Association between initial intravenous fluid volume and the composite outcome of hemodialysis dependence at discharge or in-hospital mortality in inpatients with rhabdomyolysis.

Background: Although experts recommend intravenous fluid (IVF) for patients with rhabdomyolysis to prevent renal injury, the optimal IVF volume remains unknown because excessive IVF may lead to organ edema, resulting in organ injury. This study aimed to investigate the association between IVF volume and the composite outcome of hemodialysis dependence or in-hospital death in patients with rhabdomyolysis.

Methods: We retrospectively identified patients with rhabdomyolysis admitted to intensive care units and tertiary-care hospitals from July 2010 to March 2022 using the Japanese Diagnosis Procedure Combination database. We divided the patients into those who received at least 3500 mL/day of IVF within 3 days of admission and those who did not. This threshold was defined based on the findings of previous studies. We compared the composite outcome, including hemodialysis dependence at discharge and in-hospital death, between the groups using propensity score overlap weighting.

Results: We identified 5392 eligible patients. Of those, 1677 (31.1%) received ≥ 3500 mL/day of IVF, and 3715 (68.9%) received < 3500 mL/day of IVF; the total volumes of IVF within 3 days of admission were 11,039 mL and 4054 mL, respectively. Propensity-score overlap weighting created balanced cohorts, which did not show significant difference in primary composite outcome between the groups (3.4% vs. 3.9%; risk difference [RD] - 0.4, 95% confidence interval [CI] - 1.8 to 0.9, P = 0.53). The proportion of hemodialysis dependence was lower in the IVF ≥ 3500 mL/day group than those in the < 3500 mL/day group (0.4% vs. 1.3%; RD - 0.9, 95% CI - 1.6 to - 0.2, P = 0.02).

Conclusions: This retrospective database study found that IVF ≥ 3500 mL/day for patients with rhabdomyolysis was not associated with a reduction in the composite outcome but was associated with a reduction in hemodialysis dependence at discharge. The optimal IVF volume still remains unknown, and further studies are warranted.