O modelo de equações estruturais na análise de mediação

A descrição de fenômenos coletivos nas ciências da saúde e do comportamento abre portas para a análise de relações entre variáveis preditoras e de desfecho. Quando uma terceira variável é incluída na relação entre ambas, afetando ou intervindo indiretamente a sua relação frequentemente trata-se de uma variável mediadora. Quando uma variável mediadora é identificada, o efeito total da preditora no desfecho é decomposto em um efeito direto, e um efeito indireto. Diferentes métodos têm sido identificados para analisar a relação de mediação, e um destes é o modelo de equações estruturais. Este se torna uma técnica interessante no contexto da hipótese de mediação por ser uma técnica multivariada apropriada e eficiente para estimar, simultaneamente, várias equações de regressão interdependentes. Ele é composto por dois aspectos: o estrutural e o de mensuração; e é ilustrado por um diagrama de caminhos (path diagram). O modelo estrutural se refere à forma em que as variáveis se relacionam e o modelo de mensuração tem relação com a possiblidade de incluir variáveis latentes (variáveis não observadas que, também, são chamadas de constructos, não medidas diretamente, mas através de outras variáveis observadas) no modelo estrutural. O objetivo deste trabalho é descrever o modelo de equações estruturais como opção de método para a análise de relações entre preditora (ou preditoras) e desfecho na presença de hipótese mediacional desenvolvendo um guia ilustrado com um exemplo da área da saúde e utilizando o software R, particularmente o pacote Lavaan. São apresentados o caso de uma e de duas mediadoras (mediação simples e múltipla). O exemplo explorado avalia a relação dos maus-tratos na infância medidos através do instrumento Childhood Trauma Questionnaire (CTQ) e a depressão medida como uma variável latente (através de 10 itens da entrevista semi-estruturada Mini International Neuropsychiatric Interview 5.0 - MINI). A hipótese testada é de que a personalidade pode mediar esta relação. A personalidade é avaliada por traços que foram medidos através do NEO-Five Factor Inventory (NEO-FFI), um instrumento que avalia cinco tendências comportamentais das quais o Neuroticismo e a abertura à experiência foram as tendências exploradas como possíveis mediadoras. Os dados utilizados para ilustrar este trabalho são reais. A presença de mediação é um conceito teórico e deve ser explorado sempre que a teoria o aponte. O modelo de equações estruturais mostrou-se uma ferramenta apropriada e importante para a análise da relação entre preditora e desfecho, na presença de mediação simples, ou múltipla e o pacote Lavaan no R oferece recursos para desenvolver esta análise de forma adequada.The description of collective phenomena in the health and behavioral sciences opens the door to the analysis of a relationship between predictor and outcome variables. When a third variable is included and this change the way they relate, it is often called a mediating variable. When a mediator variable is identified, the overall effect of the predictor on the outcome is decomposed into a direct effect, and an indirect effect. Different methods have been identified to analyze the mediation relationship, and one of these is the Structural Equation Model. This becomes an interesting technique in the context of the mediation hypothesis because it is an appropriate and efficient multivariate technique to simultaneously estimate several interdependent regression equations. It is composed of two aspects: the structural and the measurement, illustrated by the path diagram. The structural model refers to the way in which the variables relate and the measurement model is related to the possibility of including latent variables (unobserved variables that are also called constructs, not measured directly, but through other observed variables) in the structural model. The aim of this work is to describe the Structural Equations model as a method option for the analysis of relations between predictors and outcome in the presence of mediation hypothesis, developing a famework illustrated with an example of the area of health in R software, particularly the Lavaan package. A practical example was used considering one and two mediators (simple and multiple mediation). In the example, the relationship between child maltreatment measured through the Childhood Trauma Questionnaire (CTQ) and Depression, measured as a latent variable (through several observed, 10 items in the Mini International Neuropsychiatric Interview 5.0 (MINI) questionnaire) is evaluated. Personality traits were measured through the NEO-Five Factor Inventory (NEO-FFI), an instrument that assesses five behavioral tendencies from which Neuroticism and the Openness to Experience were the exploited trends as possible mediators. The example is based in real data., The presence of mediation is a theoretical concept and should be explored whenever the theory points it out. The Structural Equations Model proved to be an appropriate and important tool for analyzing the relationship between predictor and outcome in the presence of simple or multiple mediation, and the Lavaan in R software offers the resources to develop this analysis adequately

Childhood trauma subtypes may influence the pattern of substance use and preferential substance in men with alcohol and/or crack-cocaine addiction

Objective: To compare the prevalence and subtypes of childhood maltreatment (CM) between individuals with and without substance use disorder (SUD) and investigate the influence of different traumas on the preferential use of substances and the severity of dependence. Methods: The sample consisted of 1,040 men with SUD (alcohol users [n=315], crack-cocaine users [n=406], multiple-substance users [n=319]) and 201 controls. The Childhood Trauma Questionnaire (CTQ) and the Addiction Severity Index-6 (ASI-6) were used to assess CM and drug-use patterns. Results: Individuals with SUD had a higher prevalence of CM than controls (63.4 vs. 28.1%, respectively). Exposure to physical trauma was associated with alcohol use disorder and severity of alcohol use. In contrast, emotional trauma was associated with use of multiple substances and severity of drug use in crack-cocaine users. Conclusions: This study corroborates the association of CM with SUD susceptibility. Our results suggest that the type of CM may influence preferential substance use and addiction severity. In this sense, physical traumas are more associated with alcohol use, while emotional and sexual traumas favor use of multiple drugs, especially crack cocaine. These findings may help the development of tailored prevention and intervention strategies

Age of Sexual Initiation, Psychiatric Symptoms, and Sexual Risk Behavior among Ecstasy and LSD Users in Porto Alegre, Brazil: A Preliminary Analysis

Ecstasy and LSD use is widespread in large Brazilian cities, but there is limited information on their use among young, middle-class, club goers in Brazil. We conducted standardized face-to-face interviews with 200 male and female ecstasy and/or LSD users, focusing on drug use and sexual history, current risk behaviors, and psychiatric symptomatology. Participants with early sexual debut (before 14) were more likely to report lifetime use of marijuana and powder and crack cocaine than those with later sexual initiation. Early sexual debut was associated with past year sexual risk behaviors, including having sex while high (Prevalence Ratio (PR)=1.3), having two or more sex partners (PR=1.3), as well as history of sexual abuse (PR=13.6). Depression and anxiety scores were similar by age of sexual initiation. The implications of these findings are discussed

The next pandemic : impact of COVID-19 in mental healthcare assistance in a nationwide epidemiological study

Background: Studies have reported the worsening of psychiatric symptoms during the COVID-19 pandemic. However, few studies have evaluated the impact on the access to mental health services during COVID-19. Our aim was to analyze temporal trends and prediction of appointments held in Brazil’s public health system, to compare the observed and expected number of mental healthcare appointments during the COVID-19 pandemics. Methods: An ecological time-series study was performed, analyzing mental health appointments before and during the pandemic (from 2016 and 2020) from the Brazilian governmental database. The structural break in the data series was assessed using the Chow test, with the break considered in March 2020. Bayesian structural time-series models were used to estimate current average appointments and the predicted expectation if there was no pandemic. Findings: Compared to the expected, between March and August 2020 about 28% less outpatient appointments in mental health were observed, totaling 471,448 individuals with suspended assistance. Group appointments and psychiatric hospitalizations were also severely impacted by the pandemic (decreased of 68% and 33%, respectively). On the other hand, mental health emergency consultations and home care increased during this period (36% and 52%, respectively). Interpretation: Our findings demonstrate a dramatic change in mental health assistance during the COVID-19 pandemic, which corroborates a recent WHO survey. This phenomenon can aggravate the mental health crisis and generate a parallel pandemic that may last for a longer time than the COVID-19 pandemic. Funding: This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) - Finance Code 001

Crack-cocaine users have less family cohesion than alcohol users

Objective: Many studies correlate characteristics of family functioning and the development of drug addiction. This study sought to evaluate and compare the family environment styles of two groups of psychoactive substance users: 1) alcohol-only users and 2) crack-cocaine users. Methods: Three hundred and sixty-four users of alcohol, crack-cocaine, and other drugs, recruited from research centers in four Brazilian capitals participated in this study. Subjects were evaluated through the Family Environment Scale and the Addiction Severity Index, 6th version (ASI-6). ASI-6 t-scores were compared by analysis of variance (ANOVA) and post-hoc tests. A final model was obtained using a logistic regression analysis. All analyses were adjusted for partner, age, and psychiatric t-score. Results: We found a significant difference between groups in the cohesion subscale (p = 0.044). The post-hoc test revealed a difference of 1.06 points (95%CI 0.11-2.01) between groups 1 (6.4560.28) and 2 (5.3860.20). No significant between-group differences were observed in the other subscales. However, categorical analyses of variables regarding family dynamic showed that crack users more often reported that sometimes people in their family hit each other (30.4% vs. 13.2%, p = 0.007) and that people in their family frequently compared each other regarding work and/or school achievement (57.2% vs. 42.6%, p = 0.041). Conclusion: These results suggest that families of crack-cocaine users are less cohesive than families of alcohol users. This type of family environment may affect treatment outcome, and should thus be adequately approached

We Are...Marshall, August 14, 2019

Objective: We investigate the quality of life (QoL) of subjects with alcohol abuse/dependence, and we focus on aspects that are associated with alcohol consumption. Methods: We included inpatients and outpatients (n=174) of an addiction treatment program. All of the patients had had problems related to alcohol within the last 30 days. We used the WHOQOL-BREF to measure the patients’ QoL, and we used the ASI-6 to investigate the severity of problems related to alcohol and substance use. The main outcome measures considered for the linear regression analyses were the WHOQOL-BREF domains. The independent factors were the scores in the ASI-6 areas. Results: We found a negative correlation between the WHOQOL-BREF and the ASI-6. Significant correlations were included in the multiple linear regression pattern, which considered p<0.05 to be the cut off of statistical significance. We examined the regression analyses between the ASI-6 summary scores and the WHOQOL-BREF domains using variables that presented statistical significance in the correlation analysis. All ASI-6 problem areas showed negative correlations with domains. Conclusion: The decrease in QoL was not directly linked to the severity of alcohol use but rather with its consequences. The ASI-6 medical area was associated with a lower QoL in all of its domains. Measures of the problems related to alcohol misuse seem to be a significant predictor of QoL scores; the more often that alcohol is a problem in a patient’s life, the worse the patient’s QoL will be. Instead of treatment, other strategies should be developed to address these problem areas to not only reduce substance use but also to significantly improve the QoL of alcoholics