Timing of Renal Replacement Therapy in Burn Patients With Acute Kidney Injury: A Retrospective Cohort Study.

Introduction: Acute kidney injury (AKI) is common in severe burns with high mortality. Previous studies confirmed the renal replacement therapy (RRT) as an effective strategy in burn patients. However, the optimal timing of RRT initiation with AKI is rarely investigated.

Methods: We conducted a single-center, retrospective cohort study at a large burn center in Chongqing, China, from 2010 to 2020. Patients were grouped into early (initiated at Kidney Disease: Improving Global Outcomes stage 1 or 2 of AKI) and delayed RRT (initiated at Kidney Disease: Improving Global Outcomes stage 3 of AKI). The primary outcome was in-hospital mortality. The secondary outcomes included renal function recovery, length of stay, and RRT-related complications.

Results: Of the included 79 patients, 42 and 37 were in early and delayed RRT group, respectively. The mean burn area was 68.82%. The in-hospital mortality tended to be higher in the early group (42.86%) than in the delayed group (29.73%, P = 0.227), although the difference was not statistically significant. The rate of partial remission of renal function at 48 hours after RRT discontinuation was significantly higher in the delayed group (78.26%) than early group (36.84%, P = 0.003). Furthermore, multivariable Cox and logistic regression analysis found that interval from AKI occurrence to RRT initiation was protective factors for 90-day mortality (hazard ratio 0.514, 95% confidence interval 0.349-0.756, P = 0.001), but fluid overload, acute respiratory distress syndrome, and multiple organ dysfunction syndrome were risk factors for mortality. Subgroup analysis revealed that patients with stage 1 or 2 AKI who received RRT within 24 hours after AKI had the lowest survival rate. In contrast, patients with stage 3 AKI who received RRT beyond 24 hours after AKI had the highest survival rate. The delayed group had higher rate of bleeding and lower rate of catheter-related infection than the early group.

Conclusions: Delayed initiation of RRT seemed to have similar survival benefits to early RRT initiation in burn patients with AKI, needing further confirmation by large randomized clinical study in future.