Trajectory classes of body mass index in a representative elderly community sample

Area of Science:

• Gerontology
• Epidemiology
• Public Health

Background:

• The existence of distinct weight-related trajectory classes in the elderly population, differing in course, demographics, and health characteristics, remains unclear.
• Understanding these trajectories is crucial for targeted health interventions in aging populations.

Purpose of the Study:

• To identify distinct body mass index (BMI) trajectory classes in an elderly population.
• To examine the demographic and health characteristics associated with these BMI trajectories.
• To determine the course and health implications of different BMI trajectories over a 10-year period.

Main Methods:

• Utilized data from 3,861 participants (aged 65-105) in the Duke Established Populations for Epidemiologic Studies of the Elderly study (1986-1996).
• Employed generalized mixture models to determine latent-class trajectories of BMI based on self-reported weight and height over 10 years.
• Used polytomous logistic regression to identify baseline demographic and health factors distinguishing trajectories and confirmed findings with 10-year postbaseline data.

Main Results:

• Identified three distinct BMI trajectories: normal weight (BMI ~24, 27.6%), overweight (BMI ~26, 65.1%), and obese (BMI ~31, 7.3%).
• Obese trajectory was associated with higher odds of Black individuals, women, and lower education levels. Normal-weight trajectory had the lowest odds for these characteristics.
• Adverse health outcomes like cognitive impairment, hypertension, and diabetes were more common in overweight and obese groups compared to normal-weight, but not significantly different between overweight and obese groups. Depressive symptomatology was more prevalent in the obese group, who were also younger.

Conclusions:

• Distinct BMI trajectories and courses are present in the elderly population, with weight loss increasing across BMI classes.
• While demographic factors differentiated all trajectory classes, adverse health characteristics distinguished overweight and obese classes from the normal-weight class, but not from each other.
• Health and educational disparities associated with BMI trajectories are evident at study entry, suggesting the need for earlier life interventions.