Introduction: Soluble ST2 (sST2) is a member of the Toll-like receptor superfamily implicated in pro-inflammatory signaling. We investigated whether sST2 predicts delayed cerebral ischemia (DCI) and 90-day clinical outcome in patients with aneurysmal subarachnoid hemorrhage (SAH).
Methods: Soluble ST2 was measured in plasma samples from 182 patients who presented to a single institution with SAH. Blood samples were collected between days 1 and 5 after onset of SAH, and prior to the onset of DCI. Functional outcome was assessed at 3 months using the modified Rankin Scale (mRS) with good and poor outcome defined as mRS 0-2 and 3-6, respectively. Using a consensus definition, DCI was defined as a 2-point drop in GCS over a sustained period in patients whose clinical deterioration could not be explained by another cause. The relationships between sST2 level, DCI and outcome were assessed in univariable analysis. Multivariable logistic regression, Kaplan-Meier survival analysis, and receiver operating characteristic curves were used to determine the ability of sST2 to predict outcome and mortality. These findings were tested for replication in an independent cohort of 51 SAH patients recruited from a separate institution.
Results: The discovery cohort consisted of 182 subjects (mean age 56±12 years, 61% women). Elevated plasma sST2 predicted the development of DCI (OR 2.10, 95% 1.06-4.18 CI, P=0.0295), which remained an independent predictor after adjustment for age, World Federation of Neurological Surgeons (WFNS) grading score, modified Fisher score, intra-arterial vasodilator therapy and hydrocephalus (OR 2.78, 95% CI 1.00-7.97, p=0.0453). Elevated sST2 was also independently associated with poor 90-day functional outcome (OR 2.65, 95%CI 1.07-6.59, P=0.0304), and mortality (OR 5.36, 95% CI 1.48-19.39, p=0.0039) when adjusted for age, WFNS score, modified Fisher score and hydrocephalus. In the replication cohort (N=51, 88% women), sST2 level was an independent predictor of DCI (OR 5.02, 95% CI 1.46-17.20, p=0.0034) and outcome at 90 days (OR 4.24, 95% CI 1.31-13.74, p=0.0072).
Conclusion: Plasma sST2 level predicted risk of DCI, outcome, and mortality after SAH. Further study of the potential link between sST2 and brain injury after SAH is warranted.