% CI, 1.8 to 370; P = 0.016), and right-lobe abscess (OR, 0.0029; 95% CI, 0.00010 to 0.15; P = 0.004) were significant predictors of death, whereas uremia (OR, 52; 95% CI, 3.5 to 750; P = 0.004) and multi-drug-resistant isolates (OR, 26; 95% CI, 2.3 to 290; P = 0.009) were significant predictors of death in the K pneumoniae group. CONCLUSIONS: A higher APACHE II score at admission and a higher frequency of coexisting malignancy may have contributed to the higher, although not significant, mortality rate in patients with liver abscess caused by E coli infection. Clinicians should begin with broad antibiotic coverage such as a second-generation cephalosporin and an aminoglycoside with metronidazole when treating liver abscesses with E coli as the likely pathogen due to the high frequency of multi-drug-resistant isolates among E coli isolates.

Epidemiology of hepatitis B virus infection among young adults in Taiwan, China after public vaccination program.

BACKGROUND: The public vaccination program of hepatitis B virus (HBV) was launched during 1984 in Taiwan, China. However, the long-lasting protective efficacy of HBV vaccination among adolescents older than 15 years of age was seldom recorded. METHODS: A seroepidemiological survey was conducted among 4575 first-year university students in Taiwan, China during 2000 to 2003, including the serological data of HBV by testing HBV surface antigen (HBsAg), surface antibody (anti-HBs), HBV core antibody (anti-HBc) and demographic information. RESULTS: HBsAg carrier rate among male university students born before the initiation of the HBV vaccination program decreased from 12.8% to 4.8% among those born after the vaccination program (P < 0.001, chi(2) test for linear trend). Similarly, HBsAg carrier rate among female university students born before the initiation of the HBV vaccination program decreased from 8.1% to 2.7% among those born after the vaccination program (P < 0.001, chi(2) test for linear trend). Both male and female students in eastern Taiwan had the highest HBsAg carrier rate compared with the other places. Using multiple logistic regression analysis, compared with students born after July 1984, the adjusted OR of HBsAg carrier rate decreased from 3.10 for students born before June 1981 to 1.56 for students born from July 1983 to June 1984 (95% CI 1.96 - 4.91, P < 0.001; 95% CI 1.06 - 2.28, P = 0.024; respectively). CONCLUSIONS: Public vaccination provides long-lasting protection again HBV infection among the university students in Taiwan, China older than 18 years of age. There is a geographic variation of HBV infection among young adults in Taiwan, China.

Risk factors for developing metastatic infection from pyogenic liver abscesses.

OBJECTIVES: The aim of this study was to identify the risk factors for developing extra-hepatic metastases from pyogenic liver abscesses. METHODS: We conducted a retrospective study and reviewed 225 patients (age, 19-93 years) with a discharge diagnosis of pyogenic liver abscess from a large medical centre in Taiwan, between January 1995 and June 2000. Clinical data were collected from medical records. Of the 225 patients with a pyogenic liver abscess, 24 had extrahepatic metastases and were classified into the metastatic infection group; the remaining 201 were classified into the non-metastatic infection group and served as the control group. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated by exact logistic regression. RESULTS: After adjustment for age, sex, and the duration of symptoms before admission, diabetes mellitus (adjusted OR, 12; 95% CI, 3.3-67), alcoholism (adjusted OR, 5.2; 95% CI, 1.4-20), the time interval >7 days from the onset of symptoms to the time appropriate antibiotics were administered (adjusted OR, 3.9; 95% CI, 1.2-13), bacteraemia (adjusted OR, 5.4; 95% CI, 1.4-30), and infection (adjusted OR, 5.0; 95% CI, 1.1-47) were associated with the development of extra-hepatic metastases from pyogenic liver abscesses. On the other hand, fever (adjusted OR, 0.28; 95% CI, 0.089-0.92) and right upper quadrant pain/tenderness (adjusted OR, 0.091; 95% CI, 0.0020-0.50) were associated with the non-metastatic abscesses. We performed a multivariate analysis and found that diabetes mellitus (multivariate OR, 7.7; 95% CI, 2.1-29) and alcoholism (multivariate OR, 8.9; 95% CI, 2.6-30) were the independent risk factors for developing metastatic infections; yet right upper quadrant pain/tenderness (multivariate OR, 0.11; 95% CI, 0.014-0.87) was the predictor of no metastatic abscesses. CONCLUSIONS: Our data suggest that diabetes mellitus and alcoholism are significant risk factors for developing metastatic infections from pyogenic liver abscesses. These findings seem to imply that underlying conditions of the host influence the development of extra-hepatic metastases from pyogenic liver abscesses.

An iterative expanding and shrinking process for processor allocation in mixed-parallel workflow scheduling.

Parallel computation has been widely applied in a variety of large-scale scientific and engineering applications. Many studies indicate that exploiting both task and data parallelisms, i.e. mixed-parallel workflows, to solve large computational problems can get better efficacy compared with either pure task parallelism or pure data parallelism. Scheduling traditional workflows of pure task parallelism on parallel systems has long been known to be an NP-complete problem. Mixed-parallel workflow scheduling has to deal with an additional challenging issue of processor allocation. In this paper, we explore the processor allocation issue in scheduling mixed-parallel workflows of moldable tasks, called M-task, and propose an Iterative Allocation Expanding and Shrinking (IAES) approach. Compared to previous approaches, our IAES has two distinguishing features. The first is allocating more processors to the tasks on allocated critical paths for effectively reducing the makespan of workflow execution. The second is allowing the processor allocation of an M-task to shrink during the iterative procedure, resulting in a more flexible and effective process for finding better allocation. The proposed IAES approach has been evaluated with a series of simulation experiments and compared to several well-known previous methods, including CPR, CPA, MCPA, and MCPA2. The experimental results indicate that our IAES approach outperforms those previous methods significantly in most situations, especially when nodes of the same layer in a workflow might have unequal workloads.

The growth and development of children born to adolescent mothers in Taiwan.

BACKGROUND: Adolescent pregnancy carries a higher risk of adverse birth outcomes. Currently, there are very few longitudinal studies that have investigated the growth of children born to adolescents. This study explores the birth outcomes and determinants in adolescent pregnancies with subjects enrolled from the Taiwan Birth Cohort Study (TBCS). METHODS: Using the data of Wave I (6 months old), II (18 months old), and III (36 months old) of TBCS, a national sample of 19,381 pairs of mothers and their children were included for analysis. Out of these subjects, therewere560 pairs of adolescent mothers and children. Through completed field interviews with structured questionnaires, surveys with mothers or other family members, and with references to each child's birth certificate and Passport of Well-baby Care, the differences in birth outcomes, personal, pregnancy, and social profiles of the mothers were analyzed. RESULTS: A total of 560 adolescent mothers (<20 years old) and 18,821 adult mothers (20-34 years old) were included in this study. There was no significant difference between the two groups in terms of parameters of children growth and development. The numbers (proportions) of failure in milestones at 3 years old in gross motor functions, fine motor function, language, and social/personal development of children born to adolescent mothers are 13(2.32), 34(6.07), 10(1.79), and 24(4.29 %), respectively; while there are 392(2.08), 1015(5.39), 308(1.64) and 512(2.72 %) for those born to adult mothers, respectively. The risk factors of failure in children development were identified as "the mother isn't the night-time caregiver" and "family dysfunction". CONCLUSION: There was no significant difference in development at 3 years old among children born to adolescent and adult mothers.

Growth changes in infants born of adolescent mothers: Results of a national cohort study in Taiwan.

BACKGROUND: Adolescent pregnancy and childbirth are associated with increased risk and challenges for both mothers and birth outcomes. OBJECTIVE: To investigate the associations of growth change over time with parenting factors and to compare the differences between children born to adolescent and adult mothers in Taiwan. MATERIALS AND METHODS: The dataset retrieved from Taiwan birth cohort study (TBCS) was collected by interviews using structured questionnaires, birth certificate and Passport of Well-baby Care of each child. Changes in body weight, body height and head circumference from birth to 18 months, as well as other variables were assessed by statistical analysis. RESULTS: There were 4.13% births born to adolescent mothers in 2005. Higher ratios of breastfeeding and working were found among adult mothers (p<0.001). Significantly higher percentage of adolescent mothers caregave their infants up to 18 months (p<0.001). Children born to adolescent mothers were associated with statistically significant lower body weight (p<0.001), body height (p<0.001) and head circumference (p<0.001) in spite of velocity and slop of growth patterns were similar over time. Breastfeeding did not significantly affected growth rate during the first 6 months. Generalized estimated equation models showed that gender and preterm birth were predictive factors for birth outcomes (both p<0.001) and correlated to changes over time. CONCLUSION: Adolescent childbearing was associated with preterm birth and lower body weight, body height and head circumference from birth to 18 months. The changes in growth and development among children born to adolescent mothers remain to be followed and evaluated with the TBCS.

The pregnancy health and birth outcomes of women who underwent assisted reproductive technology: Results of a national survey.

BACKGROUND: There is an upward trend for parents to resort to assisted reproductive technology (ART) treatment due to delayed childbirth or birth difficulties. OBJECTIVE: This study investigates the pregnancy health and birth outcomes of women who underwent ART and analyzes the factors that influence birth weight to become<10 percentile when undergoing ART. MATERIALS AND METHODS: This study analyzed results of the first wave of the Taiwan Birth Cohort study. Through stratified systematic sampling, 24,200 mother-and-child sampling pairs were obtained from a total of 206,741 live births in Taiwan in 2005; 366 of the babies were born with the use of ART. RESULTS: During pregnancy, mothers who used ART suffered from higher risks of complication than the natural conception counterparts, including gestational diabetes mellitus (GDM), pregnancy induced hypertension (PIH), and placenta previa. Additionally, babies born through ART had poorer outcomes than the natural conception groups: the low birth weight (<2500g) was 33.1% compared to 6.4% for babies born naturally. CONCLUSION: Pregnancy health and birth outcomes of women who underwent ART were worse than those who got natural conception. Types of maternal complication among ART women included GDM, PIH, and placenta previa. Having multiple births was the most important factor that causes low birth weight in babies. The results of this study can be used as a reference for the health and care of mothers and babies who use ART.