Multimorbidity, mortality, and physical activity

Area of Science:

• Public Health
• Epidemiology
• Gerontology

Background:

• Multimorbidity (the presence of multiple chronic diseases) is a significant risk factor for mortality.
• Physical inactivity is also independently linked to an increased risk of death.
• The interplay between physical activity and the mortality risk associated with multimorbidity remains under-explored.

Purpose of the Study:

• To investigate whether physical activity moderates the relationship between multimorbidity and all-cause mortality.
• To determine the extent of physical activity needed to potentially mitigate mortality risk in individuals with multiple health conditions.

Main Methods:

• Utilized data from 16,091 participants in the 1999-2006 National Health and Nutrition Examination Survey (NHANES).
• Followed participants through 2011, with a median follow-up of 99 months.
• Assessed physical activity through self-report and multimorbidity via physician diagnoses.

Main Results:

• Each additional morbidity increased the risk of all-cause mortality by 23% (HR=1.23).
• Multimorbidity remained associated with higher mortality risk across most physical activity levels.
• An exception was observed for individuals engaging in physical activity at four times the recommended government guidelines.

Conclusions:

• Physical activity generally has a minimal effect on the association between multimorbidity and mortality.
• Substantial engagement in physical activity (e.g., four times guideline dose) may be necessary to alter this relationship.
• Public health strategies should consider promoting very high levels of physical activity for individuals with multiple chronic conditions.