Clinical Characteristics and Health Outcomes of Working-Age Adults (18–64 Years) in General Medical Practice: A Synthesis of Primary-Care Evidence

Abstract

Background. Chronic disease and multimorbidity are usually framed as problems of old age, yet a large and growing share of the burden falls on working-age adults (18–64 years), in whom illness intersects with employment, income, and family responsibility. General practice is the principal setting in which this population is managed, but its distinctive clinical profile is comparatively neglected.

Objective. To synthesise published evidence on the clinical characteristics, prevalent conditions, and health outcomes of working-age adults in general practice, with particular attention to multimorbidity, mental–physical comorbidity, the social gradient, and the consequences for work and productivity.

Methods. We conducted a structured synthesis of peer-reviewed primary-care epidemiology and population studies, prioritising analyses that disaggregate the working-age group, including large electronic-health-record and community cohorts and productivity-cost studies.

Results. Although multimorbidity prevalence rises with age, in absolute numbers more people with multimorbidity are below 65 than above it. Prevalence among middle-aged adults (45–64) is substantial—around 30% in Scottish primary-care data—and in deprived areas multimorbidity appears 10–15 years earlier, so that disadvantaged working-age adults carry a burden equivalent to affluent people a decade or more older. Depression and anxiety are especially prominent in this group, particularly among the unemployed, and musculoskeletal conditions are common. Multimorbidity in employed adults is associated with markedly increased work absence—rising from around 5–6 days a year with no or one condition to over 30 days with four or more.

Conclusion. Working-age adults in general practice represent a large, socially patterned, and economically consequential group in whom early, equity-focused, and work-aware chronic-disease care could yield substantial individual and societal benefit.