Modeling a Cross-Sectional Response Variable with Longitudinal Predictors: An Example of Pulse Pressure and Pulse Wave Velocity.

We wish to model pulse wave velocity (PWV) as a function of longitudinal measurements of pulse pressure (PP) at the same and prior visits at which the PWV is measured. A number of approaches are compared. First, we use the PP at the same visit as the PWV in a linear regression model. In addition, we also use the average of all available PP's as the explanatory variable in a linear regression model. Next, a two-stage process is applied. The longitudinal PP is modeled using a linear mixed-effects model. This modeled PP is used in the regression model to describe PWV. An approach for using the longitudinal PP data is to obtain a measure of cumulative burden, the area under the PP curve (AUC). This AUC is used as an explanatory variable to model PWV. Finally, a joint Bayesian model is constructed similar to the two-stage model.