Katherine E. Masyn

Discrete-Time Survival Mixture Analysis.

This article proposes a general latent variable approach to discrete-time survival analysis of nonrepeatable events such as onset of drug use. It is shown how the survival analysis can be formulated as a generalized latent class analysis of event history indicators. The latent class analysis can use covariates and can be combined with the joint modeling of other outcomes such as repeated measures for a related process. It is shown that conventional discrete-time survival analysis corresponds to a single-class latent class analysis. Multiple-class extensions are proposed, including the special cases of a class of long-term survivors and classes defined by outcomes related to survival. The estimation uses a general latent variable framework, including both categorical and continuous latent variables and incorporated in the Mplus program. Estimation is carried out using maximum likelihood via the EM algorithm. Two examples serve as illustrations. The first example concerns recidivism after incarceration in a randomized field experiment. The second example concerns school removal related to the development of aggressive behavior in the classroom.

A comparison of girls' and boys' aggressive-disruptive behavior trajectories across elementary school: Prediction to young adult antisocial outcomes.

Multiple group analysis and general growth mixture modeling was used to determine whether aggressive- disruptive behavior trajectories during elementary school, and their association with young adulthood antisocial outcomes, vary by gender. Participants were assessed longitudinally beginning at age 6 as part of an evaluation of 2 school-based preventive programs. Two analogous trajectories were found for girls and boys: chronic high aggression- disruption (CHAD) and stable low aggression- disruption (LAD). A 3rd class of low moderate aggression- disruption (LMAD) for girls and increasing aggression- disruption (IAD) for boys also was found. Girls and boys in analogous CHAD classes did not differ in trajectory level and course, but girls in the CHAD and LAD classes had lower rates of antisocial outcomes than boys. Girls with the LMAD trajectory differed from boys with the IAD trajectory.

Molecular and imaging correlates of the fragile X-associated tremor/ataxia syndrome.

Objectives: To assess changes in regional brain volumes associated with the fragile X–associated tremor/ataxia syndrome (FXTAS) and the molecular correlates of these changes. Methods: We administered molecular, MRI, and neurocognitive tests to 36 male premutation carriers (ages 51 to 79), 25 affected and 11 unaffected with FXTAS, and to 21 control subjects of similar age and education. Results: We found differences among the three groups in whole brain, cerebrum, cerebellum, ventricular volume, and whole-brain white matter hyperintensity, with the affected group showing significantly more pathology than the control and unaffected groups. Brainstem volume was significantly smaller in the unaffected group vs controls but did not differ from the affected group. Within the premutation sample, CGG repeat length correlated with reductions in IQ and cerebellar volume and increased ventricular volume and whole-brain white matter hyperintensity. Conclusions: The current findings, coupled with recent evidence linking the degree of neuropathology (numbers of intranuclear inclusions) to the size of the premutation allele, provide evidence that the neurodegenerative phenotype in the fragile X–associated tremor/ataxia syndrome is a consequence of the CGG repeat expansion.

General Growth Mixture Analysis with Antecedents and Consequences of Change

Many studies of youth, adolescents, and adults related to delinquent, antisocial, and criminal offending, have utilized a language of trajectory typologies to describe individual differences in the behavioral course manifest in their longitudinal data. The two most common statistical methods currently in use are the semiparametric group-based modeling, also known as latent class growth analysis and general growth mixture analysis, with the latter method being the focus of this chapter. In concert with the growing popularity of these data-driven, group-based methods for studying developmental and life-course behavior trajectories have come active and spirited ontological discussions about the nature of the emergent trajectory groups resulting from the analyses. In this chapter, we presuppose that there are analytic, empirical, and substantive advantages inherent in using discrete components to (partially) describe population heterogeneity in longitudinal processes. Conceptually as well as empirically, we will discuss the use of auxiliary information in terms of antecedents and consequences of trajectory group membership. The inclusion of auxiliary information in growth mixture analysis is a necessary step in understanding as well as evaluating the fidelity and utility of the resultant trajectory profiles from a given study, regardless of one’s beliefs about the veracity of the method itself.

Assessing differential effects: applying regression mixture models to identify variations in the influence of family resources on academic achievement.

Developmental scientists frequently seek to understand effects of environmental contexts on development. Traditional analytic strategies assume similar environmental effects for all children, sometimes exploring possible moderating influences or exceptions (e.g., outliers) as a secondary step. These strategies are poorly matched to ecological models of human development that posit complex individual by environment interactions. An alternative conceptual framework is proposed that tests the hypothesis that the environment has differential (nonuniform) effects on children. A demonstration of the utility of this framework is provided by examining the effects of family resources on childrens academic outcomes in a multisite study (N = 6,305). Three distinctive groups of children were identified, including 1 group particularly resilient to influence of low levels of family resources. Predictors of group differences including parenting and child demographics are tested, the replicability of the results are examined, and findings are contrasted with those obtained with traditional regression interaction effects. This approach is proposed as a partial solution to advance theories of the environment, social ecological systems research, and behavioral genetics to create well-tailored environments for children.

Methods for Synthesizing Findings on Moderation Effects Across Multiple Randomized Trials

This paper presents new methods for synthesizing results from subgroup and moderation analyses across different randomized trials. We demonstrate that such a synthesis generally results in additional power to detect significant moderation findings above what one would find in a single trial. Three general methods for conducting synthesis analyses are discussed, with two methods, integrative data analysis and parallel analyses, sharing a large advantage over traditional methods available in meta-analysis. We present a broad class of analytic models to examine moderation effects across trials that can be used to assess their overall effect and explain sources of heterogeneity, and present ways to disentangle differences across trials due to individual differences, contextual level differences, intervention, and trial design.

Development of Mastery during Adolescence: The Role of Family Problem-solving

A sense of mastery is an important component of psychological health and well-being across the life-span; however, relatively little is known about the development of mastery during childhood and adolescence. Utilizing prospective, longitudinal data from 444 adolescent sibling pairs and their parents, our conceptual model proposes that family socioeconomic status (SES) in the form of parental education promotes effective family problem-solving, which, in turn, fosters adolescent mastery. Results show: (1) a significant increase in mastery for younger and older siblings, (2) parental education promoted effective problem-solving between parents and adolescents and between siblings but not between the parents themselves, and (3) all forms of effective family problem-solving predicted greater adolescent mastery. Parental education had a direct effect on adolescent mastery as well as the hypothesized indirect effect through problem-solving effectiveness, suggesting both a social structural and social process influence on the development of mastery during adolescence.

Drinking trajectories following an initial lapse.

Relapse following alcohol treatment is a major problem for individuals who are alcohol dependent, yet little is known about the course of drinking after the initial lapse. In the current study, discrete-time survival analysis and latent growth mixture modeling were used to evaluate the time to first lapse and the trajectories of postlapse drinking in a sample of 563 individuals who received community alcohol treatment. Results showed a decreasing risk of lapsing over time. After the initial lapse, 3 trajectory subgroups provided a parsimonious representation of the heterogeneity in postlapse drinking frequency and quantity, with the majority of individuals reporting light, infrequent drinking. Covariate analyses incorporating demographics, distal risk factors, time to first lapse, and coping behavior as predictors of time to lapse and postlapse drinking trajectories indicated that alcohol dependence and coping behavior were the strongest predictors of lapsing and postlapse drinking behavior.

Co-occurring risk behaviors among White, Black, and Hispanic US high school adolescents with suicide attempts requiring medical attention, 1999-2007: Implications for future prevention initiatives

PurposeTo identify subtypes of adolescent suicide attempters by examining risk profiles related to substance use, violent behavior, and depressive symptoms. To examine the relationship between these subtypes and having had two or more suicide attempts during the past year. To explore race and gender differences across subtypes of suicide attempters.MethodsData were combined from five nationally representative cohorts of the US Youth Risk Behavior Surveillance System (YRBSS) and focused on a subpopulation of youth who reported a suicide attempt requiring medical attention. Latent class analysis was used to identify subtypes of suicide attempters.ResultsAnalysis yielded three classes of youth who attempted suicide, distinguishable by their levels of substance use and violent behaviors: low substance use and violent behaviors, high substance use and violent behaviors, and extreme substance use and violent behaviors. All three classes had a high propensity for endorsing depressive symptoms. The proportion of youth with two or more suicide attempts during the past year increased across subgroup of attempters with higher levels of substance use and violent behaviors. Racial and gender differences were found across subtypes of suicide attempters.ConclusionsPreventing and treating the co-occurrence of substance use and violent behaviors may serve as essential strategies for reducing suicide attempts, especially among male youth. The use of public health strategies for suicide prevention should take into account the different needs of youth at risk for suicide.

Initiation and Persistence of Alcohol Use in United States Black, Hispanic, and White Male and Female Youth

BACKGROUND The relation between early and frequent alcohol use and later difficulties is quite strong. However, the degree that alcohol use persists, which is often a necessary cause for developing alcohol-related problems or an alcohol use disorder, is not well studied, particularly with attention to race and gender. A novel statistical approach, the Multi-facet Longitudinal Model, enables the concurrent study of age of initiation and persistence. METHODS The models were applied to longitudinal data on youth alcohol use from ages 12 through 19, collected in the (U.S.) National Longitudinal Survey of Youth 1997 cohort (N=8984). RESULTS Results confirmed that Black adolescents initiate alcohol use at later ages than do White youth. Further, after initiation, White adolescents were substantially more likely than Black adolescents to continue reporting alcohol use in subsequent years. Hispanic teens showed an intermediate pattern. Gender differences were more ambiguous, with a tendency for boys to be less likely to continue drinking after initiation than were girls. CONCLUSIONS Novel findings from the new analytic models suggest differential implications of early alcohol use by race and gender. Early use of alcohol might be less consequential for males who initiate alcohol use early, Black, and Hispanic youth than for their female and White counterparts.