A new approach for investigation of person-environment interaction effects in research involving health outcomes

Personal Competence or Environmental Characteristics? Factors Influencing Happiness among Ageing Adults in Hong Kong Around the Period of COVID-19 Pandemic

Drawing upon person-environment fit perspective, this study examines the joint and interactive influences of personal competence and environmental characteristics on the happiness of ageing adults around the period of COVID-19 pandemic. Data was collected in two rounds, before and during the pandemic, with 2,028 participants aged 55 years and older in Hong Kong. Personal competence encompassed financial status, physical health, and mental capital, while environmental characteristics included experiences of ageism, perceived social conditions, and age-friendly policies. Ordinary least squares regression was used to examine personal and environmental influences on happiness. Results indicated a significant decline in happiness following the onset of COVID-19 pandemic. Mental capital was found to have the strongest positive influence on happiness, followed by physical health, financial status, and social conditions. Mental capital mitigated the negative relationship between experiences of ageism and happiness. Practical interventions are informed to improve the well-being of ageing adults during pandemic.

A directed acyclic graph for interactions

BACKGROUND

Directed acyclic graphs (DAGs) are of great help when researchers try to understand the nature of causal relationships and the consequences of conditioning on different variables. One fundamental feature of causal relations that has not been incorporated into the standard DAG framework is interaction, i.e. when the effect of one variable (on a chosen scale) depends on the value that another variable is set to. In this paper, we propose a new type of DAG-the interaction DAG (IDAG), which can be used to understand this phenomenon.

METHODS

The IDAG works like any DAG but instead of including a node for the outcome, it includes a node for a causal effect. We introduce concepts such as confounded interaction and total, direct and indirect interaction, showing that these can be depicted in ways analogous to how similar concepts are depicted in standard DAGs. This also allows for conclusions on which treatment interactions to account for empirically. Moreover, since generalizability can be compromised in the presence of underlying interactions, the framework can be used to illustrate threats to generalizability and to identify variables to account for in order to make results valid for the target population.

CONCLUSIONS

The IDAG allows for a both intuitive and stringent way of illustrating interactions. It helps to distinguish between causal and non-causal mechanisms behind effect variation. Conclusions about how to empirically estimate interactions can be drawn-as well as conclusions about how to achieve generalizability in contexts where interest lies in estimating an overall effect.

Associations between individual factors, environmental factors, and outdoor independence in older adults

The degree to which individuals can accomplish outdoor activity by themselves or require support is an important facet of successful aging. While prior research focuses on participation in outdoor activity, understanding of older adults' outdoor independence is limited. We adopt an ecological approach to examine the role of individual factors and environmental factors in explaining outdoor independence. Our sample comprised older adults aged 65 + living in a medium-sized city in Germany (N = 1070). The results show that being male, younger, and healthier was positively associated with outdoor independence, while living together was not. Further, outdoor independence decreased with higher levels of perceived environmental barriers. This negative association was moderated such that it was stronger for the less healthy and older participants. Based on our empirical findings, we offer insights for policy makers, urban planners, and community groups to design age-friendly communities and consequently facilitate outdoor independence among older adults.

Longitudinal association between housing accessibility and activities of daily living: the role of self-efficacy and control in people ageing with Parkinson's disease

Background

External housing-related control beliefs (HCB) and general self-efficacy (GSE) influence different health outcomes in the general ageing population, but there is no information of their role in people ageing with Parkinson’s disease (PD). This study aimed to longitudinally assess the role of external HCB and GSE on the association between housing accessibility and activities of daily living (ADL) among people ageing with PD.

Methods

Baseline and 3-year follow-up data on 130 community-living participants from the Swedish project ‘Home and Health in People Ageing with PD’ were collected. Assessments addressed housing accessibility, external HCB, GSE, generic ADL and ADL specific to PD. The moderating effects of external HCB and GSE were assessed by including an interaction term in multivariable logistic regression.

Results

There were statistically significant interactions between housing accessibility and GSE on ADL (p = 0.03), and housing accessibility and external HCB on PD specific ADL (p = 0.03). After stratifying the analyses by GSE, housing accessibility problems led to more dependence and difficulty in ADL in participants with low GSE (OR 1.14; 95% CI 1.02–1.28). After stratifying by external HCB, housing accessibility increased dependence and difficulty in PD specific ADL in participants with low external HCB (OR 1.35; 95% CI 1.03–1.76).

Discussion

The results suggest that housing accessibility predicts ADL in people with PD with GSE and external HCB playing a moderating role for generic ADL and ADL specific to PD, respectively. Further longitudinal studies should validate these findings and explore their potential application in PD-related care and rehabilitation.