group based trajectory modelling

Dear all,

Any thoughts....?

I have longitudinal biomarker data that is routinely gathered, so will not be at specific time points. I want to identify trajectories of biomarkers in a disease to identify subpopulations that might have increased risk of adverse outcomes compared to other trajectory groups. My concern is that this model requires specific time points of biomarker observations for all subjects in order to work?

Any thoughts or suggestions would be appreciated