Renal impairment and prognosis in mannitol-treated intracerebral hemorrhage: a retrospective clinical analysis.

BACKGROUND

Mannitol is commonly used to control intracranial hypertension in intracerebral hemorrhage (ICH), yet its renal safety and impact on clinical outcomes remain uncertain.

OBJECTIVE

To evaluate the association between mannitol exposure, acute kidney injury (AKI), and in-hospital mortality in adults with spontaneous ICH.

METHODS

We performed a retrospective cohort study using MIMIC-IV. Patients were grouped by receipt of mannitol during the ICU stay. To address confounding, we used propensity score matching (PSM) and inverse-probability-of-treatment weighting (IPTW) with balance diagnostics. Primary outcomes were AKI (KDIGO criteria) and in-hospital mortality. Prespecified subgroup analyses included baseline Glasgow Coma Scale (GCS), and time-to-event analyses used Cox models. Because direct invasive intracranial pressure (ICP) data were available in only a minority of patients (≈29%), invasive ICP trajectories were presented descriptively for this subset without imputation and were not incorporated into adjusted outcome models.

RESULTS

Of 2,421 eligible patients, 398 received mannitol. After PSM, mannitol use was associated with higher in-hospital mortality (48.7 % vs 22.0 %; p < 0.001) and AKI (38.7 % vs 22.9 %; p < 0.001). In patients with GCS ≤ 8, mortality remained higher in the mannitol group. IPTW analyses demonstrated directionally consistent associations with satisfactory post-weighting covariate balance. In the invasive-ICP subset, elevated first ICP was more common among mannitol recipients (descriptive analysis), consistent with confounding by indication.

CONCLUSIONS

In this large, real-world ICH cohort, mannitol exposure was associated with increased risks of AKI and in-hospital mortality, particularly among patients with severe neurological impairment. Given substantial missingness of invasive ICP and the observational design, residual confounding cannot be excluded. These findings support judicious, indication-driven use of mannitol with proactive renal monitoring, and underscore the need for prospective studies with standardized ICP monitoring and detailed exposure profiling.