Early 72-h serum creatinine kinetics predict 90-day mortality in hepatorenal syndrome-associated AKI.

Hepatorenal syndrome-associated acute kidney injury (HRS-AKI) carries high short-term mortality. Prognosis is usually based on creatinine-defined AKI stage, but early creatinine trajectories may add information. In this retrospective cohort study (January 2019-September 2024), we included adults with cirrhosis fulfilling contemporary ADQI/ICA-based criteria for HRS-AKI. Using a prespecified 72-h landmark approach, excluding patients who died within the first 72h, we classified serum creatinine kinetics over the first 72 h after diagnosis as increasing or decreasing and evaluated associations with 90-day all-cause mortality after diagnosis. Landmark Cox models adjusted for age, sex, baseline creatinine, Child-Pugh class, and platelet count and tested interaction with AKI stage. Seventy-five patients comprised the landmark cohort (rising n = 36; falling n = 39). Ninety-day survival differed by kinetics (log-rank p = 0.0018). Rising creatinine independently predicted mortality (adjusted hazard ratio 2.24, 95% CI 1.20-4.18; p = 0.011) alongside Child-Pugh class (hazard ratio per class 3.99, 95% CI 1.67-9.52; p = 0.002). There was no evidence of effect modification by AKI stage (interaction p = 0.27). Renal replacement therapy occurred more often with rising creatinine (36.1 vs. 10.3%; p = 0.012). Early 72-h creatinine kinetics provides prognostic information beyond conventional AKI stage in HRS-AKI; an increasing trajectory identifies patients at high risk of death and dialysis and may support early risk stratification.