A gentle introduction to instrumental variables

Instrumental variables (IV) is a central strategy for identifying causal effects in absence of randomized experiments. Clinicians and epidemiologists may find the intuition of IV easy to grasp by comparison to randomized experiments. Randomization is an ideal IV because treatment is assigned randomly, and hence unaffected by everything else. IV methods in nonexperimental settings mimic a randomized experiment by using a source of “as good as” random variation in treatment instead. The main challenge with IV designs is to find IVs that are as good as randomization. Discovering potential IVs require substantive knowledge and an understanding of design principles. Moreover, IV methods recover causal effects for a subset of the population who take treatment when induced by the IV. Sometimes these estimates are informative, other times their relevance is questionable. We provide an introduction to IV methods in clinical epidemiology. First, we introduce the main principles and assumptions. Second, we present practical examples based on Mendelian randomization and provider preference and refer to other common IVs in health. Third, practical steps in IV analysis are presented. Fourth, the promise and perils of IV methods are discussed. Finally, we suggest further readings.publishedVersio

Preadolescents with immigrant backgrounds: the relationship between emotional problems, parental achievement values, and comparison

Although strong parental achievement values have been associated with positive outcomes among children (e.g., academic success), they have also been connected to emotional problems. The latter effect may be the result of pressure related to such things as parental comparison of filial achievement, which appears to be more predominant among immigrant parents as compared with non-immigrant parents.Our goals were to assess the following: 1) whether higher levels of parental achievement values and comparison are found among immigrant preadolescents; and (2) whether comparison (i.e., comparing a child's achievements with those of siblings and peers) can account for the link between strong parental achievement values and emotional problems among the children of immigrants.The sample included 902 preadolescents between the ages of 10 and 12 years from two Norwegian cities: Oslo (79%) and Bergen (21%). Forty-seven percent of the sample had immigrant parents, and the others had non-immigrant parents. A self-administered questionnaire was completed by fifth, sixth, and seventh graders from fourteen schools during normal school hours; the questionnaires were completed after school by students from Turkey and Sri Lanka. The questionnaire included measures of emotional problems, parental achievement values, comparison, and school hassles. We used a moderated mediation model to test whether the relationship between parental achievement values and emotional problems was accounted for by comparison and to look at whether this mediation was stronger for preadolescents with immigrant backgrounds as compared with their non-immigrant peers. Background and academic factors that could confound the unique relationships among the main variables were adjusted for in the analyses.The association between parental achievement values and emotional problems was found to be mediated by comparison. Higher levels of parental achievement values were associated with more comparison, and this relationship was stronger for preadolescents with immigrant backgrounds. Comparison was only linked to emotional problems in preadolescents with immigrant backgrounds.This study suggests that stronger parental achievement values among immigrants as compared with non-immigrants in Norway are found as early as preadolescence and that comparison may be part of the link between strong parental achievement values and emotional problems

Socioeconomic disparities in early language development in two Norwegian samples

Socioeconomic disparities in early language are widespread and have long-lasting effects. The aim of this study is to investigate when social gaps in language problems arise and how they change across the first years of schooling. We address this question in two large longitudinal Norwegian datasets: the Behavior Outlook Norwegian Developmental Study (BONDS) and the Norwegian Mother, Father and Child Cohort Study (MoBa). Despite some slight differences across the two samples, we found that children from higher social backgrounds are less likely to have language difficulties starting from age 18 months and up to age 8 (grade 2). Moreover, while early language problems are strongly predictive of later language, maternal education makes an additional contribution to explaining language difficulties at the beginning of school life. Social inequality in language development arises early, even in a country like Norway, with low unemployment and one of the most egalitarian societies in Europe.info:eu-repo/semantics/acceptedVersio

Variation in attitudes toward diagnosis and medication of ADHD: a survey among clinicians in the Norwegian child and adolescent mental health services

Prevalence and medication rates of ADHD vary geographically, both between and within countries. No absolute cutof exists between ADHD and normal behavior, making clinician attitudes (leading to local practice cultures) a potential explanation for the observed variation in diagnosis and medication rates. The objective of this study was to describe variation in attitudes toward diagnosis and medication of ADHD among clinicians working in child and adolescent mental health services (CAMHS). We hypothesized that attitudes would vary along a spectrum from “restrictive” to “liberal”. We also explored whether diferences in attitudes between clinicians were related to professional background and workplace (clinic). A survey in the form of a web-based questionnaire was developed. All CAMHS outpatient clinics in Norway were invited. Potential respondents were all clinicians involved in diagnosing and treating children and adolescents with ADHD. To investigate the existence of attitudes toward diagnosis and medication as latent constructs, we applied confrmatory factor analysis (CFA). We further examined how much of variance in attitudes could be ascribed to profession and clinics by estimating intraclass correlation coefcients. In total, 674 respondents representing 77 (88%) of the clinics participated. We confrmed variation in attitudes with average responses leaning toward the “restrictive” end of the spectrum. CFA supported “attitude toward diagnosis” and “attitude toward medication” as separate, and moderately correlated (r=0.4) latent variables, representing a scale from restrictive to liberal. Professional background and workplace explained only a small part of variance in these attitudes

Preference-based instrumental variables in health research rely on important and underreported assumptions: a systematic review

Objective: Preference-based instrumental variables (PP IV) designs can identify causal effects when patients receive treatment due to variation in providers’ treatment preference. We offer a systematic review and methodological assessment of PP IV applications in health research. Study Design and Setting: We included studies that applied PP IV for evaluation of any treatment in any population in health research (PROSPERO: CRD42020165014). We searched within four databases (Medline, Web of Science, ScienceDirect, SpringerLink) and four journals (including full-text and title and abstract sources) between January 1, 1998, and March 5, 2020. We extracted data on areas of applications and methodology, including assumptions using Swanson and Hernan’s (2013) guideline. Results: We included 185 of 1087 identified studies. The use of PP IV has increased, being predominantly used for treatment effects in cancer, cardiovascular disease, and mental health. The most common PP IV was treatment variation at the facility-level, followed by physician- and regional-level. Only 12 percent of applications report the four main assumptions for PP IV. Selection on treatment may be a potential issue in 46 percent of studies. Conclusion: The assumptions of PP IV are not sufficiently reported in existing work. PP IV studies should use reporting guidelines

Social and genetic associations with educational performance in a Scandinavian welfare state

Recent research has suggested that across Western developed societies, the influence of genetics on educational outcomes is relatively constant. However, the degree to which family environment matters varies, such that countries with high levels of intergenerational mobility have weaker associations of family background. Research in this vein has relied on twin-based estimates, which involve variance decomposition, so direct assessment of the association of genes and environments is not possible. In the present study, we approach the question by directly measuring the impact of child genotype, parental genetic nurture, and parental realized education on educational achievement in primary and secondary school. We deploy data from a social democratic context (Norway) and contrast our findings with those derived from more liberal welfare state contexts. Results point to genetics only confounding the relationship between parent status and offspring achievement to a small degree. Genetic nurture associations are similar to those in other societies. We find no, or very small, gene–environment interactions and parent–child genotype interactions with respect to test scores. In sum, in a Scandinavian welfare state context, both genetic and environmental associations are of similar magnitude as in societies with less-robust efforts to mitigate the influence of family background.publishedVersio

Attachment in middle and late childhood : measurement validation and relation to mental health problems

Attachment theory is a widely appreciated perspective on the importance of close relationships for human development. Middle and late childhood (8 to 13 years) is one of the least studied age periods in attachment research. Challenges for attachment research in general, and this age period in particular, concern the adequacy of measurement procedures and the influence of attachment on mental health problems. This dissertation includes cross-sectional data from 150 children (M age 11.7) and 121 parents. Children were interviewed with the Child Attachment Interview (CAI), which is videotaped and coded according to a manual. Both parents and children completed questionnaires including measures of mental health problems, as well as risk and protective factors for mental health problems. Individual differences in attachment are traditionally conceived of in terms of categories (e.g. secure-insecure). Yet, there are both theoretical and empirical reasons to consider individual differences as being distributed along dimensions. Furthermore, attachment researchers have to a limited extent taken advantage of recent developments in psychometrics, in particular a latent variable approach like Confirmatory Factor Analysis (CFA), to study construct validity. The first paper in this dissertation applies a CFA to the CAI, and thereby examines the construct validity of a continuous conception of the attachment construct in middle and late childhood. In this study, we found evidence for a two-dimensional model comprising the factors Security-Dismissal and Preoccupation-Idealization. Furthermore, we found these factors to maintain the information inherent in the categories, but to add information about subtle differences between individuals. The continuous approach to the attachment construct was applied in the two other papers in this dissertation as well. A small, yet consistent, association is found between attachment and mental health problems across age groups; insecurity as a risk factor, and security as a protective factor. More complex models are used to understand the role of attachment and other risk and protective factors for mental health problems. The multi-variate risk factor model where attachment, family adversity, and ineffective parenting are considered, alone and in combinations, to influence mental health problems, has been influential. The diathesis-stress model is another influential way of understanding how attachment influences mental health problems. This model is based on a stress-regulatory approach to attachment, and hypothesizes that children with high levels of attachment security have more efficient means IV for coping with stress. In contrast, children with low levels of attachment security (i.e. attachment insecurity) have less efficient means. In paper two, we combine these perspectives by hypothesizing attachment as a part of a multi-variate model of family risks, however as being a moderator of the negative effect of the other risk factors on internalizing and externalizing problems. This hypothesis was supported for some, but not all, of the risk factors. Also, there was a dose-response relationship between a cumulative index of risk factors and mental health problems for children with low levels of attachment security, whereas children with high levels of security were unaffected by the accumulation of family risks. The association between low levels of attachment security (i.e. insecure attachment) and internalizing problems is unquestionable. However, there are children who have more or less internalizing problems than expected, given their level of attachment security. The purpose of paper three is to examine characteristics of these children. We found high levels of difficult temperament (negative emotionality and shyness), as well as family risks, to characterize children with more internalizing problems than expected, given their level of security. Low levels of difficult temperament and family risks, but not positive temperament (activity) and social support from peers, explained less internalizing problems than expected, given the child’s level of attachment security. This dissertation addressed several important topics in attachment research, particularly concerning middle and late childhood. The main findings in this dissertation are: - Attachment organization, measured with the Child Attachment Interview, may adequately be conceived as a two-dimensional construct, however with one main dimension ranging from security to dismissal - Attachment security buffers the negative effects of family risk of mental health problems in middle and late childhood. - Children with more internalizing problems than expected, given their level of attachment security, tend to have difficult temperament and experience family risks

Concern Over Internal, External, and Incidence Validity in Studies of Child-Care Quantity and Externalizing Behavior Problems

Literature reviews have concluded that extensive time in early child care is associated with frequent externalizing behavior problems in children. In this article, we address three domains of validity in the work underlying these conclusions: internal, external, and incidence validity. Regarding internal validity, most studies rely on covariate‐adjusted correlations, an approach that is especially vulnerable to selection bias. In studies using more rigorous approaches to reduce selection bias, results are mixed and often inconsistent with the hypothesis that a high quantity of child care causes externalizing problems. Regarding external validity, the field has relied too heavily on U.S. samples. We call for more international replications to allow for sociopolitical variations. Regarding incidence validity, study designs have the widest relevance when structured to address the opportunities and constraints families face today. We suggest researchers ask questions about child‐care quantity that maximize validity in these three domains

Taking Selection Seriously in Correlational Studies of Child Development: A Call for Sensitivity Analyses

Correlational studies have played a major role in building our cumulative knowledge on child development. Yet as a result, we often have difficulty making causal inferences. The concern is selection effects: When children have not been randomly assigned to conditions, pre-existing biological, psycho- logical, or social factors may bias correlations. In this article, we draw attention to sensitivity analyses, statis- tical techniques for estimating the robustness or fragility of results in light of potential selection effects. We high- light the coefficient of proportionality method recently developed by Oster (2019), which does not require assumptions about the number of omitted selection vari- ables. The coefficient of proportionality provides an indication of how large the impact of unobserved selec- tion factors would need to be—relative to observed covariates—to nullify a result. We offer two empirical examples to demonstrate the value of this method com- pared with other approaches used by child development researchers