Dynamic haematuria trajectories uncover a high-risk phenotype in IgA nephropathy

Abstract Background Haematuria is a common yet non-specific clinical manifestation of IgA nephropathy (IgAN), and its prognostic value remains controversial. We aimed to identify distinct longitudinal haematuria trajectories and evaluate their independent prognostic value for renal outcomes in patients with IgA nephropathy. Methods A retrospective analysis was conducted on 388 patients with IgAN who underwent at least five dipstick-based haematuria assessments. Latent class trajectory modelling was applied to identify distinct patterns of haematuria evolution. Associations between trajectory classes and the composite renal outcome were evaluated using multivariable logistic regression. Sensitivity analyses included lagged analysis excluding the first follow-up measurement, validation in a proteinuria-enriched subgroup, and re-estimation of trajectory models in a contemporary cohort restricted to patients diagnosed in 2015 or later. Results Three haematuria trajectories were identified: trajectory 1 (moderate levels declining to low), trajectory 2 (high baseline levels declining to moderate), and trajectory 3 (initial decline followed by rebound). Trajectory 3 exhibited a higher risk of adverse renal outcomes and a poorer than those in trajectory 1. This group also demonstrated a higher prevalence of severe histopathological features and reduced use of angiotensin-converting enzyme inhibitors. The prognostic significance of trajectory 3 was particularly pronounced in younger, normotensive patients with preserved renal function. Conclusion Dynamic haematuria trajectories provide prognostic information beyond baseline measurements. A trajectory characterized by elevated baseline levels of haematuria levels, early decline, and subsequent rebound identified a high-risk subgroup, underscoring the importance of incorporating longitudinal urinary data into risk stratification and clinical decision-making.