Multimorbidity Combinations and Disability in Older Adults

Background: Multimorbidity (multiple co-occurring chronic diseases) is associated with greater likelihood of disability and mortality, above and beyond the risk attributable to individual diseases. This study identifies prevalent multimorbidity patterns and evaluates their association with disability among U.S. older adults. Methods: Prospective cohort study using longitudinal Health and Retirement Study data (2010-2012). We included 8,782 participants aged 65 years and older and used negative binomial models to examine prospective disability, measured by the combined activities of daily living-instrumental activities of daily living index. Multimorbidity was defined as the co-occurring combination of at least two of the following chronic diseases: hypertension, cardiovascular disease, lung disease, diabetes, cancer, arthritis, stroke, cognitive impairment, or high depressive symptoms (CES-D score ≥ 4). Results: We found 291 unique disease combinations with 1 to 1,167 older adults per disease combination. The three most prevalent combinations were: (a) hypertension and arthritis (n = 1,167); (b) hypertension, arthritis, and cardiovascular disease (n = 510); and (c) hypertension, arthritis, and diabetes (n = 430). Only one of the prevalent combinations included depressive symptoms (in combination with arthritis, hypertension; n = 129). This group showed the highest level of activities of daily living-instrumental activities of daily living disability compared to healthy participants or participants with a single disease (either included in the combination or different from diseases in the combination) even after adjusting for age, gender, education, race/ethnicity, and body mass index. Conclusions: Clinicians stand to gain from a better understanding of which disease combinations are more and less disabling among older adults. Understanding how multimorbidity combinations relate to functional status is an important step towards reducing disability and sustaining independent living among older adults.