Associations between land use and Perkinsus marinus infection of eastern oysters in a high salinity, partially urbanized estuary.

Infection levels of eastern oysters by the unicellular pathogen Perkinsus marinus have been associated with anthropogenic influences in laboratory studies. However, these relationships have been difficult to investigate in the field because anthropogenic inputs are often associated with natural influences such as freshwater inflow, which can also affect infection levels. We addressed P. marinus-land use associations using field-collected data from Murrells Inlet, South Carolina, USA, a developed, coastal estuary with relatively minor freshwater inputs. Ten oysters from each of 30 reefs were sampled quarterly in each of 2 years. Distances to nearest urbanized land class and to nearest stormwater outfall were measured via both tidal creeks and an elaboration of Euclidean distance. As the forms of any associations between oyster infection and distance to urbanization were unknown a priori, we used data from the first and second years of the study as exploratory and confirmatory datasets, respectively. With one exception, quarterly land use associations identified using the exploratory dataset were not confirmed using the confirmatory dataset. The exception was an association between the prevalence of moderate to high infection levels in winter and decreasing distance to nearest urban land use. Given that the study design appeared adequate to detect effects inferred from the exploratory dataset, these results suggest that effects of land use gradients were largely insubstantial or were ephemeral with duration less than 3 months.

Sociodemographic differences in depressed mood: results from a nationally representative sample of high school adolescents.

BACKGROUND: Research on adolescent mental health suggests that prevalence rates for depressed mood are not uniformly distributed across all populations. This study examined demographic difference in depressed mood among a nationally representative sample of high school adolescents. METHODS: The 2003 National Youth Risk Behavior Survey was utilized to examine the association between depressed mood and demographic variables. To examine demographic associations, chi-square and follow-up logistic regression models were created for the sample of high school adolescents (N = 15,214). RESULTS: Caucasians and African Americans were significantly less likely to report depressed mood when compared to Hispanics and Others. Women were also more likely than men to report depressed mood. No significant differences were observed among levels of urbanicity and age. CONCLUSIONS: An understanding of the difference in the prevalence and correlates of depressed mood among adolescents of various ethnic/racial and gender groups deserves increased attention. Given the fact that challenges with depressed mood in adolescents can be substantial and relatively unrecognized, there is an increased need to identify these adolescents early and intervene with culturally appropriate interventions.

Associations between depressed mood and clusters of health risk behaviors.

OBJECTIVES: To examine the association between depressed mood and clusters of health risk behaviors. METHODS: A nationally representative sample of adolescents (N=15,214) was utilized to construct 10 pseudocontinuous health risk behaviors. Cluster analysis was performed to group adolescents, and subsequent multivariable logistic models were created. RESULTS: Compared to non-risk takers, belonging to risk clusters significantly increased the odds of reporting depressed mood. African Americans in high-risk clusters appeared to be more vulnerable to depressed mood, when compared to remaining racial groups. CONCLUSIONS: Results suggest that adolescents engaging in multiple health-risk behaviors do so in the context of depressed mood.

Studying co-medication patterns: the impact of definitions.

PURPOSE: To show the necessity of distinguishing several patterns of drug prescribing that may lead to co-medication. It is demonstrated how these different patterns can be investigated using large databases containing pharmacy data or reimbursement data. METHODS: Two examples illustrate how the particular pattern of co-medication studied will influence the reported proportion of patients having co-medication, the use of antidepressants among people using anticonvulsants, and the use of antihistamines among people receiving penicillines. RESULTS: Depending on definition and period considered, the percentage of anticonvulsant users co-medicated with antidepressants ranged from 5.8% (95%CI 5.0%, 6.8%) to 14.5% (95%CI 13.2%, 15.9%) in 2000. Comparing 2002 with 2000, the ratio of proportions ranged from 1.3 to 2.1. The percentage of people who received penicillines and were co-medicated with antihistamines ranged from 0.5% (95%CI 0.4%, 0.6%) to 9.7% (95%CI 9.3%, 10.2%) in 2000. Comparing 2002 with 2000, the ratio of proportions ranged from 1.2 to 1.6. CONCLUSION: The co-medication patterns investigated yielded clinical as well as statistically significant different estimates. The estimates differed up to a factor 2.5 for the drugs usually prescribed for long periods, and a factor 12 for drugs prescribed for short periods. Hence, we propose to distinguish the patterns 'co-prescribing', 'concomitant medication,' and 'possibly concurrent medication.' The research question determines the co-medication pattern of interest, and the drug and disease under study determine the time window.

Survival instantaneous log-odds ratio from empirical functions.

The objective of this work is to introduce a new method called the Survivorship Instantaneous Log-odds Ratios (SILOR); to illustrate the creation of SILOR from empirical bivariate survival functions; to also derive standard errors of estimation; to compare results with those derived from logistic regression. Hip fracture, AGE and BMI from the Third National Health and Nutritional Examination Survey (NHANES III) were used to calculate empirical survival functions for the adverse health outcome (AHO) and non-AHO. A stable copula was used to create a parametric bivariate survival function, that was fitted to the empirical bivariate survival function. The bivariate survival function had SILOR contours which are not constant. The proposed method has better advantages than logistic regression by following two reasons. The comparison deals with (i) the shapes of the survival surfaces, S(X1, X2), and (ii) the isobols of the log-odds ratios. When using logistic regression the survival surface is either a hyper plane or at most a conic section. Our approach preserves the shape of the survival surface in two dimensions, and the isobols are observed in every detail instead of being overly smoothed by a regression with no more than a second degree polynomial. The present method is straightforward, and it captures all but random variability of the data.

Comorbidity between and risk factors for severe hearing and memory impairment in older Americans.

OBJECTIVE: Comorbidities complicate our understanding of impairments and their risk factors. The objective of the current study was to assess the comorbidity between hearing impairment (HI) and memory impairment (MI) in older Americans and to assess to what extent they share common risk factors. METHOD: Data were examined from 5252 participants aged 65 years or older from the Third National Health and Nutrition Examination Survey (1988-1994). RESULTS: The prevalence of HI and MI was 21.4 (SE 0.8)% and 8.3 (0.6)%, respectively, but the prevalence of concurrent impairment was only 2.1 (0.2)%. African Americans had higher odds of MI than whites (OR=3.75, 95% CI: 2.81, 5.00), but not of HI (OR=0.62, 95% CI: 0.42, 0.91). Leisure physical activity was associated with lower odds of MI, good lung function was associated with lower odds of HI, and moderate alcohol use was associated with lower odds of both HI and MI. Compared with individuals free of HI, the OR of MI was 1.07 (95% CI: 0.78, 1.47) for individuals with HI. CONCLUSION: Although prevalence was relatively high, comorbidity was surprisingly low, and the two impairments were not significantly associated. In addition to age, other factors appear to play critical but different roles in the development of these impairments.

Adolescent distinctions between quality of life and self-rated health in quality of life research.

BACKGROUND: In adult quality of life (QOL) research, the QOL construct appears to differ from self-rated health status. Although increased QOL continues to be recognized as an important outcome in health promotion and medical intervention, little research has attempted to explore adolescent perceptual differences between self-rated health and QOL. METHODS: Correlational analyses were performed between self-rated health, physical health days and mental health days, and QOL. Data were collected from two different public high school adolescent samples during two different time periods (1997 & 2003) in two different geographic regions in the USA (a southern & midwestern state) with two different sample sizes (N = 5,220 and N = 140, respectively) using the CDC Youth Risk Behavior Survey (YRBS). The Centers for Disease Control and Preventions' health-related quality of life scale (HRQOL) provided estimates of self-rated health, physical health days and mental health days, and QOL. RESULTS: All correlation coefficients were significant in both samples (p < or = .0001), suggesting sample size was not a contributing factor to the significant correlations. In both samples, adolescent QOL ratings were more strongly correlated with the mean number of poor mental health days (r = .88, southern sample; r = .89, midwestern sample) than with the mean number of poor physical health days (r = .75, southern sample; r = .79, midwestern sample), consistent with adult QOL research. However, correlation coefficients in both samples between self-rated health and the mean number of poor physical health days was slightly smaller (r = .24, southern, r = .32, midwestern) than that between self-rated health and the mean number of poor mental health days (r = .25, southern, r = .39 midwestern), which is contrary to adult QOL research. CONCLUSION: Similar to adults, these results suggest adolescents are rating two distinct constructs, and that self-rated health and QOL should not be used interchangeably. QOL, in the context of public high school adolescents, is based largely upon self-reported mental health and to a lesser extent on self-reported physical health. Conversely, although self-reported mental health and self-reported physical health both contribute significantly to adolescent self-rated health, mental health appears to make a greater contribution, which is contrary to observations with adults. Health promoting efforts for adolescents may need to focus more on mental health than physical health, when considering population needs and type of micro or macro intervention.

Adolescent health-related quality of life and perceived satisfaction with life.

PURPOSE: To explore the relationship between perceived satisfaction with life and health-related quality of life (HRQOL) in a state-wide sample of 13-18-year-old adolescents (n = 4914) in South Carolina, USA. METHODS: Questions were added to the self-report Centers for Disease Control (CDC) Youth Risk Behavior Survey (YRBS) asking about perceived life satisfaction in six domains (self, family, friends, living environment, school, and overall) and HRQOL (self-rated health; and the number of poor physical health days, poor mental days, and activity limitation days during the past 30 days). RESULTS: Adjusted logistic regression analyses and multivariate models constructed separately revealed that self-rated health, poor physical days (past 30 days), poor mental health days (past 30 days), and activity limitation days (past 30 days) were significantly related (p < 0.05) to reduced life satisfaction, regardless of race or gender. Moreover, as the number of reported poor health days increased, the greater the odds of reporting life dissatisfaction. CONCLUSIONS: This is the first study to document the relationship between poor physical health and perceived life satisfaction. This adds to the mounting evidence that life satisfaction is related to a variety of adolescent health behaviors and that life satisfaction may add additional information in longitudinal databases that track adolescent health because it appears to be related to HRQOL.

A critique of the use of hormesis in risk assessment.

There are severe problems and limitations with the use of hormesis as the principal dose-response default assumption in risk assessment. These problems and limitations include: (a) unknown prevalence of hormetic dose-response curves; (b) random chance occurrence of hormesis and the shortage of data on the repeatability of hormesis; (c) unknown degree of generalizability of hormesis; (d) there are dose-response curves that are not hormetic, therefore hormesis cannot be universally generalized; (e) problems of post hoc rather than a priori hypothesis testing; (f) a possible large problem of 'false positive' hormetic data sets which have not been extensively replicated; (g) the 'mechanism of hormesis' is not understood at a rigorous scientific level; (h) in some cases hormesis may merely be the overall sum of many different mechanisms and many different dose-response curves - some beneficial and some toxic. For all of these reasons, hormesis should not now be used as the principal dose-response default assumption in risk assessment. At this point, it appears that hormesis is a long way away from common scientific acceptance and wide utility in biomedicine and use as the principal default assumption in a risk assessment process charged with ensuring public health protection.

Evaluating the performance of the Centers for Disease Control and Prevention core Health-Related Quality of Life scale with adolescents.

OBJECTIVE: The purpose of this study was to evaluate the performance of the Centers for Disease Control and Prevention's core Health-Related Quality of Life (HRQOL) scale using data from 5,520 public high school students. METHODS: The 1997 South Carolina Youth Risk Behavior Survey was the source of data. Chi-square analysis was applied to assess scale construct validity. Adjusted multiple logistic regression with selected tobacco and substance use variables was used to assess known-groups validity of the scale's Healthy Days index (items regarding poor physical and mental health days during the past 30 days). RESULTS: Construct validity was supported for the core HRQOL scale by the associations between self-perceived health and physical health, mental health, and activity limitation days. A greater number of poor physical health days, poor mental health days, or activity limitation days was associated with poorer self-perceived health (p<0.0001); however, correlation coefficients for the associations between self-perceived health and physical health days (r=0.24; p<0.001), self-perceived health and mental health days (r=0.26; p<0.0001), and self-perceived health and activity limitation days (r=0.23; p<0.0001), although significant, were low in magnitude. Logistic regression analyses conducted with the Healthy Days index revealed significant (p<0.05) HRQOL differences between users and non- users of tobacco and other substance use variables. As hypothesized, as the usage of each substance increased, reported poor HRQOL days increased, supporting the known- groups validity of the scale. CONCLUSIONS: This study provides preliminary evidence that the HRQOL scale items are valid and potentially useful for adolescent surveillance. The results, however, are mixed regarding the inclusion of self-perceived health as a measure of HRQOL for adolescents, given the low correlation coefficients for the associations between self-perceived health and the other HRQOL scale items. These results suggest that adolescents may be rating two separate dimensions of health when rating their self-perceived health and HRQOL. Further research is needed to confirm these findings in different adolescent populations.

Correlates of body mass index, weight goals, and weight-management practices among adolescents.

The study examined associations among physical activity, cigarette smoking, body mass index, perceptions of body weight, weight-management goals, and weight-management behaviors of public high school adolescents. The CDC Youth Risk Behavior Survey provided a cross-sectional sample (n = 3,089) of public high school students in South Carolina. Logistic regression models were constructed separately for four race-gender groups. Adjusted odds ratios and 95% confidence intervals were calculated to determine the magnitude of associations. Based on self-reported height and weight, 13% of students were overweight, while 15% were at risk for becoming overweight. However, 42% of students were trying to lose weight, and 22% were trying to maintain current weight. Female students were less likely than male students to be overweight, but more likely to be attempting to lose weight. Extreme weight control practices were reported by 27% of the sample. Among Black females trying to lose weight, positive associations were observed for strengthening exercises (OR = 1.55), but that relationship was associated inversely in Black males (OR = .600). Among White females, attempted weight loss was associated with strengthening exercises (OR = 1.72) and cigarette smoking (OR = 1.54). For White males, attempted weight loss was associated positively with vigorous exercise (OR = 1.41) and inversely related to moderate exercise (OR = .617). Effective weight-management practices for adolescents should focus on appropriate eating behaviors, physical activity, and low-fat/calorie diets. Multicomponent weight management interventions should be conducted within a coordinated school health framework.

Physical activity behaviors and perceived life satisfaction among public high school adolescents.

This study explored relationships between perceived life satisfaction and physical activity behaviors in a statewide sample of adolescents in South Carolina (n = 4,758) using the CDC Youth Risk Behavior Survey (YRBS) and the Brief Multidimensional Student Life Satisfaction Scale (BMSLSS). Adjusted logistic regression analyses and multivariate models constructed separately revealed significant race by gender results. Not exercising for 20 minutes over the past 7 days (sweating and hard breathing), not performing stretching exercising (past 7 days), not exercising to strengthen or tone muscles (past 7 days), spending < 20 minutes actually exercising or playing sports in PE class, not playing on sport teams run by school, and not playing on sport teams run by outside school organizations were associated (p = .05) with reduced life satisfaction for specific race/gender groups. Results suggest implications for school and community-based physical activity programs. Future research should consider measures of life satisfaction as a component of comprehensive assessments of adolescent physical activity behaviors in fieldwork, research, and program evaluation.

Brief multidimensional students' life satisfaction scale: sex, race, and grade effects for a high school sample.

Preliminary normative data for the total score of the Brief Multidimensional Students' Life Satisfaction Scale were collected from 5,034 adolescents in Grades 9 through 12 at public high schools in South Carolina. The statistically significant mean differences by race were of small magnitude. Mean total scores did not differ by sex or grade in school.

Dieting behaviors, weight perceptions, and life satisfaction among public high school adolescents.

Relationships among perceived life satisfaction, perceptions of body weight, and dieting behaviors were examined in a statewide cross-sectional study of public high school adolescents in South Carolina (N = 5,032). The Centers for Disease Control (CDC) Youth Risk Behavior Survey and the Brief Multidimensional Students' Life Satisfaction Scale were utilized for this study. Adjusted logistic regression analyses and multivariate models constructed separately (via SUDAAN), revealed that perceptions of overweight, perceptions of underweight, having dieted to lose weight, having vomited or used laxatives to lose weight, and taking diet pills were significantly related (p < .05) to reduced life satisfaction for adolescents. Differences in dieting behavior and perceptions of weight were demonstrated across gender and race. Measures of life satisfaction as a component of comprehensive assessments of adolescent weight management and healthy eating behaviors in clinic, fieldwork, research, and program-evaluation efforts should be considered.

Risk factors and behaviors associated with adolescent violence and aggression.

OBJECTIVE: To explore risk factors and behaviors associated with aggressive and violent behaviors among adolescents. METHODS: A comprehensive review of research literature from various disciplines associated with improving the health and well-being of adolescents. RESULTS: Risk factors and behaviors associated with adolescent aggression and violence are discussed via 6 major factor categories: individual, family, school/academic, peer-related, community and neighborhood, and situational. CONCLUSION: Adolescent aggression and violence develops and manifests within a complex constellation of factors. Prevention intervention efforts should be theory based, multicomponent, and multisystem; they should begin in middle school and continue into high school with a comprehensive evaluation design.

Risk behavior data analysis: ordinal or dichotomous the choice is yours.

OBJECTIVE: To demonstrate the differences of 2 approaches to data analysis. METHODS: Using the South Carolina YRBS data, study focused on contingency tables and ANOVA. Additive chi squares are utilized to illustrate information loss when collapsing a contingency table. Odds ratios are derived from contingency tables or logistic regression. Means are utilized in ANOVA. Five measures of life satisfaction were summed to create a pseudo-continuous response variable that was subsequently trichotomized. All predictors are dichotomized risk variables. RESULTS: Chi squares from subtables added exactly to that of the original table measuring lost information. ANOVA conveyed the same clinical message. CONCLUSION: Clinically relevant conclusions might be the same even when drawn from any of several different analyses of the same risk-behavior data.

Differences in diet quality among fourth and seventh grade public school students in South Carolina.

The purpose of this study was to compare various aspects of diet quality between fourth graders and seventh graders. Consumption in each food group and food variety pattern suggested that dietary quality of fourth graders and seventh graders were different. Fourth graders showed "better" dietary behaviors than seventh graders with some variations among food groups and differences regarding gender. Importantly, it should be noted by the health care community that diet quality tends to decline with the progression from childhood to early adolescence. These same concerns are mentioned in the previous paper, i.e., the declining quality of diet with increased age in moving from childhood to adolescence. Specific areas that should be targeted for improvement were identified. The information obtained from this study suggests the need for renewed efforts by physicians, health educators, nutritionists, and policy makers to improve the diet quality of children and adolescents. In addition, this information is vital for formulating the appropriate and effective private provider and public health interventions and prevention initiatives to improve the health and wellness of South Carolina youth as they progress from childhood to adolescence into adulthood.

Using path analysis to examine adolescent suicide attempts, life satisfaction, and health risk behavior.

This study determined if differences existed between four race/gender groups in regard to attempted suicide among a randomly selected, cross-sectional population of 4,565 public high school students in South Carolina. A modified Youth Risk Behavior Survey was designed to gather information on quality of life, life satisfaction, and six risk-behavior categories. Data first were analyzed using logistic regression analysis and subsequently analyzed using path analysis. Results suggest several independent variables (feelings of intimidation, alcohol and cocaine use, self-perceptions of mental health, self-perceptions of body weight, dieting practices, bulimic episodes, and physical and sexual abuse) were associated significantly (p < .01) with adolescent attempted suicide either directly or indirectly through mediating variables. Significant associations among risk behaviors, mediating variables, and self-reported attempted suicide varied across the four race/gender groups, indicating a need to further study differences noticed in each race/gender scheme.

Relationship between perceived life satisfaction and adolescents' substance abuse.

PURPOSE: To explore the relationship between perceived global life satisfaction and selected substance use behaviors among 5032 public high school students. METHODS: The 1997 South Carolina Youth Risk Behavior Survey substance abuse and life satisfaction variables were used. An adjusted polychotomous logistic regression analysis utilizing SAS/SUDAAN, revealed a significant race/gender interaction. Subsequent multivariate models were constructed individually for four race/gender groups. Adjusted odds ratios and 95% confidence intervals were calculated to assess the magnitude of risk for selected substance abuse behaviors and their association with reduced global life satisfaction. RESULTS: Cigarette smoking, chewing tobacco, marijuana, cocaine, regular alcohol use, binge drinking, injection drug, and steroid use were significantly (p < .05) associated with reduced life satisfaction for specific race/gender groups (white males; black males; white females; and black females). In addition, age (< or = 13 years) of first alcohol drink, first marijuana use, first cocaine use, and first cigarette smoked were also significantly (p < .05) associated with reduced life satisfaction. CONCLUSION: Longitudinal studies are needed to determine whether dissatisfaction with life is a consequence or determinant of substance abuse behavior for adolescents.