Assessing dimensionality in dichotomous items when many subjects have all-zero responses: an example from psychiatry and a solution using mixture models

Common methods for determining the number of latent dimensions underlying an item set include eigenvalue analysis and examination of fit statistics for factor analysis models with varying number of factors. Given a set of dichotomous items, the authors demonstrate that these empirical assessments of dimensionality often incorrectly estimate the number of dimensions when there is a preponderance of individuals in the sample with all-zeros as their responses, for example, not endorsing any symptoms on a health battery. Simulated data experiments are conducted to demonstrate when each of several common diagnostics of dimensionality can be expected to under- or over-estimate the true dimensionality of the underlying latent variable. An example is shown from psychiatry assessing the dimensionality of a social anxiety disorder battery where 1, 2, 3, or more factors are identified, depending on the method of dimensionality assessment. An all-zero inflated exploratory factor analysis model (AZ-EFA) is introduced for assessing the dimensionality of the underlying subgroup corresponding to those possessing the measurable trait. The AZ-EFA approach is demonstrated using simulation experiments and an example measuring social anxiety disorder from a large nationally representative survey. Implications of the findings are discussed, in particular, regarding the potential for different findings in community versus patient populations

Gender differences in treatment adherence among youth with cystic fibrosis: Development of a new questionnaire

AbstractBackgroundSome prior studies have reported that girls with cystic fibrosis (CF) experience higher morbidity and mortality compared to boys. In this study, the authors compared boys' and girls' perceptions of disease-related strains and resources associated with living with CF, and the relationship of these factors to CF treatment feelings and behaviors.MethodsAll 10–21 year olds with CF at the Minnesota Cystic Fibrosis Center were invited by mail to complete a new self-report survey (Living with CF Questionnaire — LCFQ). Of these 177 youth, 58% (49 boys and 54 girls) returned surveys.ResultsExploratory and confirmatory factor analyses revealed nine factors in the LCFQ. Partial support was found for hypothesized gender differences in these factors. Compared to boys, girls reported significantly more illness-related strains and worries, including emotional strains, greater treatment discouragement, lower self-esteem, and lower adherence to some aspects of the CF treatment regimen (coughing, eating high-fat foods, taking meds/pills).ConclusionsLiving with CF appears to have a greater emotional impact on adolescent girls compared to boys. These gender differences may contribute to the poorer pulmonary function observed among girls with cystic fibrosis during the adolescent years

Predictors of initiation and persistence of unhealthy weight control behaviours in adolescents

<p>Abstract</p> <p>Background</p> <p>Unhealthy weight control behaviours (UWCB) among adolescents have significant health and weight consequences. The current longitudinal study aimed to identify personal and socio-environmental predictors of initiation or persistence of adolescent UWCB, in order to inform development of programs aimed at both preventing and stopping UWCB.</p> <p>Methods</p> <p>A diverse sample included 1106 boys and 1362 girls from 31 middle schools and high schools in the United States who were enrolled in Project EAT (Eating Among Teens). Project EAT explored personal, behavioural, and socio-environmental factors associated with dietary intake and body weight in adolescence. Participants completed questionnaires to assess demographics, UWCB (including several methods of food restriction, purging by vomiting or medications, smoking to control weight, or food substitutions) and personal and socio-environmental variables at two time points, five years apart, between 1998 and 2004. Logistic regression models examined personal and socio-environmental predictors of initiation and persistence of UWCB among Project EAT participants.</p> <p>Results</p> <p>Results indicate that 15.5% of boys and 19.7% of girls initiated UWCB by Time 2, and 15.9% of boys and 43.3% of girls persisted with these behaviours from Time 1 to Time 2. After controlling for race/ethnicity and weight status changes between assessments, logistic regression models indicated that similar factors and patterns of factors were associated significantly with initiation and persistence of UWCB. For both boys and girls, personal factors had more predictive value than socio-environmental factors (Initiation models: for boys: <it>R</it>²= 0.35 for personal vs. 0.27 for socio-environmental factors; for girls, <it>R</it>²= 0.46 for personal vs. 0.26 for socio-environmental factors. Persistence models: for boys: <it>R</it>²= 0.53 for personal vs. 0.33 for socio-environmental factors; for girls, <it>R</it>²= 0.41 for personal vs. 0.19 for socio-environmental factors). The weight concerns model was the strongest predictor among all individual models [Initiation odds ratios (ORs) and 95% confidence interval (CI): 4.84 (3.32-7.01) for boys and 5.09 (3.55-7.30) for girls; persistence OR (CI): 4.55 (2.86-7.14) for boys and 3.45 (2.50-4.76) for girls].</p> <p>Conclusion</p> <p>In general, predictors of initiation and persistence of UWCB were similar, suggesting that universal and selective prevention programs can target similar risk factors.</p

Trends in Marijuana Use Among Pregnant and Nonpregnant Reproductive-Aged Women, 2002-2014

Between 2001 and 2013, marijuana use among US adults more than doubled, many states legalized marijuana use, and attitudes toward marijuana became more permissive. In aggregated 2007-2012 data, 3.9% of pregnant women and 7.6% of nonpregnant reproductive-aged women reported past-month marijuana use. Although the evidence is mixed, human and animal studies suggest that prenatal marijuana exposure may be associated with poor offspring outcomes (eg, low birth weight, impaired neurodevelopment). The American College of Obstetricians and Gynecologists recommends that pregnant women and women contemplating pregnancy be screened for and discouraged from using marijuana and other substances. Whether marijuana use has changed over time among pregnant and nonpregnant reproductive-aged women is unknown

How does state marijuana policy affect US youth? Medical marijuana laws, marijuana use and perceived harmfulness: 1991–2014

AimsTo test, among US students: (1) whether perceived harmfulness of marijuana has changed over time, (2) whether perceived harmfulness of marijuana changed post‐passage of state medical marijuana laws (MML) compared with pre‐passage; and (3) whether perceived harmfulness of marijuana statistically mediates and/or modifies the relation between MML and marijuana use as a function of grade level.DesignCross‐sectional nationally representative surveys of US students, conducted annually, 1991–2014, in the Monitoring the Future study.SettingSurveys conducted in schools in all coterminous states; 21 states passed MML between 1996 and 2014.ParticipantsThe sample included 1 134 734 adolescents in 8th, 10th and 12th grades.MeasurementsState passage of MML; perceived harmfulness of marijuana use (perceiving great or moderate risk to health from smoking marijuana occasionally versus slight or no risk); and marijuana use (prior 30 days). Data were analyzed using time‐varying multi‐level regression modeling.FindingsThe perceived harmfulness of marijuana has decreased significantly since 1991 (from an estimated 84.0% in 1991 to 53.8% in 2014, P < 0.01) and, across time, perceived harmfulness was lower in states that passed MML [odds ratio (OR) = 0.86, 95% confidence interval (CI) = 0.75–0.97]. In states with MML, perceived harmfulness of marijuana increased among 8th graders after MML passage (OR = 1.21, 95% CI = 1.08–1.36), while marijuana use decreased (OR = 0.81, 95% CI = 0.72–0.92). Results were null for other grades, and for all grades combined. Increases in perceived harmfulness among 8th graders after MML passage was associated with ~33% of the decrease in use. When adolescents were stratified by perceived harmfulness, use in 8th graders decreased to a greater extent among those who perceived marijuana as harmful.ConclusionsWhile perceived harmfulness of marijuana use appears to be decreasing nationally among adolescents in the United States, the passage of medical marijuana laws (MML) is associated with increases in perceived harmfulness among young adolescents and marijuana use has decreased among those who perceive marijuana to be harmful after passage of MML.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134418/1/add13523_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134418/2/add13523.pd

Prevalence of marijuana use does not differentially increase among youth after states pass medical marijuana laws: Commentary on Stolzenberg et al. (2015) and reanalysis of US National Survey on Drug Use in Households data 2002–2011

There is considerable interest in the effects of medical marijuana laws (MML) on marijuana use in the USA, particularly among youth. The article by Stolzenberg et al. (2015) “The effect of medical cannabis laws on juvenile cannabis use” concludes that “implementation of medical cannabis laws increase juvenile cannabis use”. This result is opposite to the findings of other studies that analysed the same US National Survey on Drug Use in Households data as well as opposite to studies analysing other national data which show no increase or even a decrease in youth marijuana use after the passage of MML. We provide a replication of the Stolzenberg et al. results and demonstrate how the comparison they are making is actually driven by differences between states with and without MML rather than being driven by pre and post-MML changes within states. We show that Stolzenberg et al. do not properly control for the fact that states that pass MML during 2002–2011 tend to already have higher past-month marijuana use before passing the MML in the first place. We further show that when within-state changes are properly considered and pre-MML prevalence is properly controlled, there is no evidence of a differential increase in past-month marijuana use in youth that can be attributed to state MML

Physical Activity and Screen Time in Adolescents and Their Nominated Friends

Background: The social transmission of obesity has been reported in adolescent social networks. However, the behavioral antecedents to obesity (physical activity [PA], screen time, and diet) are the factors that would actually be transmitted through these networks. To date, little is known about the social influences affecting an individual adolescent’s PA and screen time behaviors. Purpose: To determine the associations between an adolescent’s PA and screen time and his/her nominated friends’ PA and screen time. Methods: Data were obtained from EAT 2010 (Eating and Activity among Teens), a large cross-sectional study (n=2,126) conducted in 20 middle schools and high schools in Minneapolis/St. Paul, Minnesota, USA during the 2009-2010 academic year. Each participant (Ego) nominated up to six friends (Alters) from a school roster and data from those friends was also obtained as part of the school-based data collection procedures. PA and screen time were assessed with previously used and validated questionnaires. Generalized estimating equation models, stratified by gender, were used to assess associations between adolescents’ PA and screen time and their friends’ PA and screen time. Results: Females’ PA was associated with their male and female friends’ PA, including their female best friends (all p\u3c0.05). Males’ PA was associated with their female friends’ PA (p\u3c0.03). Females’ screen time was associated with their male and female friends’ screen time (p\u3c0.03), but not with their best friends. Males’ screen time was only associated with their female friends’ screen time (p=0.04). Conclusions: The associations between individual and friend PA and screen time, especially in females, indicate a need to consider these social relationships when investigating weight-related behaviors in adolescents. Longitudinal data using validated measures of PA and screen time, and analyzed using sophisticated modeling techniques are needed to better understand social influences on adolescent weight-related behaviors and inform future intervention efforts

Racial/ethnic differences in use of alcohol, tobacco, and marijuana: Is there a cross-over from adolescence to adulthood?

Black adolescents in the US are less likely to use alcohol, marijuana, and tobacco compared with non-Hispanic Whites, but little is known about the consistency of these racial/ethnic differences in substance use across the lifecourse. Understanding lifecourse patterning of substance use is critical to inform prevention and intervention efforts. Data were drawn from four waves of the National Longitudinal Study of Adolescent Health (Add Health; Wave 1 (mean age = 16): N = 14,101; Wave 4 (mean age = 29): N = 11,365). Outcomes included alcohol (including at-risk drinking, defined as 5+/4+ drinks per drinking occasion or 14+/7+ drinks per week on average for men and women, respectively), cigarette, and marijuana use in 30-day/past-year. Random effects models stratified by gender tested differences-in-differences for wave by race interactions, controlling for age, parents' highest education/income, public assistance, and urbanicity. Results indicate that for alcohol, Whites were more likely to use alcohol and engage in at-risk alcohol use at all waves. By mean age 29.9, for example, White men were 2.1 times as likely to engage in at-risk alcohol use (95% C.I. 1.48–2.94). For cigarettes, Whites were more likely to use cigarettes and smoked more at Waves 1 through 3; there were no differences by Wave 4 for men and a diminished difference for women, and difference-in-difference models indicated evidence of convergence. For marijuana, there were no racial/ethnic differences in use for men at any wave. For women, by Wave 4 there was convergence in marijuana use and a cross-over in frequency of use among users, with Black women using more than White women. In summary, no convergence or cross-over for racial/ethnic differences through early adulthood in alcohol use; convergence for cigarette as well as marijuana use. Lifecourse patterns of health disparities secondary to heavy substance use by race and ethnicity may be, at least in part, due to age-related variation in cigarette and marijuana use

Recruiting and retaining service agencies and public health providers in longitudinal studies: Implications for community-engaged implementation research

This article addresses a lack of attention in the implementation science literature regarding how to overcome recruitment and retention challenges in longitudinal studies involving large samples of service agencies and health service providers (“providers”). Herein, we provide a case-illustration of procedures that improved recruitment and retention in a longitudinal, mixed-method study—Project Interprofessional Collaboration Implementation—funded by the US National Institute of Mental Health. Project Interprofessional Collaboration Implementation included counselors, program workers, educators, and supervisors. We present a research-engagement model to overcome barriers that included developing a low-burden study, social gatherings to engage stakeholders, protocols to recruit agencies and providers, comprehensive record-keeping, research procedures as incentives to participation, a plan to retain hard-to-reach participants, and strategies for modifying incentives over time. Using our model, we retained 36 agencies over the life of the project. Between baseline (N = 379) and 12-month follow-up (N = 285), we retained 75% of the sample and between the 12- (N = 285) and 24-month follow-ups (N = 256), we retained 90%. For qualitative interviews (between baseline and 12-month follow-up and between 12- and 24-month follow-ups), we retained 100% of the sample (N = 20). We provide a summary of frequency of contacts required to initiate data collection and time required for data collection. The model responded to environmental changes in policy and priorities that would not have been achievable without the expertise of community partners. To recruit and retain large samples longitudinally, researchers must strategically engage community partners. The strategies imbedded in our model can be performed with moderate levels of effort and human resources. Creating opportunities for research partners to participate in all phases of the research cycle is recommended, which can help build research capacity for future research