Biomedical subjects

Rusan Chen

Publications and source records attributed to Rusan Chen.

13 recordsLinked to original sources

PubMed2006

Demographic risk factors, mediators, and moderators in youths' diabetes metabolic control.

BACKGROUND: Socioeconomic status (SES) is one of the most frequently identified and potent predictors of disease morbidity and mortality. It also predicts diabetes care and metabolic control, yet it is often confounded with parental marital status and ethnicity in pediatric samples. PURPOSE: Key demographic risk factors for poorer metabolic control in adolescents with type I diabetes are examined to distinguish their relative effects, along with disease care mediators and family environment moderators. METHODS AND RESULTS: When SES, ethnicity, and marital status are considered simultaneously with path analysis, living with married biological parents is the sole predictor of better metabolic control in a predominantly middle-class sample. Specifically, adolescents who lived with their biologic parents had glycosylated hemoglobin levels that were approximately .5% lower on average than those who lived in alternative family arrangements (i.e., blended and single-parent families). More frequent meals and snacks and more blood glucose monitoring mediates this effect. Under favorable conditions of greater familial harmony, children from married biologic families experience a stronger beneficial health effect, with average glycohemoglobin levels that are approximately .81% lower in less conflicted families and .62% lower in more cohesive families. CONCLUSIONS: In toto, marital status eclipsed the well known effects of SES in the prediction of metabolic control in a primarily middle-class sample of children with diabetes. The 8.0% average glycohemoglobin level of youths from married biologic families is similar to that of intensively treated adolescents in the Diabetes Control and Complications Trial and, if maintained, should be associated with clinically significant reductions in disease complications.

Adolescent↗

PubMed2006

Arsenic cancer risk confounder in southwest Taiwan data set.

Quantitative analysis for the risk of human cancer from the ingestion of inorganic arsenic has been based on the reported cancer mortality experience in the blackfoot disease (BFD) -endemic area of southwest Taiwan. Linear regression analysis shows that arsenic as the sole etiologic factor accounts for only 21% of the variance in the village standardized mortality ratios for bladder and lung cancer. A previous study had reported the influence of confounders (township, BFD prevalence, and artesian well dependency) qualitatively, but they have not been introduced into a quantitative assessment. In this six-township study, only three townships (2, 4, and 6) showed a significant positive dose-response relationship with arsenic exposure. The other three townships (0, 3, and 5) demonstrated significant bladder and lung cancer risks that were independent of arsenic exposure. The data for bladder and lung cancer mortality for townships 2, 4, and 6 fit an inverse linear regression model (p < 0.001) with an estimated threshold at 151 microg/L (95% confidence interval, 42 to 229 microg/L) . Such a model is consistent with epidemiologic and toxicologic literature for bladder cancer. Exploration of the southwest Taiwan cancer mortality data set has clarified the dose-response relationship with arsenic exposure by separating out township as a confounding factor. Key words: arsenic, blackfoot disease, bladder cancer, cancer risk, confounder, dose-response relationship, southwest Taiwan, threshold model.

Arsenic↗

PubMed2005

Predictors of youth diabetes care behaviors and metabolic control: a structural equation modeling approach.

OBJECTIVE: To empirically test a biopsychosocial model of predictors of youth diabetes care behaviors and metabolic control. METHODS: A cross-sectional multisite study of youths (N = 222) with T1D (mean age = 12.6) used structural equation modeling to examine interrelations among predictors, with follow-up analyses of covariance (ANCOVAs). RESULTS: Youths' memory skills related to diabetes knowledge which, along with self-efficacy and age, was associated with greater youth responsibility that in turn predicted poorer self-care behaviors. Less frequent/briefer exercise and less frequent blood glucose monitoring/eating were found; the latter directly related to poorer metabolic control. Behavior problems also were associated directly with poorer metabolic control. A parsimonious model found memory directly related to blood glucose testing. CONCLUSIONS: Continued parental supervision of adolescents, along with monitoring diabetes knowledge and efficacy, may help optimize transfer of diabetes care from parents to youths. Behavior problems warrant immediate attention because of their direct and adverse relation to metabolic control.

Adolescent↗

PubMed2005

Pediatric parenting stress among parents of children with type 1 diabetes: the role of self-efficacy, responsibility, and fear.

OBJECTIVE: Parents of children with type 1 diabetes are crucial to promoting positive disease adaptation and health outcomes among these youngsters, yet this success may come at some consequence to parents' own well-being. Little research has examined the stress faced by parents, or explored the psychological and behavioral correlates of their stress. METHODS: One hundred and thirty-four parents of children with type 1 diabetes completed measures of diabetes self-efficacy, responsibility for diabetes management, fear of hypoglycemia, and a recently developed measure of pediatric parenting stress (the Pediatric Inventory for Parents [PIP]; R. Streisand, S. Braniecki, K. P. Tercyak, & A. E. Kazak, 2001). RESULTS: Bivariate analyses suggest that pediatric parenting stress is multifaceted; the frequency of parenting stress is negatively related to child age and family socioeconomic status and positively related to single parent status and regimen status (injections vs. insulin pump). Difficulty of parenting stress is negatively related to child age and positively related to regimen status. In multivariate analyses, a significant portion of the variance in stress frequency (32%) and difficulty (19%) are associated with parent psychological and behavioral functioning, including lower self-efficacy, greater responsibility for diabetes management, and greater fear of hypoglycemia. CONCLUSIONS: Each area of parent functioning associated with pediatric parenting stress is amenable to behavioral intervention aimed at stress reduction or control and improvement of parent psychological and child-health outcomes.

Adult↗

PubMed2005

The effects of the going places program on early adolescent substance use and antisocial behavior.

This study evaluated the effects of a school-based intervention on growth trajectories of smoking, drinking, and antisocial behavior among early adolescents. Seven middle schools were randomized to intervention or comparison conditions and students in two successive cohorts (n = 1484) provided five waves of data from sixth to ninth grade. The Going Places Program, included classroom curricula, parent education, and school environment components. Latent growth curve analyses demonstrated significant treatment group effects, including reducing increases in friends who smoke, outcome expectations for smoking, and smoking progression, but had non-significant effects on drinking or antisocial behavior. The Going Places Program was effective in preventing increases in smoking progression, but its efficacy as a more cross-cutting problem behavior preventive intervention was not confirmed.

Adolescent↗

PubMed2005

Psychosocial predictors of smoking trajectories during middle and high school.

AIMS: Little is known about the heterogeneity in and risk factors associated with trajectories of smoking during adolescence. This study aimed to (1) identify smoking trajectories empirically and (2) identify risk factors for trajectory group membership. DESIGN: Latent growth mixture models were used to identify population smoking trajectories, and logistic regression was used to estimate risk factors for group membership. SETTING: The participants were drawn from seven middle schools in a Maryland school district. PARTICIPANTS: Participants consisted of 1320 6th graders who were followed to the 9th grade. MEASUREMENTS: Measurements of smoking risk factors were made in the fall of 6th grade and smoking stage was assessed on five different occasions between the fall of 6th and 9th grades. FINDINGS: Five distinct smoking trajectories were identified. Overall, being female, having friends who smoked, deviance acceptance and outcome expectations were associated with an increased likelihood of being an intender, delayed escalator, early experimenter and early user compared to a never smoker. Additionally, comparisons with never smokers revealed unique identifiers for intenders, early experimenters and early users, but not delayed escalators. CONCLUSIONS: There is much heterogeneity in the manner in which middle-schoolers progress from having no intention of smoking to becoming smokers. Implications for prevention programs are discussed.

Adolescent↗

PubMed2005

Impact analysis and mediation of outcomes: the Going Places program.

The purpose of the study was to evaluate the impact of the Going Places Program and mediation of treatment effects. Seven middle schools were randomized to intervention or comparison conditions and students (n=1,320) in two successive cohorts provided five waves of data from sixth through eighth grade. The Going Places Program included classroom curriculum, parent education, and school environment components. Latent growth curve analyses demonstrated significant treatment group effects on outcome expectancies, friends who smoke, and smoking. Friends who smoke mediated the program effect on adolescents' smoking progression. The protective effect of the Going Places Program on smoking progression was due in part to the prevention of increases in friends who smoke.

Adolescent↗

PubMed2005

Latent growth curve analyses of parent influences on drinking progression among early adolescents.

OBJECTIVE: The nature of parent influences on early adolescent substance use was examined. METHOD: Latent growth curve analyses were used to examine data on a sample of 2,453 adolescents from seven middle schools who were randomized to a problem behavior prevention program or a control condition and were assessed a total of five times during sixth to ninth grade. RESULTS: Whereas the growth in the number of friends who drink was positively associated with adolescent drinking, parental involvement, monitoring and expectations over time provided direct protective effects against drinking progression and indirect effects by limiting increases in the number of friends who drink. CONCLUSIONS: The results provide evidence in a sample of early adolescents that parenting behavior--including involvement, monitoring and expectations--protected against progression in drinking directly as well as indirectly by limiting growth in the number of friends who drink.

Adolescent↗

PubMed2004

Latent growth curve analyses of peer and parent influences on smoking progression among early adolescents.

Social influences on smoking uptake were examined in latent growth curve analyses of data from 1,320 youths assessed 5 times during 6th to 9th grade. Initial smoking stage predicted increases in number of friends who smoked, indicating selection; however, initial number of friends who smoked did not predict smoking stage progression, indicating no significant effect of socialization. Associations over time among smoking stage progression, affiliation with friends who smoke, and parenting behaviors were significant, suggesting dynamic, reciprocal relationships. Parental involvement, monitoring, and expectations provided direct protective effects against smoking progression as well as indirect effects, by limiting increases in number of friends who smoke. These results are consistent with the peer selection hypothesis, confirm the powerful association over time of social influences with smoking, and provide the first evidence that parenting behavior may protect against smoking progression by limiting increases in number of friends who smoke.

Adolescent↗

PubMed2004

Factor structure of the Wide Range Assessment of Memory and Learning (WRAML) in children with insulin dependent diabetes mellitus (IDDM).

Maximum likelihood confirmatory factor analysis was performed with the Wide Range Assessment of Memory and Learning (WRAML) for a clinical sample of 246 children with insulin-dependent diabetes mellitus (IDDM). Consistent with previous literature examining the factor structure of the WRAML, findings supported the validity of a three-factor model including Verbal Memory, Visual Memory, and Attention/Concentration (AC) factors for this clinical sample. However, in contrast to previous factor analytic research, results also supported the validity of an alternative two-factor model consisting of a combined modality Memory/Learning (ML) factor and an AC factor. While the results suggest that the three-factor solution may provide an adequate characterization of memory and learning in the majority of this sample of children with IDDM, it appears that certain groups of children with IDDM, particularly those children with early disease onset and those who experience hypoglycemic seizures, may exhibit a specific profile of differences that may result in a lack of differentiation between the verbal and visual modalities.

Adolescent↗

PubMed2004

Memory matters: developmental differences in predictors of diabetes care behaviors.

OBJECTIVE: Longitudinal research shows that pediatric type 1 diabetes can result in verbal memory difficulties, yet the role of memory in the daily management of this or any other chronic illness has not been evaluated. METHODS: Verbal memory measures from two well-standardized tests were administered to 224 youths with type 1 diabetes, aged 9 to 17. Twenty-four-hour recall interviews conducted separately with mothers and their children assessed diabetes care behaviors. RESULTS: Rote verbal memory predicted blood glucose testing frequency for adolescents but not for preadolescents; and when combined with ethnicity, socioeconomic status, and age, rote verbal memory accounted for 27.6% of the variance, p <.001. Quantitative verbal working memory--along with ethnicity, socioeconomic status, and age, p <.01--accounted for 33.7% of the variance in predicting carbohydrate calories for older adolescents. CONCLUSIONS: Memory, in addition to demographic factors, is a significant predictor of some of the central self-care behaviors involved in diabetes management. However, memory only predicts diabetes management for older adolescents, who have greater self-care responsibility.

Adolescent↗

PubMed2004

Heart rate monitoring as a measure of physical activity in children.

PURPOSE: Using a larger sample and broader range of activities than most previous investigations of HR monitoring, this study examined the need for individual calibration of the HR-VO2 prediction equation, the effect of including low-intensity activities when establishing the HR-VO2 equation, comparisons of different methods for calculating HR-VO2 prediction equations for maximum energy expenditure (EE) variance, and the effect of these different methods when applied to free-living HR data. METHODS: Forty-three children ages 8 to 12 completed laboratory assessments of the relationship between HR and VO2. Different methods of estimating daily EE were applied to free-living HR data collected from 37 of these children. RESULTS: There was significant individual variation in the HR-VO2 prediction equations. HR monitoring predicted VO2 during low-intensity activities, below most established cut points. Individual differences persisted during both high- and low-intensity activities. Although a HR-VO2 prediction equation generated from the group accounted for 85% of the variance in EE, significant improvements in prediction were achieved with individualized HR-VO2 prediction equations that took into account low-intensity activity levels. CONCLUSION: Generic equations derived from group data may be suitable for some applications. However, for investigators requiring more precision, individual HR-VO2 equations significantly improve prediction.

Child↗

PubMed2003

An SAS/IML procedure for maximum likelihood factor analysis.

Maximum likelihood factor analysis (MLFA), originally introduced by Lawley (1940), is based on a firm mathematical foundation that allows hypothesis testing when normality is assumed with large sample sizes. MLFA has gained in popularity since Jöreskog (1967) implemented an iterative algorithm to estimate parameters. This article presents a concise program using matrix language SAS/IML with the optimization subroutine NLPQN to obtain MLFA solutions. The program is pedagogically useful because it shows the step-by-step computational processes for MLFA, whereas almost all other statistical packages for MLFA are in "black boxes." It is also demonstrated that this approach can be extended to other multivariate methods requiring numerical optimizations, such as the widely used structural equation modeling. Researchers may find this program useful in conducting Monte Carlo simulation studies to investigate the properties of multivariate methods that involve numerical optimizations.

Algorithms↗