Individual Heterogeneity in the Probability of Hospitalization, Skilled Nursing Facility Admission, and Mortality.

Background: Multimorbidity is common in adults aged 65 and older and is associated with health care utilization and mortality, but most methods ignore the interrelationship among concurrent outcome nor provide person-specific probabilities.

Method: A longitudinal cohort of 5300 older Americans from the 2011-2015 rounds of the National Health and Aging Study was linked to Center for Medicare and Medicaid Services claims. Odds ratios for 15 chronic conditions adjusted for sociodemographic factors were estimated using a joint model of hospitalization, skilled nursing facility (SNF) admission, and mortality. Additionally, we estimated the person-specific probability of an outcome while currently at risk for other outcomes for different chronic disease combinations demonstrating the heterogeneity across persons with identical chronic conditions.

Results: During the 4-year follow-up period, 2867 (54.1%) individuals were hospitalized, 1029 (19.4%) were admitted to a SNF, and 1237 (23.3%) died. Chronic kidney disease, dementia, heart failure, and chronic obstructive pulmonary disease had significant increased odds for all 3 outcomes. By incorporating a person-specific random intercept, there was considerable range of person-specific probabilities for individuals with hypertension, diabetes, and depression with dementia, (hospitalization: 0.14-0.61; SNF admission: 0.04-0.28) and without dementia (hospitalization: 0.07-0.44; SNF admission: 0.02-0.15). Such heterogeneity was found among individuals with heart failure, ischemic heart disease, chronic kidney disease, hypertension, hyperlipidemia, and osteoarthritis with and without Medicare.

Conclusions: This approach of joint modeling of interrelated concurrent health care and mortality outcomes not only provides a cohort-level odds and probabilities but addresses the heterogeneity among otherwise similarly characterized persons identifying those with above-average probability of poor outcomes.