multimorbidity

Multimorbidity is the co-occurrence of two or more chronic conditions in an individual. The term emphasizes the interaction of diseases within a person and differs from comorbidity, where one condition is primary and others are secondary to it. Chronic conditions may include cardiovascular disease, diabetes, cancer, chronic respiratory disease, kidney disease, mental health disorders, and musculoskeletal conditions. Multimorbidity is common in aging populations but occurs at younger ages in some groups and in settings with high disease burden.

Prevalence varies by population and definition. In high-income countries, estimates for adults over 65 typically exceed 60% with two or more chronic conditions; estimates for all adults range widely but commonly fall around 20–40%. Rates are rising with aging populations and improvements in survival for chronic diseases.

Impact: multimorbidity is associated with reduced quality of life, greater functional limitation, higher risk of adverse drug events, and increased hospitalizations and mortality. It also presents challenges for health systems, including higher medical costs and care coordination difficulties, as guidelines often target single diseases and polypharmacy hazards.

Management: effective care emphasizes patient-centered, coordinated, and continuous care. Approaches include comprehensive care plans, team-based care, shared decision making, deprescribing to minimize treatment burden, and lifestyle interventions. Decision support and electronic health records can aid integration.

Measurement and policy: research uses various definitions and indices; mainstream indices include counts of chronic conditions, approach to risk prediction, and patient-reported outcomes. Policy implications include the need for integrated care models, more inclusive clinical trials, and health system redesign to support coordinated care, data sharing, and preventive strategies.