A latent variable mixed-effects location scale model that also considers between-person differences in the autocorrelation.

In public health research an increasing number of studies is conducted in which intensive longitudinal data is collected in an experience sampling or a daily diary design. Typically, the resulting data is analyzed with a mixed-effects model or mixed-effects location scale model because they allow one to examine a host of interesting longitudinal research questions. Here, we introduce an extension of the mixed-effects location scale model in which measurement error of the observed variables is considered by a latent factor model and in which-in addition to the mean-or location-related effects-the residual variance of the latent factor and the parameters of the autoregressive process of this latent factor can differ between persons. We show how to estimate the parameters of the model with a maximum likelihood approach, whose performance is also compared with a Bayesian approach in a small simulation study. We illustrate the models using a real data example and end with a discussion in which we suggest questions for future research.

Mixed-Methods Study of Disability Self-Management in Mexican Americans With Osteoarthritis.

BACKGROUND: Health disparities in osteoarthritis (OA) outcomes exist both in the occurrence and treatment of functional limitation and disability for Mexican Americans. Although the effect of self-management of chronic illness is well established, studies demonstrate little attention to self-management of function or disability, despite the strong potential effect on both and, consequently, on patients' lives. OBJECTIVE: The purpose of this study pilot was to develop and test key variable relationships for a measure of disability self-management among Mexican Americans. METHODS: In this sequential, two-phased, mixed-methods, biobehavioral pilot study of Mexican American women and men with OA, a culturally tailored measure of disability self-management was created, and initial relationships among key variables were explored. RESULTS: First, a qualitative study of 19 adults of Mexican American descent born in Texas (United States) or Mexico was conducted. The Mexican American Disability Self-Management Scale was created using a descriptive content analysis of interview data. The scale was tested and refined, resulting in 18 items and a descriptive frequency of therapeutic management efforts. Second, correlations between study variables were estimated: Disability and function were negatively correlated. Disability correlated positively with social support and activity effort. Disability correlated negatively with disability self-management, pain, and C-reactive protein. Function was positively correlated with age, pain, and depression. Liver enzymes (alanine transaminase) correlated positively with pain and anxiety. DISCUSSION: This mixed-methods study indicates directions for further testing and interventions for disability outcomes among Mexican Americans.

Bayesian pattern-mixture models for dropout and intermittently missing data in longitudinal data analysis.

Valid inference can be drawn from a random-effects model for repeated measures that are incomplete if whether the data are missing or not, known as missingness, is independent of the missing data. Data that are missing completely at random or missing at random are two data types for which missingness is ignorable. Given ignorable missingness, statistical inference can proceed without addressing the source of the missing data in the model. If the missingness is not ignorable, however, recommendations are to fit multiple models that represent different plausible explanations of the missing data. A popular choice in methods for evaluating nonignorable missingness is a random-effects pattern-mixture model that extends a random-effects model to include one or more between-subjects variables that represent fixed patterns of missing data. Generally straightforward to implement, a fixed pattern-mixture model is one among several options for assessing nonignorable missingness, and when it is used as the sole model to address nonignorable missingness, understanding the impact of missingness is greatly limited. This paper considers alternatives to a fixed pattern-mixture model for nonignorable missingness that are generally straightforward to fit and encourage researchers to give greater attention to the possible impact of nonignorable missingness in longitudinal data analysis. Patterns of both monotonic and non-monotonic (intermittently) missing data are addressed. Empirical longitudinal psychiatric data are used to illustrate the models. A small Monte Carlo data simulation study is presented to help illustrate the utility of such methods.

Alternative covariance structures in mixed-effects models: Addressing intra- and inter-individual heterogeneity.

Mixed-effects models for repeated measures and longitudinal data include random coefficients that are unique to the individual, and thus permit subject-specific growth trajectories, as well as direct study of how the coefficients of a growth function vary as a function of covariates. Although applications of these models often assume homogeneity of the within-subject residual variance that characterizes within-person variation after accounting for systematic change and the variances of the random coefficients of a growth model that quantify individual differences in aspects of change, alternative covariance structures can be considered. These include allowing for serial correlations between the within-subject residuals to account for dependencies in data that remain after fitting a particular growth model or specifying the within-subject residual variance to be a function of covariates or a random subject effect to address between-subject heterogeneity due to unmeasured influences. Further, the variances of the random coefficients can be functions of covariates to relax the assumption that these variances are constant across subjects and to allow for the study of determinants of these sources of variation. In this paper, we consider combinations of these structures that permit flexibility in how mixed-effects models are specified to understand within- and between-subject variation in repeated measures and longitudinal data. Data from three learning studies are analyzed using these different specifications of mixed-effects models.

Longitudinal Effects of Sex, Aging, and Multiple Sclerosis Diagnosis on Function.

BACKGROUND: A gap in research about the trajectories of function among men and women aging with functional limitations because of multiple sclerosis (MS) hinders ability to plan for future needs. OBJECTIVES: Using a biopsychosocial model, we characterize how men and women with MS report changes over time in their function and test how person-level differences in age, diagnosis duration, and sex influence perceived function. METHODS: A longitudinal study with multiple waves of surveys was used to collect data on participant perceptions of function, as well as demographic and contextual variables. Self-reported functional limitation was measured over a decade. The study participants were community residing with physician-diagnosed MS. RESULTS: The people with MS had a diagnosis duration of about 13 years and were around 51 years of age, on average, at the start of the study. They were primarily women and non-Hispanic White. We analyzed the data using mixed-effects models. Subject-specific, functional limitation trajectories were described best with a quadratic growth model. Relative to men, women reported lower functional limitation and greater between-person variation and rates of acceleration in functional limitation scores. DISCUSSION: Results suggest function progressed through two pathways for over a decade, particularly closer to diagnoses. Variability in trajectories between individuals based on sex and years since diagnosis of disease indicates that men and women with MS may experience perceptions of their function with age differently. This has implications for clinician advice to men and women with MS.

The Life-Course Perspectives of Mexican American Men With Mobility Limitation.

The life-history narratives of 10 Mexican American men with mobility limitations, age 55-77 years (mean = 63.8, SD = 5.8), were explored using a qualitatively driven, life-history mixed-methods study to understand perceptions of mobility limitations over the life course. Within that methodological and paradigmatic framework, conceptualizations of alterity and masculinity guided interpretation of data. Through an iterative, thematic analysis, we detail the way the men's lives were influenced by growing familial responsibility with age. Quantitative data were integrated into themes of narrative inheritance, family, and masculinity. It was posited that masculinity with mobility limitations shaped and was shaped by ethnic identity and responsibility. This has implications for understanding the experience of Mexican American men over the life course.

Wine Closure Performance of Three Common Closure Types: Chemical and Sensory Impact on a Sauvignon Blanc Wine.

A Napa Valley Sauvignon blanc wine was bottled with 200 each of a natural cork, a screw cap, and a synthetic cork. As browning is an index for wine oxidation, we assessed the brown color of each bottle with a spectrophotometer over 30 months. A random-effects regression model for longitudinal data on all bottles and closure groups found a browning growth trajectory for each closure group. Changes in the wine's browning behavior at 18 months and 30 months showed that the browning of the wine bottles appeared to slow down later in the storage period, especially for natural corks. The between-bottle variation was the highest for the natural cork. At 30 months, we separated the bottles by the extent of browning and samples were pulled from the high, mid, and low levels of browning levels for each closure. The degree of browning is inversely correlated with free SO2 levels ranging from 5 to 12 mg/L. However, a Quantitative Descriptive Analysis (QDA™) sensory panel could not detect any difference in their aroma and flavor profile between closure types regardless of browning level. Even low levels of free SO2 retain protection against strong oxidation aromas, and visual browning detected by spectrophotometer seemed to precede oxidative aroma and flavor changes of the aging Sauvignon blanc.

Piecewise latent growth models: beyond modeling linear-linear processes.

Piecewise latent growth models (LGMs) for linear-linear processes have been well-documented and studied in recent years. However, in the latent growth modeling literature, advancements to other functional forms as well as to multiple changepoints or knots have been nearly non-existent. This manuscript deals with three extensions. The first is to a piecewise latent growth model incorporating higher-order polynomials. The second is to extend the basic framework to three phases. The last extension is to inherently nonlinear functions. In these extensions, the changepoint(s) is a parameter to be estimated and may be fixed or allowed to vary across subjects as an application warrants. The approaches are developed and two illustrative empirical examples from psychology are used to highlight the methodological nuances. Annotated statistical software is provided to make these elaborations accessible to practitioners and methodologists.

A new look at neurobehavioral development in rhesus monkey neonates (Macaca mulatta).

The Brazelton Neonatal Behavioral Assessment Scale (NBAS) evaluates a newborn infant's autonomic, motor, state, temperament, and social-attentional systems, which can help to identify infants at risk of developmental problems. Given the prevalence of rhesus monkeys being used as an animal model for human development, here we aimed to validate a standardized test battery modeled after the NBAS for use with nonhuman primates called the Infant Behavioral Assessment Scale (IBAS), employing exploratory structural equation modeling using a large sample of rhesus macaque neonates (n = 1,056). Furthermore, we examined the repeated assessments of the common factors within the same infants to describe any changes in performance over time, taking into account two independent variables (infant sex and rearing condition) that can potentially affect developmental outcomes. Results revealed three factors (Orientation, State Control, and Motor Activity) that all increased over the 1st month of life. While infant sex did not have an effect on any factor, nursery-rearing led to higher scores on Orientation but lower scores on State Control and Motor Activity. These results validate the IBAS as a reliable and valuable research tool for use with rhesus macaque infants and suggest that differences in rearing conditions can affect developmental trajectories and potentially pre-expose infants to heightened levels of cognitive and emotional deficiencies.

Two-part mixed-effects location scale models.

Longitudinal time use data afford the opportunity to study within- and between-individual differences, but can present challenges in data analysis. Often the response set includes a large number of zeros representing those who did not engage in the target behavior. Coupled with this is a continuous measure of time use for those who did engage. The latter is strictly positive and skewed to the right if relatively few individuals engage in the behavior to a greater extent. Data analysis is further complicated for repeated measures, because within-individual responses are typically correlated, and some respondents may have missing data. This combination of zeros and positive responses is characteristic of a type of semicontinuous data in which the response is equal to a discrete value and is otherwise continuous. Two-part models have been successfully applied to cross-sectional time use data when the research goals distinguish between a respondent's likelihood to engage in a behavior and the time spent conditional on any time being spent, as these models allow different covariates to relate to each distinct aspect of a behavior. Two-part mixed-effects models extend two-part models for analysis of longitudinal semicontinuous data to simultaneously address longitudinal decisions to engage in a behavior and time spent conditional on any time spent. Heterogeneity between and within individuals can be studied in unique ways. This paper presents applications of these models to daily diary data to study individual differences in time spent relaxing or engaged in leisure activities for an adult sample.

Quality of care to nursing home residents with incontinence.

Quality of care for residents with urinary incontinence (UI) living in nursing facilities was analyzed using data collected from 815 facilities for the Nursing Facility Quality Review in Texas. Overall, of the 1,560 residents, 48.4% (n = 755) experienced UI. The risk of developing UI over a ten-year-period in a nursing facility was 6%. Only 54% of residents with UI had a care plan for their incontinence. For those with a UI plan in their chart, 143 (35%) had a person entered UI plan developed based on that resident's voiding pattern and needs. Further, the creation of a UI plan of care by a RN for a person with UI was associated with a higher perceived level of health after controlling for gender, and age. Finally, the more satisfied the resident was with the response to their calls for help with voiding the more satisfied with the nursing facility.

Exploitation of Interleukin-10 (IL-10) Signaling Pathways: Alternate Roles of Viral and Cellular IL-10 in Rhesus Cytomegalovirus Infection.

There is accumulating evidence that the viral interleukin-10 (vIL-10) ortholog of both human and rhesus cytomegalovirus (HCMV and RhCMV, respectively) suppresses the functionality of cell types that are critical to contain virus dissemination and help shape long-term immunity during the earliest virus-host interactions. In particular, exposure of macrophages, peripheral blood mononuclear cells, monocyte-derived dendritic cells, and plasmacytoid dendritic cells to vIL-10 suppresses multiple effector functions including, notably, those that link innate and adaptive immune responses. Further, vaccination of RhCMV-uninfected rhesus macaques with nonfunctional forms of RhCMV vIL-10 greatly restricted parameters of RhCMV infection following RhCMV challenge of the vaccinees. Vaccinees exhibited significantly reduced shedding of RhCMV in saliva and urine following RhCMV challenge compared to shedding in unvaccinated controls. Based on the evidence that vIL-10 is critical during acute infection, the role of vIL-10 during persistent infection was analyzed in rhesus macaques infected long term with RhCMV to determine whether postinfection vaccination against vIL-10 could change the virus-host balance. RhCMV-seropositive macaques, which shed RhCMV in saliva, were vaccinated with nonfunctional RhCMV vIL-10, and shedding levels of RhCMV in saliva were evaluated. Following robust increases in vIL-10-binding and vIL-10-neutralizing antibodies, shedding levels of RhCMV modestly declined, consistent with the interpretation that vIL-10 may play a functional role during persistent infection. However, a more significant association was observed between the levels of cellular IL-10 secreted in peripheral blood mononuclear cells exposed to RhCMV antigens and shedding of RhCMV in saliva. This result implies that RhCMV persistence is associated with the induction of cellular IL-10 receptor-mediated signaling pathways. IMPORTANCE: Human health is adversely impacted by viruses that establish lifelong infections that are often accompanied with increased morbidity and mortality (e.g., infections with HIV, hepatitis C virus, or human cytomegalovirus). A longstanding but unfulfilled goal has been to develop postinfection vaccine strategies that could "reboot" the immune system of an infected individual in ways that would enable the infected host to develop immune responses that clear reservoirs of persistent virus infection, effectively curing the host of infection. This concept was evaluated in rhesus macaques infected long term with rhesus cytomegalovirus by repeatedly immunizing infected animals with nonfunctional versions of the rhesus cytomegalovirus-encoded viral interleukin-10 immune-modulating protein. Following vaccine-mediated boosting of antibody titers to viral interleukin-10, there was modest evidence for increased immunological control of the virus following vaccination. More significantly, data were also obtained that indicated that rhesus cytomegalovirus is able to persist due to upregulation of the cellular interleukin-10 signaling pathway.

Do "birds of a feather flock together" or do "opposites attract"? Behavioral responses and temperament predict success in pairings of rhesus monkeys in a laboratory setting.

The growing recognition that social needs of primates in captivity must be addressed can present challenges to staff at primate facilities charged with implementing pair-housing solutions for animals. Unfortunately, there are few published papers that identify individual characteristics that might facilitate the social pairing process, and those that have looked at pre-pairing measures of behavior have produced mixed results. Using a database of n = 340 isosexual pairing attempts, we report that measures associated with responses to a standardized infant assessment protocol (the BioBehavioral Assessment program) predict success in pairing attempts that occurred years later. Behavioral responses to a brief separation and relocation, to a human intruder challenge, as well as ratings of temperament, were obtained from rhesus monkeys at 3-4 months of age. Logistic regression was used to identify potential predictors of success when animals were paired up to 10 years after the behavioral assessments. Among females, success was higher when members of a pair were more similar (i.e., a smaller difference scores) in patterns of emotional responding (Emotionality, Nervous temperament) during the infant assessments. In contrast, among males, success was higher when the pair had lower mean values for Gentle and Nervous temperament scores; when the members were younger; when pairs had a greater weight difference; and when they came from the same rearing background. Together, our results suggest that broad measures reflecting patterns of emotionality in response to challenge, which can be assessed in infancy (but which remain relatively stable throughout life) can be usefully employed to increase the likelihood of success in pairing attempts. Am. J. Primatol. 79:e22464, 2017. © 2015 Wiley Periodicals, Inc.

Cognitive reappraisal and expressive suppression: Links to racial-ethnic discrimination and adjustment among Latino/a and Asian-heritage college students.

OBJECTIVE: We examined whether two key emotion regulation strategies, cognitive reappraisal and expressive suppression, moderated the relations between discrimination (i.e., foreigner objectification and general denigration) and adjustment. METHODS: Participants were U.S. Latino/a and Asian-heritage college students (N = 1,279, 67% female, 72% U.S. born) from the Multi-Site University Study of Identity and Culture (MUSIC). Students completed online self-report surveys in 2009. RESULTS: Multi-group path analysis demonstrated that a fully constrained model fit well for both Latino/a and Asian-heritage student data. The results showed that with increasing levels of denigration (but not foreigner objectification), the combination of lower cognitive reappraisal and higher expressive suppression was related to greater depressive symptoms, anxiety, and aggression. CONCLUSIONS: Our findings highlight the importance of examining multiple emotion regulation strategies simultaneously-considering what strategies are available to individuals and in what combination they are used-to understand how best to deal with negative emotions resulting from experiencing discrimination.

A Note on Recurring Misconceptions When Fitting Nonlinear Mixed Models.

Nonlinear mixed-effects (NLME) models are used when analyzing continuous repeated measures data taken on each of a number of individuals where the focus is on characteristics of complex, nonlinear individual change. Challenges with fitting NLME models and interpreting analytic results have been well documented in the statistical literature. However, parameter estimates as well as fitted functions from NLME analyses in recent articles have been misinterpreted, suggesting the need for clarification of these issues before these misconceptions become fact. These misconceptions arise from the choice of popular estimation algorithms, namely, the first-order linearization method (FO) and Gaussian-Hermite quadrature (GHQ) methods, and how these choices necessarily lead to population-average (PA) or subject-specific (SS) interpretations of model parameters, respectively. These estimation approaches also affect the fitted function for the typical individual, the lack-of-fit of individuals' predicted trajectories, and vice versa.

Overcoming Clinical Inertia: A Randomized Clinical Trial of a Telehealth Remote Monitoring Intervention Using Paired Glucose Testing in Adults With Type 2 Diabetes.

BACKGROUND: Type 2 diabetes mellitus is a worldwide challenge. Practice guidelines promote structured self-monitoring of blood glucose (SMBG) for informing health care providers about glycemic control and providing patient feedback to increase knowledge, self-efficacy, and behavior change. Paired glucose testing­pairs of glucose results obtained before and after a meal or physical activity­is a method of structured SMBG. However, frequent access to glucose data to interpret values and recommend actions is challenging. A complete feedback loop­data collection and interpretation combined with feedback to modify treatment­has been associated with improved outcomes, yet there remains limited integration of SMBG feedback in diabetes management. Incorporating telehealth remote monitoring and asynchronous electronic health record (EHR) feedback from certified diabetes educators (CDEs)­specialists in glucose pattern management­employ the complete feedback loop to improve outcomes. OBJECTIVE: The purpose of this study was to evaluate a telehealth remote monitoring intervention using paired glucose testing and asynchronous data analysis in adults with type 2 diabetes. The primary aim was change in glycated hemoglobin (A(1c))­a measure of overall glucose management­between groups after 6 months. The secondary aims were change in self-reported Summary of Diabetes Self-Care Activities (SDSCA), Diabetes Empowerment Scale, and Diabetes Knowledge Test. METHODS: A 2-group randomized clinical trial was conducted comparing usual care to telehealth remote monitoring with paired glucose testing and asynchronous virtual visits. Participants were aged 30-70 years, not using insulin with A1c levels between 7.5% and 10.9% (58-96 mmol/mol). The telehealth remote monitoring tablet computer transmitted glucose data and facilitated a complete feedback loop to educate participants, analyze actionable glucose data, and provide feedback. Data from paired glucose testing were analyzed asynchronously using computer-assisted pattern analysis and were shared with patients via the EHR weekly. CDEs called participants monthly to discuss paired glucose testing trends and treatment changes. Separate mixed-effects models were used to analyze data. RESULTS: Participants (N=90) were primarily white (64%, 56/87), mean age 58 (SD 11) years, mean body mass index 34.1 (SD 6.7) kg/m2, with diabetes for mean 8.2 (SD 5.4) years, and a mean A(1c) of 8.3% (SD 1.1; 67 mmol/mol). Both groups lowered A(1c) with an estimated average decrease of 0.70 percentage points in usual care group and 1.11 percentage points in the treatment group with a significant difference of 0.41 percentage points at 6 months (SE 0.08, t159=-2.87, P=.005). Change in medication (SE 0.21, t157=-3.37, P=.009) was significantly associated with lower A(1c) level. The treatment group significantly improved on the SDSCA subscales carbohydrate spacing (P=.04), monitoring glucose (P=.001), and foot care (P=.02). CONCLUSIONS: An eHealth model incorporating a complete feedback loop with telehealth remote monitoring and paired glucose testing with asynchronous data analysis significantly improved A(1c) levels compared to usual care. TRIAL REGISTRATION: Clinicaltrials.gov NCT01715649; https://www.clinicaltrials.gov/ct2/show/NCT01715649 (Archived by WebCite at http://www.webcitation.org/6ZinLl8D0).

Fitting correlated residual error structures in nonlinear mixed-effects models using SAS PROC NLMIXED.

Nonlinear mixed-effects (NLME) models remain popular among practitioners for analyzing continuous repeated measures data taken on each of a number of individuals when interest centers on characterizing individual-specific change. Within this framework, variation and correlation among the repeated measurements may be partitioned into interindividual variation and intraindividual variation components. The covariance structure of the residuals are, in many applications, consigned to be independent with homogeneous variances, [Formula: see text], not because it is believed that intraindividual variation adheres to this structure, but because many software programs that estimate parameters of such models are not well-equipped to handle other, possibly more realistic, patterns. In this article, we describe how the programmatic environment within SAS may be utilized to model residual structures for serial correlation and variance heterogeneity. An empirical example is used to illustrate the capabilities of the module.

First-interview response patterns of intensive longitudinal psychological and health data.

Self-report data are essential in health psychology research where an individual's perception is critical to understanding one's health and psychological status. Intensive data collection over time, including daily diary assessments, is necessary in understanding within- and between-person variability in health and psychological processes over time. An "initial elevation or latent decline" (IELD) effect, inherent of self-report data, is increasingly acknowledged in the social psychology literature, but awareness of this effect in health psychology research is lacking, particularly in studies that emphasize within- and between-person variability in self-reports. The IELD effect is a pattern in which responses tend to be more extreme at the initial interview relative to subsequent responses. This paper illustrates the impact of IELD in applications of mixed-effects models based on observational self-reports and concludes that researchers take such effects into account in data analysis or in the research designing phase to help mitigate such effects.

Work related injury among aging women.

This article reports the experiences of women aged 55 to 75 with mobility impairments who attributed aspects of their limitations to workplace injuries and provides insight into worker's compensation policies. The study sample includes Mexican American (MA) and non-Hispanic White (NHW) women aged 55 to 75 who participated in a 4-year ethnographic study of disablement. Ninety-two of the 122 participants in the study attributed aspects of their functional limitations to employment, and their experiences were analyzed using data from 354 meetings. Using Lipscomb and colleagues' conceptual model of work and health disparities, the women's experiences were grouped into three categories according to type of injury, assistance gained, and the consequences of a workplace injury; the results have broad implications for policies that influence aging outcomes. Workplace injuries causing permanent functional limitations compound the effects of age and gender on employment outcomes. Policies addressing health disparities should consider work related influences.

Client predictors of short-term psychotherapy outcomes among Asian and white American outpatients.

PURPOSE: To examine predictors of psychotherapy outcomes, focusing on client characteristics that are especially salient for culturally diverse clients. METHOD: Sixty clients (31 women; 27 White Americans, 33 Asian Americans) participated in this treatment study. Client characteristics were measured at pretreatment, and outcomes were measured postfourth session via therapist ratings of functioning and symptomatology. Regression analyses were utilized to test for predictors of outcomes, and bootstrap analyses were utilized to test for mediators. RESULTS: Higher levels of somatic symptoms predicted lower psychosocial functioning at posttreatment. Avoidant coping style predicted more negative symptoms and more psychological discomfort. Non-English language preference predicted worse outcomes; this effect was mediated by an avoidant coping style. CONCLUSIONS: Language preference, avoidant coping style, and somatic symptoms predicted treatment outcome in a culturally diverse sample. Findings suggest that race/ethnicity-related variables may function through mediating proximal variables to affect outcomes.