Background: The prevalence of obesity in older adults is increasing. Though body mass index (BMI) is often used as a measure of obesity, waist circumference (WC) may be a better reflection of obesity in older adults. While many factors contribute to transitioning to assisted living services (TALS), the relationship between obesity and TALS has demonstrated inconsistent results. This study aims to further understand the relationship between these anthropometric measures and incident TALS.
Methods: This analysis is based on longitudinal data from the National Health and Aging Trends Study (NHATS). Obesity was defined as BMI ≥ 30 kg/m2 and WC ≥ 88 cm in women or ≥ 102 cm in men, and further classified as class 1 (BMI 30–34.9 kg/m2), class 2 (35–39.9), and class 3 (40+) TALS was determined based on changes to residence throughout up to 10 study rounds. Participants without BMI or WC available and those in nursing homes or residential care facilities at the onset of the study were excluded. Separate proportional hazards models evaluated the risk of TALS using BMI and WC as primary predictors, after adjusting for demographics and comorbidities.
Results: The resultant analytic cohorts included n = 11,111 and n = 10,374 participants with BMI and WC data, respectively. Rates of TALS were 25.7% in the entire study cohort: 24.9% in the BMI and 23.9% in the WC cohort. Using BMI, adjusted risk of TALS was HR 1.31 (95% CI: 0.95–1.79) for underweight, HR 0.74 (0.65–0.85) for overweight, HR 0.71 (0.59–0.85) for class 1 obesity, HR 0.58 (0.42–0.80) for those with class 2 obesity, and HR 0.69 (0.44–1.08) for those with class 3 obesity or higher. With elevated WC, TALS risk was HR 0.98 (0.86–1.12).
Conclusions: Overweight, class 1, and class 2 obesity using BMI criteria were protective against TALS. Further study is needed to elucidate the underlying reasons for this protective effect against TALS.
