Joint Multivariate Response Modeling for Repeated BMI Measures and Single Measures of Adult Cardiovascular Disease Risk Factors

Studies of the association between developmental trajectories and adult health require methods relating developmental measures from different life stages to single measures of health outcomes. We present a joint multivariate response model to a longitudinal response variable, body mass index (BMI), and two single measure adult outcomes - systolic blood pressure (SBP) and high density lipoprotein cholesterol (HDL-C), to investigate the association between BMI trajectories and adult cardiovascular disease (CVD) risk factors. We adopt a linear spline model for repeated BMI measures to allow for distinct childhood and adult curves and separate models for SBP and HDL-C. The models are fitted simultaneously by assuming the joint distribution of random coefficients. The model is applied to the 1958 British Birth Cohort (n=17,000), whose BMI was recorded at six ages from 7 to 45y (16,820 with one or more measures) and SBP and HDL-C were measured at 45y. Results show that the rate of BMI gain in adulthood has a stronger association with SBP and HDL-C than the rate of BMI growth in childhood (p