We then modeled these 12 binary indicators as a longitudinal
response in a logistic group-based trajectory model.
In a trajectory model, several regression models are
estimated simultaneously, including a multinomial logistic
model that estimates the probability of membership in
each group, and ordinary logistic models, which estimate
the probability of being adherent over time as a smooth
function of time. We estimated our model using 6 adherence
groups, which have been observed in prior research
to provide the best overall model fit