Fisher-Rao distance and sex differences in disease prevalence trajectories
Abstract
Objectives
We introduce a new application of the Fisher–Rao geodesic distance to quantify sex differences in age-stratified chronic-disease prevalence trajectories, modelling those trajectories as dynami-cal systems on the hyperbolic plane and using GBD 2021 data.
Methods
We analysed prevalence for 10 major chronic conditions across three regions—US states (50 states + DC), 24 Western European countries, and 47 Japanese prefectures—over 1990–2019. We logit-transformed prevalence and summarised each age-sex cohort by normal-approximation parameters ( µ, σ ), which were then embedded in the hyperbolic plane. Sex differences were quantified as the difference between the total Fisher–Rao trajectory lengths for males and females. We assessed cross-regional consistency using parametric (mean differences) and nonparametric (Cohen’s g) summaries, and compared Fisher–Rao results to KL divergence, absolute mean differences, and absolute SD differences.
Study design
Cross-sectional analysis of GBD 2021 prevalence data modelled as trajectories in the hyperbolic plane.
Results
The Fisher–Rao distance showed greater cross-regional consistency than the alternative metrics. Males showed greater trajectory shifts in neoplasms, cardiovascular diseases, chronic respiratory diseases, diabetes/kidney diseases, skin/subcutaneous diseases, and sense organ diseases. Females showed greater shifts in neurological disorders, mental disorders, and substance use disorders. Digestive diseases exhibited mixed patterns.
Conclusions
This geometry-informed metric outperforms alternatives in assessing sex disparities in disease burdens, enhancing public health surveillance and equity in chronic disease management. Future extensions should incorporate gender dimensions.
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