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Joint Progression Modeling (JPM): A Probabilistic Framework for Mixed-Pathology Progression
Proceedings of the Fifth Machine Learning for Health Symposium, PMLR 297:1467-1515, 2026.
Abstract
Event-based models ({EBM}s) infer disease progression from cross-sectional data, and standard {EBM}s assume a single underlying disease per individual. In contrast, mixed pathologies are common in neurodegeneration. We introduce the Joint Progression Model ({JPM}), a probabilistic framework that treats single-disease trajectories as partial rankings and builds a prior over joint progressions. We study several {JPM} variants (Pairwise, Bradley–Terry, Plackett–Luce, and Mallows) and analyze three properties: (i) calibration–whether lower model energy predicts smaller distance to the ground truth ordering; (ii) separation–the degree to which sampled rankings are distinguishable from random permutations; and (iii) sharpness–the stability of sampled aggregate rankings. All variants are calibrated, and all achieve near-perfect separation; sharpness varies by variant and is well-predicted by simple features of the input partial rankings (number and length of rankings, conflict, and overlap). In synthetic experiments, {JPM} improves ordering accuracy by roughly 21% over a strong {EBM} baseline ({SA}-{EBM}) that treats the joint disease as a single condition. Finally, using {NACC}, we find that the Mallows variant of {JPM} and the baseline model ({SA}-{EBM}) have results that are more consistent with prior literature on the possible disease progression of the mixed pathology of {AD} and {VaD}.