Alternative causal inference methods in population health research: Evaluating tradeoffs and triangulating evidence.

Population health researchers from different fields often address similar substantive questions but rely on different study designs, reflecting their home disciplines. This is especially true in studies involving causal inference, for which semantic and substantive differences inhibit interdisciplinary dialogue and collaboration. In this paper, we group nonrandomized study designs into two categories: those that use confounder-control (such as regression adjustment or propensity score matching) and those that rely on an instrument (such as instrumental variables, regression discontinuity, or differences-in-differences approaches). Using the Shadish, Cook, and Campbell framework for evaluating threats to validity, we contrast the assumptions, strengths, and limitations of these two approaches and illustrate differences with examples from the literature on education and health. Across disciplines, all methods to test a hypothesized causal relationship involve unverifiable assumptions, and rarely is there clear justification for exclusive reliance on one method. Each method entails trade-offs between statistical power, internal validity, measurement quality, and generalizability. The choice between confounder-control and instrument-based methods should be guided by these tradeoffs and consideration of the most important limitations of previous work in the area. Our goals are to foster common understanding of the methods available for causal inference in population health research and the tradeoffs between them; to encourage researchers to objectively evaluate what can be learned from methods outside one's home discipline; and to facilitate the selection of methods that best answer the investigator's scientific questions

Implications of Lifecourse Epidemiology for Research on Determinants of Adult Disease

Many diseases commonly associated with aging are now thought to have social and physiologic antecedents in early life. Understanding how the timing of exposure to early life risk factors influences later-life health may illuminate mechanisms driving adult health inequalities and identify possible points for effective interventions. Recognizing chronic diseases as developing across the lifecourse also has implications for the conduct of research on adult risk factors for disease. We review alternative conceptual models that describe how the timing of risk factor exposure relates to the development of disease. We propose some expansions of lifecourse models to improve their relevance for research on adult chronic disease, using the relationship between education and adult cognitive decline and dementia as an example. We discuss the important implications each of the lifecourse conceptual models has on study design, analysis, and interpretation of research on aging and chronic diseases. We summarize several research considerations implied by the lifecourse framework, including: advantages of analyzing change in function rather than onset of impairment; the pervasive challenge of survivor bias; the importance of controlling for possible confounding by early life conditions; and the likely heterogeneity in responses of adults to treatment

El Pla Territorial de l'illa de Menorca

El Pla Territorial de Menorca és un exemple d’aplicació dels criteris de desenvolupament sostenible a la realitat territorial de l’Illa. Aquests criteris condueixen tot el procés planificador i troben un bon suport en la societat menorquina, que és ben conscient de la qualitat, i també de la fragilitat, del seu territori. Menorca opta així per un model territorial diferenciat que pretén fer compatible economia i respecte als recursos naturals i al paisatge. El Pla introdueix mesures de protecció sobre la totalitat del sòl rústic, per tal de preservar la diversitat d’àmbits rurals, tant naturals com humanitzats, tots ells amb valor paisatgístic remarcable. Amplia els espais naturals protegits, de tal manera que es passa de tenir una sèrie inconnexa d’espais naturals protegits a establir un vertader sistema d’espais naturals protegits. Limita el creixement de les zones turístiques, a fi que aquestes puguin ser reconduïdes a paràmetres de més qualitat i preveu un desenvolupament harmònic dins els nuclis tradicionals de població

Does schooling attained by adult children affect parents' psychosocial well-being in later life? Using Mexico's 1993 compulsory schooling law as a quasi-experiment

Higher adult child educational attainment may benefit older parents' psychosocial well-being in later life. This may be particularly important in low- and middle-income countries, where recent generations have experienced comparatively large increases in educational attainment. We used data from the 2012 Mexican Health and Aging Study, a nationally representative study of adults aged ≥50 years and leveraged the exogenous variation in adult child education induced by Mexico's compulsory schooling law passed in 1993. We employed two-stage least squares (2SLS) regression to estimate the effects of increased schooling among adult children on parents' (respondents') depressive symptoms and life satisfaction scores, controlling for demographic and socioeconomic characteristics. We considered heterogeneity by parent and child gender and other sociodemographic characteristics. Our study included 7186 participants with an average age of 60.1 years; 54.9% were female. In the 2SLS analyses, increased schooling among oldest adult children was associated with fewer depressive symptoms (β = −0.25; 95% CI: −0.51, 0.00) but no difference in life satisfaction (β = 0.01; 95% CI: −0.22, 0.25). Stratified models indicated differences in the magnitude of association with depressive symptoms for mothers (β = −0.27, 95% CI: −0.56, 0.01) and fathers (β = −0.18, 95% CI: −0.63, 0.26) and when considering increased schooling of oldest sons (β = −0.37; 95% CI: −0.73, −0.02) and daughters (β = −0.05, 95% CI: −0.23, 0.13). No parent and child gender differences were found for life satisfaction. Power was limited to detect heterogeneity across other sociodemographic characteristics in the second stage although first-stage estimates were larger for urban (vs. rural) dwelling and more (vs. less) highly educated respondents. Results were similar when considering the highest educated child as well as increased schooling across all children. Our findings suggest that longer schooling among current generations of adult children, particularly sons, may benefit their older parents' psychosocial well-being

Type of High-School Credentials and Older Age ADL and IADL Limitations: Is the GED Credential Equivalent to a Diploma?

Purpose: Educational attainment is a robust predictor of disability in elderly Americans: older adults with high-school (HS) diplomas have a substantially lower disability than individuals who did not complete HS. General Educational Development (GED) diplomas now comprise almost 20% of new HS credentials issued annually in the United States but it is unknown whether the apparent health advantages of HS diplomas extend to GED credentials. This study examines whether adults older than 50 years with GEDs have higher odds of incident instrumental or basic activities of daily living (IADLs) limitations compared with HS degree holders. Methods: We compared odds of incident IADL limitations by HS credential type using discrete-time survival models among 9,426 Health and Retirement Study participants followed from 1998 through 2008. Results: HS degree holders had lower odds of incident IADLs than GED holders (OR = 0.72, 95% CI = 0.58, 0.90 and OR = 0.69, 95% CI = 0.56, 0.86 for ADLs and IADLs, respectively). There was no significant difference in odds of incident IADL limitations between GED holders and respondents without HS credentials (OR = 0.89, 95% CI = 0.71, 1.11 for ADLs; OR = 0.88, 95% CI = 0.70, 1.12 for IADLs).Implications: Although GEDs are widely accepted as equivalent to high school diplomas, they are not associated with comparable health advantages for physical limitations in older age

Childhood adversity and asthma prevalence: evidence from 10 US states (2009–2011)

Background: Existing evidence on stress and asthma prevalence has disproportionately focused on pregnancy and postpregnancy early life stressors, largely ignoring the role of childhood adversity as a risk factor. Childhood adversity (neglect, stressful living conditions and maltreatment) may influence asthma prevalence through mechanisms on the hypothalamic-pituitary axis. Methods: Data from the Center for Disease Control's (CDC's) Behavioral Risk Factor Surveillance System (BRFSS) surveys were used to examine cross-sectional associations of adverse childhood experiences (ACE) with lifetime and current asthma prevalence. Information on childhood adversity was available from 84 786 adult respondents in 10 US states. Poisson regression models (with robust SE) were used to estimate prevalence ratios (PRs) relating overall ACE score and dimensions of exposure ACE to asthma prevalence, adjusting for socioeconomic status. Results: Greater ACE was associated with a higher prevalence of asthma (adjusted PRcat 4=1.78 (95% CI 1.69 to 1.87), adjusted PRcat 1=1.21 (95% CI 1.16 to 1.27)). Reported experiences of sexual abuse (adjusted PR=1.48* (1.42 to 1.55)) and physical abuse (adjusted PR=1.38* (1.33 to 1.43)) were associated with a higher asthma prevalence. No clear socioeconomic gradient was noted, but those reporting lowest education and income levels reported high rates of asthma and adversity. Sensitivity analyses indicated that ACE exposures were interrelated. Conclusions: Report of childhood adversity predicts asthma prevalence among US adults. Frameworks for asthma prevention need to recognise and integrate aspects related to childhood adversity. Further investigation into specific time periods of exposure would provide meaningful inferences for interventions

Economic inequalities in the effectiveness of a primary care intervention for depression and suicidal ideation.

BACKGROUND: Economic disadvantage is associated with depression and suicide. We sought to determine whether economic disadvantage reduces the effectiveness of depression treatments received in primary care. METHODS: We conducted differential-effects analyses of the Prevention of Suicide in Primary Care Elderly: Collaborative Trial, a primary-care-based randomized, controlled trial for late-life depression and suicidal ideation conducted between 1999 and 2001, which included 514 patients with major depression or clinically significant minor depression. RESULTS: The intervention effect, defined as change in depressive symptoms from baseline, was stronger among persons reporting financial strain at baseline (differential effect size = -4.5 Hamilton Depression Rating Scale points across the study period [95% confidence interval = -8.6 to -0.3]). We found similar evidence for effect modification by neighborhood poverty, although the intervention effect weakened after the initial 4 months of the trial for participants residing in poor neighborhoods. There was no evidence of substantial differences in the effectiveness of the intervention on suicidal ideation and depression remission by economic disadvantage. CONCLUSIONS: Economic conditions moderated the effectiveness of primary-care-based treatment for late-life depression. Financially strained individuals benefited more from the intervention; we speculate this was because of the enhanced treatment management protocol, which led to a greater improvement in the care received by these persons. People living in poor neighborhoods experienced only temporary benefit from the intervention. Thus, multiple aspects of economic disadvantage affect depression treatment outcomes; additional work is needed to understand the underlying mechanisms