Biomedical subjects

Peter J Hannan

Publications and source records attributed to Peter J Hannan.

At least 19 recordsLinked to original sources

PubMed2007

Sizing a trial to alter the trajectory of health behaviours: methods, parameter estimates, and their application.

Group-randomized trials often involve repeat observations on the same participants. When there are no more than two observations from each participant, standard mixed-model regression methods for a pretest-posttest design can be used. When there are more than two observations from each participant, random coefficients models may be useful. This paper describes the random coefficients analysis appropriate to data from an extended nested cohort design and presents the methods for power analysis and sample size calculations based on that analysis. We provide estimates for the parameters required for those calculations for a number of adolescent health behaviours. We also show how the estimates can be used to plan a future trial.

Adolescent↗

PubMed2007

Is dieting advice from magazines helpful or harmful? Five-year associations with weight-control behaviors and psychological outcomes in adolescents.

OBJECTIVE: The purpose of this study was to evaluate the association between frequent reading of magazine articles about dieting/weight loss and weight-control behaviors and psychological outcomes 5 years later in a sample of adolescents. PARTICIPANTS AND METHODS: Data are from Project EAT (Eating Among Teens), a 5-year longitudinal study of eating, activity, weight, and related variables in 2516 middle and high school students. In 1999 (time 1), participants completed surveys and had their height and weight measured. In 2004 (time 2), participants were resurveyed. RESULTS: For female adolescents, the frequency of healthy, unhealthy, and extreme weight-control behaviors increased with increasing magazine reading after adjusting for time 1 weight-control behaviors, weight importance, BMI, and demographic covariates. The odds of engaging in unhealthy weight-control behaviors (such as fasting, skipping meals, and smoking more cigarettes) were twice as high for the most frequent readers compared with those who did not read magazine articles about dieting and weight loss. The odds of using extreme weight-control behaviors (such as vomiting or using laxatives) were 3 times higher in the highest frequency readers compared with those who did not read such magazines. There were no significant associations for either weight-control behaviors or psychological outcomes for male adolescents. CONCLUSIONS: Frequent reading of magazine articles about dieting/weight loss strongly predicted unhealthy weight-control behaviors in adolescent girls, but not boys, 5 years later. Findings from this study, in conjunction with findings from previous studies, suggest a need for interventions aimed at reducing exposure to, and the importance placed on, media messages regarding dieting and weight loss.

Adolescent↗

PubMed2006

V.I.K. (Very Important Kids): a school-based program designed to reduce teasing and unhealthy weight-control behaviors.

The purpose of this study was to evaluate the feasibility and effectiveness of V.I.K. (Very Important Kids), a school-based, multi-component intervention designed to prevent teasing and unhealthy weight-control behaviors among fourth through sixth grade students. The effectiveness of the V.I.K. intervention was evaluated using a pre-post quasi-experimental design with one school assigned to each condition: intervention and assessment-only control. Data were collected at baseline and at 8-month post-test among 63 students at the intervention school and 57 students at the control school. The V.I.K. intervention included an after-school program, a theater program, school environment components and a family component. Process data suggest that the V.I.K. program can feasibly be implemented within a school setting and can effectively engage students, school staff and parents. Analysis of impact data revealed that the percentage of students reporting being teased decreased significantly in the intervention school relative to the control school, after controlling for baseline levels of teasing, body mass index z score and demographic factors (odds ratio = 0.22; 95% confidence interval = 0.06, 0.88; P = 0.03). These findings provide promising evidence that multi-component, school-based interventions may effectively reduce teasing in elementary schools. Future research of interventions aimed at preventing teasing using a larger sample of schools is warranted.

Aggression↗

PubMed2006

Overweight status and weight control behaviors in adolescents: longitudinal and secular trends from 1999 to 2004.

BACKGROUND: This study examined 5-year longitudinal and secular trends in weight status and the use of healthy and unhealthy weight control behaviors in adolescents. METHODS: Project EAT-II followed 2516 adolescents from Minnesota longitudinally from 1999 to 2004. The population included two cohorts allowing for the observation of transitions from early to middle adolescence (junior high school to high school) and from middle to late adolescence (high school to post-high school). RESULTS: The prevalence of overweight (females: 28.7%; males: 28.0%) was high in early adolescence and remained high throughout adolescence. In females, between early and middle adolescence, there were steep longitudinal increases in the use of unhealthy weight control behaviors (48.6% to 58.8%, P = 0.001) and extreme weight control behaviors (9.4% to 17.9%, P < 0.001), and between middle and late adolescence, extreme weight control behaviors increased from 14.5% to 23.9% (P < 0.001). In males, extreme weight control behaviors doubled from middle to late adolescence (3.4% to 6.3%, P = 0.023). Use of diet pills doubled from 7.5% to 14.2% from 1999 to 2004 (P = 0.004) in high school females. One fifth (19.9%) of females in late adolescence reported taking diet pills. CONCLUSIONS: Overweight status and unhealthy weight control behaviors in adolescents are major public health concerns that warrant interventions addressing both problems.

Adolescent↗

PubMed2006

Electrocardiographic findings and incident coronary heart disease among participants in the Atherosclerosis Risk in Communities (ARIC) study.

The associations of many electrocardiographic (ECG) abnormalities at rest with incident coronary heart disease (CHD) are not completely established, and whether individual ECG abnormalities convey similar risk across gender and race is uncertain. We studied the independent association of several ECG findings with incident CHD, testing for effect modification by gender and race, in a large, population-based, prospective cohort study. Findings from the baseline 12-lead electrocardiograms in 1987 to 1989 were classified according to the Minnesota Code in 12,987 black and white men and women, aged 45 to 64 years, who were initially free of CHD and the use of specific cardiac medications. The incidence of CHD was ascertained through 2000. After adjustment for multiple cardiovascular risk factors, the ECG findings that had the highest hazard rate ratios (HRRs) for incident CHD, when considered singly, were left ventricular hypertrophy with ST-T strain pattern in white men (HRR 6.50) and in black women (HRR 2.31) and, in the whole cohort, major (HRR 2.27) and minor (HRR 2.47) ST depression and major T-wave abnormalities (HRR 2.12). Statistically significant associations were also found in the whole cohort for minor Q waves and left ventricular hypertrophy by the Cornell definition, but not for a prolonged QTc interval, major ventricular conduction defects, or ST elevation. In conclusion, several 12-lead ECG findings were independently associated with incident CHD in middle-aged adults. With only a few exceptions, the associations were similar for blacks and whites.

Black People↗

PubMed2006

A comparison of permutation and mixed-model regression methods for the analysis of simulated data in the context of a group-randomized trial.

Our first purpose was to determine whether, in the context of a group-randomized trial (GRT) with Gaussian errors, permutation or mixed-model regression methods fare better in the presence of measurable confounding in terms of their Monte Carlo type I error rates and power. Our results indicate that given a proper randomization, the type I error rate is similar for both methods, whether unadjusted or adjusted, even in small studies. However, our results also show that should the investigator face the unfortunate circumstance in which modest confounding exists in the only realization available, the unadjusted analysis risks a type I error; in this regard, there was little to distinguish the two methods. Finally, our results show that power is similar for the two methods and, not surprisingly, better for the adjusted tests. Our second purpose was to examine the relative performance of permutation and mixed-model regression methods in the context of a GRT when the normality assumptions underlying the mixed model are violated. Published studies have examined the impact of violation of this assumption at the member level only. Our findings indicate that both methods perform well when the assumption is violated so long as the ICC is very small and the design is balanced at the group level. However, at ICC>or=0.01, the permutation test carries the nominal type I error rate while the model-based test is conservative and so less powerful. Binomial group- and member-level errors did not otherwise change the relative performance of the two methods with regard to confounding.

Computer Simulation↗

PubMed2006

Does body satisfaction matter? Five-year longitudinal associations between body satisfaction and health behaviors in adolescent females and males.

PURPOSE: This study addresses the question, "Does body satisfaction matter?" by examining longitudinal associations between body satisfaction and weight-related health-promoting and health-compromising behaviors five years later among adolescents. METHODS: Project EAT-II followed an ethnically and socioeconomically diverse sample of 2516 adolescents from 1999 (Time 1) to 2004 (Time 2). Associations between body satisfaction at Time 1 and health behaviors at Time 2 were examined, adjusting for sociodemographic characteristics and Time 1 health behaviors, with and without adjustment for body mass index (BMI). RESULTS: In females, lower body satisfaction predicted higher levels of dieting, unhealthy and very unhealthy weight control behaviors and binge eating, and lower levels of physical activity and fruit and vegetable intake. After adjusting for BMI, associations between body satisfaction and dieting, very unhealthy weight control behaviors, and physical activity remained statistically significant. In males, lower body satisfaction predicted higher levels of dieting, healthy, unhealthy, and very unhealthy weight control behaviors, binge eating, and smoking, and lower levels of physical activity. After adjusting for BMI, associations between body satisfaction and dieting, unhealthy weight control behavior, and binge eating remained statistically significant. CONCLUSIONS: The study findings indicate that, in general, lower body satisfaction does not serve as a motivator for engaging in healthy weight management behaviors, but rather predicts the use of behaviors that may place adolescents at risk for weight gain and poorer overall health. Interventions with adolescents should strive to enhance body satisfaction and avoid messages likely to lead to decreases in body satisfaction.

Adolescent↗

PubMed2006

Self-weighing in adolescents: helpful or harmful? Longitudinal associations with body weight changes and disordered eating.

PURPOSE: This study addresses the question: Is frequent self-weighing related to changes in body weight and disordered eating behaviors over a 5-year period among adolescent females and males? METHODS: Project EAT is a 5-year population-based longitudinal study. Participants completed surveys exploring factors associated with eating and weight concerns. Participants included 2516 adolescents who were transitioning from early to middle adolescence (younger cohort) and from middle to late adolescence (older cohort). RESULTS: In the older cohort of females and in both cohorts of males, frequent self-weighing at Time 1 was not associated with weight changes at Time 2 (5 years later), after adjusting for Time 1 weight status and sociodemographic characteristics. In the younger cohort of females, Time 1 frequent self-weighing predicted weight increases at Time 2. In both cohorts of females, but not in males, Time 1 frequent self-weighing predicted higher prevalences of Time 2 disordered eating behaviors, including unhealthy weight control behaviors and binge eating, after adjusting for Time 1 behavioral outcomes, weight status, and sociodemographic characteristics. CONCLUSIONS: Frequent self-weighing was not associated with weight change, with the exception of predicting weight increases in younger females. In females, but not males, self-weighing predicted a higher frequency of binge eating and unhealthy weight control behaviors. Although further research is needed to explore the potential merits and problems associated with regular self-weighing, the findings suggest that population-based obesity prevention strategies targeting adolescents should avoid messages likely to lead to frequent self-weighing.

Adolescent↗

PubMed2006

Body dissatisfaction prospectively predicts depressive mood and low self-esteem in adolescent girls and boys.

This research examined whether body dissatisfaction prospectively predicted depressive mood and low self-esteem in adolescent girls and boys 5 years later. Participants were early-adolescent girls (n = 440, Time 1 M age = 12.7 years) and boys (n = 366, Time 1 M age = 12.8 years) and midadolescent girls (n = 946, Time 1 M age = 15.8 years) and boys (n = 764, Time 1 M age = 15.9 years). After controlling for Time 1 of the relevant dependent variable, ethnicity, socioeconomic status, and body mass index, Time 1 body dissatisfaction was a unique predictor of Time 2 depressive mood and low self-esteem in early-adolescent girls (depressive mood: F = 4.80, p < .05; self-esteem: F = 9.64, p < .01) and midadolescent boys (depressive mood: F = 12.27, p < .001; self-esteem: F = 9.38, p < .01) but not in early-adolescent boys or midadolescent girls. These findings are consistent with the hypothesis that body dissatisfaction is a risk factor for depressive mood and low self-esteem in both girls and boys but in different phases of adolescence.

Adolescent↗

PubMed2006

School-level intraclass correlation for physical activity in sixth grade girls.

PURPOSE: The Trial for Activity in Adolescent Girls (TAAG) is a group-randomized trial (GRT) to reduce the usual decline in moderate to vigorous physical activity (MVPA) among middle school girls. We report the school-level intraclass correlation (ICC) for MVPA from the TAAG baseline survey of sixth grade girls and describe the relationship between the schedule of data collection and the ICC. METHODS: Each of six sites recruited six schools and randomly selected 60 sixth grade girls from each school; 74.2% participated. Girls were grouped in waves defined by the date measurements began and asked to wear an Actigraph accelerometer for 6 d. Occasional missing data were replaced by imputation, and counts above 1500 per 30 s were treated as MVPA, converted into metabolic equivalents (METs), and summed over 6 a.m.-midnight to provide MET-minutes per 18-h day. Mixed-model regression was used to estimate ICC. RESULTS: The school-level ICC were higher when estimated from a single wave compared with three waves (e.g., 0.057 vs 0.022) and across weekdays compared with weekend days (e.g., 0.024 vs 0.012). Power in a new trial would be greater with some schedules (e.g., 88% given three waves and 6 d) than with others (e.g., 23% given one wave and Tuesday only). CONCLUSIONS: The schedule of data collection can have a dramatic effect on the ICC for MVPA. In turn, this can have a dramatic effect on the standard error for an intervention effect and on power. Investigators will need to consider the expected magnitude of the ICC and the validity of the MVPA estimates associated with their data collection schedule in planning a new study.

Child↗

PubMed2006

Weight teasing and disordered eating behaviors in adolescents: longitudinal findings from Project EAT (Eating Among Teens).

OBJECTIVE: To assess whether weight-related teasing predicts the development of binge eating, unhealthy weight control behaviors, and frequent dieting among male and female adolescents. METHODS: A prospective study was conducted with an ethnically and socioeconomically diverse sample of 2516 adolescents who completed surveys at both time 1 (1998-1999) and time 2 (2003-2004) of the Project EAT (Eating Among Teens) study. RESULTS: In 1998-1999, approximately one fourth of participants reported being teased about their weight at least a few times a year. After adjustment for age, race/ethnicity, socioeconomic status (SES), and BMI, boys who were teased about their weight were more likely than their peers to initiate binge eating with loss of control and unhealthy weight control behaviors 5 years later. The predicted prevalence for incident binge eating behaviors with loss of control among boys who were teased was 4.1% as compared with 1.4% for those who were not teased, after adjustment for age, race/ethnicity, SES, and BMI. For unhealthy weight control behaviors at time 2, the predicted prevalence was 27.5% among boys who were teased and 19.3% for boys who were not teased, after adjustment for age, race/ethnicity, SES, and BMI. Girls who were teased were more likely than their peers to become frequent dieters. The predicted prevalence for incident frequent dieting among girls who were teased was 18.2% as compared with 11.0% for those who were not teased, after adjustment for age, race/ethnicity, SES, and BMI. CONCLUSIONS: Weight teasing in adolescence predicts disordered eating behaviors at 5-year follow-up. The patterns of these associations differ by gender. Reducing teasing through educational interventions and policies may reduce the level of disordered eating behaviors among youths.

Adolescent↗

PubMed2006

Longitudinal and secular trends in physical activity and sedentary behavior during adolescence.

OBJECTIVE: There is little epidemiologic research on longitudinal and secular trends in weight-related health behaviors throughout the stages of adolescence. In particular, few data are available to assess secular trends in various sedentary behaviors. The objective of this research was to investigate longitudinal and secular trends in physical activity and sedentary behavior in a large, diverse cohort of adolescents. METHODS: Project EAT-II is a 5-year longitudinal study (N = 2516) that includes 2 cohorts that allow for the observation of longitudinal changes from early to midadolescence (junior high to high school; n = 806; mean baseline age: 12.8 +/- 0.8 years) and mid- to late adolescence (high school to post-high school; n = 1710; mean baseline age: 15.8 +/- 0.8 years). EAT-II also examined secular trends in health behavior from 1999 to 2004 in midadolescence. The main outcome measures of the mixed-model regression analyses used in this research were self-reported weekly hours of moderate to vigorous physical activity, television/video viewing, and leisure-time computer use. RESULTS: Our findings indicate substantial longitudinal changes in moderate to vigorous physical activity, particularly among girls (decreasing 5.9-4.9 hours/week from early to midadolescence and 5.1-3.5 hours/week from mid- to late adolescence), and leisure-time computer use, particularly among boys (increasing 11.4-15.2 hours/week from early to midadolescence and 10.4-14.2 hours/week from mid- to late adolescence). Secular trends further indicate dramatic increases in midadolescent computer use from 1999 to 2004; girls increased from 8.8 to 11.1 hours/week, and boys increased from 10.4 to 15.2 hours/week. CONCLUSIONS: These adolescents experienced unfavorable shifts in activity patterns, such as longitudinal decreases in moderate to vigorous physical activity, coupled with longitudinal and secular increases in leisure-time computer use. Developing effective health promotion strategies that address a wide array of changing behavioral patterns will be important in promoting long-term health and active lifestyles among adolescents and young adults.

Adolescent↗

PubMed2005

Small-sample performance of the robust score test and its modifications in generalized estimating equations.

The sandwich variance estimator of generalized estimating equations (GEE) may not perform well when the number of independent clusters is small. This could jeopardize the validity of the robust Wald test by causing inflated type I error and lower coverage probability of the corresponding confidence interval than the nominal level. Here, we investigate the small-sample performance of the robust score test for correlated data and propose several modifications to improve the performance. In a simulation study, we compare the robust score test to the robust Wald test for correlated Bernoulli and Poisson data, respectively. It is confirmed that the robust Wald test is too liberal whereas the robust score test is too conservative for small samples. To explain this puzzling operating difference between the two tests, we consider their applications to two special cases, one-sample and two-sample comparisons, thus motivating some modifications to the robust score test. A modification based on a simple adjustment to the usual robust score statistic by a factor of J/(J - 1) (where J is the number of clusters) reduces the conservativeness of the generalized score test. Simulation studies mimicking group-randomized clinical trials with binary and count responses indicated that it may improve the small-sample performance over that of the generalized score and Wald tests with test size closer to the nominal level. Finally, we demonstrate the utility of our proposal by applying it to a group-randomized clinical trial, trying alternative cafeteria options in schools (TACOS).

Adolescent↗

PubMed2005

School lunch and snacking patterns among high school students: associations with school food environment and policies.

OBJECTIVES: This study examined associations between high school students' lunch patterns and vending machine purchases and the school food environment and policies. METHODS: A randomly selected sample of 1088 high school students from 20 schools completed surveys about their lunch practices and vending machine purchases. School food policies were assessed by principal and food director surveys. The number of vending machines and their hours of operation were assessed by trained research staff. RESULTS: Students at schools with open campus policies during lunchtime were significantly more likely to eat lunch at a fast food restaurant than students at schools with closed campus policies (0.7 days/week vs. 0.2 days/week, p < .001). Student snack food purchases at school were significantly associated with the number of snack machines at schools (p < .001) and policies about the types of food that can be sold. In schools with policies, students reported making snack food purchases an average of 0.5 +/- 1.1 days/week as compared to an average of 0.9 +/- 1.3 days/week in schools without policies (p < .001). In schools in which soft drink machines were turned off during lunch time, students purchased soft drinks from vending machines 1.4 +/- 1.6 days/week as compared to 1.9 +/- 1.8 days/week in schools in which soft drink machines were turned on during lunch (p = .040). CONCLUSION: School food policies that decrease access to foods high in fats and sugars are associated with less frequent purchase of these items in school among high school students. Schools should examine their food-related policies and decrease access to foods that are low in nutrients and high in fats and sugars.

Journal Article↗

PubMed2005

Eliminating diagnostic drift in the validation of acute in-hospital myocardial infarction--implication for documenting trends across 25 years: the Minnesota Heart Survey.

Long-term trends in epidemiologic studies of acute myocardial infarction (AMI) require application of a consistent diagnostic algorithm. Typically an algorithm includes chest pain, cardiac enzymes, electrocardiographic findings, and autopsy results. The Minnesota Heart Survey (MHS) has determined trends for incident AMI and for in-hospital and long-term outcomes over a 25-year period (1970-1995). However, dramatic changes have occurred that seriously challenge the ability of the MHS and other epidemiologic studies to use a consistent diagnostic algorithm. These include newer and more sensitive cardiac biomarkers, introduction of diagnosis-related groups, and change in International Classification of Diseases coding. In the MHS, the electrocardiogram is the only diagnostic element consistently available and consistently classified over this 25-year period. The authors identified eight dichotomous Minnesota Code criteria that provided a consistent diagnostic method from 1970 to 1995 as documented by extensive cross-validation. These criteria were combined into a logistic score and used to define incident, recurrent, and attack AMI rates over this 25-year period. For both men and women, AMI rates determined by electrocardiogram are parallel to rates based on the International Classification of Diseases and parallel over adjacent survey periods to the standard MHS algorithm. The electrocardiogram classified by Minnesota Code provides the only consistent long-term diagnostic tool for AMI trends over this 25-year period.

Adult↗

PubMed2005

Design of the Trial of Activity in Adolescent Girls (TAAG).

The primary aim of the Trial of Activity in Adolescent Girls (TAAG) is to test an intervention to reduce by half the age-related decline in moderate to vigorous physical activity (MVPA) in middle school girls. The intervention will be evaluated using a group-randomized trial involving 36 middle schools. The primary endpoint is the mean difference in intensity-weighted minutes (i.e., MET-minutes) of MVPA between intervention and comparison schools assessed using accelerometry. The TAAG study design calls for two cross-sectional samples, one drawn from 6th graders at the beginning of the study and the second drawn from 8th graders at the end of the study following the 2-year implementation of the intervention. An important strength of this design over a cohort design is the consistency with the goals of TAAG, which focus on environmental-level rather than individual-level interventions to produce change. The study design specifies a recruitment rate of 80% and a smaller sample of girls at baseline (n=48 per school) than at follow-up (n=96 per school). A two-stage model will be used to test the primary hypothesis. In the first stage, MET-weighted minutes of MVPA will be regressed on school, time (baseline or follow-up), their interaction, ethnicity and week of data collection. The second stage analysis will be conducted on the 72 adjusted means from the first stage. In the main-effects model, we will regress the follow-up school mean MET-weighted minutes of MVPA on study condition, adjusting for the baseline school mean. The TAAG study addresses an important health behavior, and also advances the field of group-randomized trials through the use of a study design and analysis plan tailored to serve the main study hypothesis.

Adolescent↗

PubMed2005

Safety and efficacy of weight training in recent breast cancer survivors to alter body composition, insulin, and insulin-like growth factor axis proteins.

BACKGROUND: This randomized controlled trial assessed the safety and effects of twice-weekly weight training among recent breast cancer survivors. Outcomes included body size and biomarkers hypothesized to link exercise and breast cancer risk. METHODS: A convenience sample of 85 recent survivors was randomized into immediate and delayed treatment groups. The immediate group trained from months 0 to 12; the delayed treatment group served as a no exercise parallel comparison group from months 0 to 6 and trained from months 7 to 12. Measures at baseline, 6 and 12 months included body weight, height, body fat, lean mass, body fat %, and waist circumference, as well as fasting glucose, insulin, insulin resistance, insulin-like growth factor-I (IGF-I), IGF-II, and IGF-binding protein-1, IGFBP-2, and IGFBP-3. Injury reporting was standardized. RESULTS: The intervention resulted in significant increases in lean mass (0.88 versus 0.02 kg, P < 0.01), as well as significant decreases in body fat % (-1.15% versus 0.23%, P = 0.03) and IGF-II (-6.23 versus 28.28 ng/mL, P = 0.02) comparing immediate with delayed treatment from baseline to 6 months. Within-person changes experienced by delayed treatment group participants during training versus no training were similar. Only one participant experienced a study related injury that prevented continued participation. CONCLUSION: Twice-weekly weight training is a safe exercise program for recent breast cancer survivors that may result in increased muscle mass, as well as decreased body fat % and IGF-II. The implications of these results on cancer recurrence or survival may become more evident with longer exercise intervention trials among breast cancer survivors.

Body Composition↗

PubMed2005

Increasing the degrees of freedom in existing group randomized trials: the df* approach.

This study describes a method for incorporating external estimates of intraclass correlation to improve the precision for the analysis of an existing group-randomized trial. The authors use a random-effects meta-analytic approach to pool the information across studies, which takes into account any interstudy heterogeneity that may exist. This approach can be used in several different situations to estimate the degrees of freedom available for an adjusted test of the intervention effect in a study where the challenges of group-randomized trials were not fully considered when the study was planned. The authors discuss the limitations of this approach and the circumstances in which it is likely to be helpful.

Humans↗