Spousal epidemiology: a conceptual framework for interdependent health in couples

Epidemiology has traditionally treated individuals as independent units, potentially overlooking relational dynamics that shape health. In this paper, we propose a conceptual framework—spousal epidemiology—to characterise interdependent health processes in couples. Partner relationships, characterised by shared environments, lifestyle practices and reciprocal health influences, are enduring and highly interdependent. Spousal epidemiology reconceptualises couples as a unit of inference, moving beyond documenting spousal concordance to understand how health risks emerge, interact and accumulate dyadically over the life course. Spousal similarities arise through assortative mating and shared environments. Within this context, behavioural convergence, health spillover and role transitions shape interdependent health trajectories. To rigorously examine these processes, dyadic analytical approaches, such as the Actor–Partner Interdependence Model, can be applied. Ignoring partner interdependence may bias risk estimates and limit interventional effectiveness. Explicitly incorporating couples as analytical units supports novel research designs, partner-focused interventions and integration of relational data into public health surveillance. By explicitly incorporating interdependence, spousal epidemiology offers a pathway to more effective and scalable prevention strategies across populations.