Renal survival and improvement in younger malignant hypertension patients with thrombotic microangiopathy

Hypertension (HTN) is increasing among young people. Notably, younger individuals are more susceptible to malignant hypertension (MHT). The occurrence and renal prognosis in MHT patients with thrombotic microangiopathy (TMA) across different age groups remains undetermined. This prospective cohort study evaluated 292 MHT patients with TMA in China from 2008 to 2023. We examined the clinical and pathological characteristics according to median age categories (≤35 years and >35 years). The associations of age with renal outcomes were examined in Cox regression models. The primary outcome was long-term renal replacement therapy (RRT). The secondary outcome was an increase of at least 15% in estimated glomerular filtration rate (eGFR). Among 292 patients, individuals younger than 35 years had significantly higher proteinuria, proportion of patients with immunoglobulin A nephropathy (IgAN), and global sclerosis ratio compared to those older than 35 years. Age ≤35 years was associated with a worse outcome of long-term RRT outcome (Hazard ratios [HRs]: 1.60 [95% confidence interval [CI]: 1.06-2.40]) and better improvement of ≥15% increase in eGFR (HRs: 1.93 [95% CI: 1.20-3.11]). Serum creatinine >565 μmol/L and proteinuria >1.41 g/d were associated with a higher risk of long-term RRT, while serum albumin >35 g/L was correlated with a lower risk of it. Tubular atrophy/interstitial fibrosis >50% was an unfavorable factor for ≥15% increase in eGFR. In conclusion, young age contributed to a better renal improvement of ≥15% increase in eGFR, especially within 6 years. However, a worse outcome of long-term RRT also occurred in the younger MHT patients with TMA.