Development of a multimorbidity health conditions outcome index for caloric restriction interventional studies in older adults: a preliminary investigation in an observational cohort study

Using multiple sources, we provide the conceptual justification and statistical support for a multimorbidity outcome associated with obesity-related conditions, which we term the Health Conditions Index (HCI). This index was designed to capture the health effects of multi-year studies of caloric restriction for older adults with BMIs in the overweight or obesity classification. We used a subset of participants in the Health, Aging and Body Composition Cohort Study to evaluate multiple aspects of the index and its components over 5 years of follow-up. The 937 participants in the subset had an average age of 73 years and a BMI of 30.7 kg/m²; 53% were female and 43% were Black; 80% were hypertensive and 14% had type 2 diabetes. Results demonstrated that the components of the index were consistently related to initial BMI and percent body fat on cohort entry, generally showed an increasing prevalence over the 5-year follow-up, and, as a composite index, exhibited an association between faster progression and higher initial levels of age, BMI, and percent body fat. Further, the initial HCI was associated with a statistically significant increase in the rate of mortality over 5 years of follow-up (hazard ratio = 1.22, 95% CI 1.04 to 1.44). By using outcomes like the HCI, clinical trials of caloric restriction in older adults may gain a better understanding of how intentional weight loss relates to future risk of multiple chronic conditions associated with aging.