Acute-Phase Plasma Osteopontin as an Independent Predictor for Poor Outcome After Aneurysmal Subarachnoid Hemorrhage

Experimental studies reported that osteopontin (OPN), a matricellular protein, is induced in brain after subarachnoid hemorrhage (SAH). The aim of this study was to investigate the relationships between plasma OPN levels and outcome after aneurysmal SAH in a clinical setting. This is a prospective study consisting of 109 aneurysmal SAH patients who underwent aneurysmal obliteration within 48 h of SAH. Plasma OPN concentrations were serially determined at days 1–3, 4–6, 7–9, and 10–12 after onset. Various clinical factors as well as OPN values were compared between patients with 90-day good and poor outcomes. Plasma OPN levels were significantly higher in SAH patients compared with control patients and peaked at days 4–6. Poor-outcome patients had significantly higher plasma OPN levels through all sampling points. Receiver-operating characteristic curves demonstrated that OPN levels at days 10–12 were the most useful predictor of poor outcome at cutoff values of 915.9 pmol/L (sensitivity, 0.694; specificity, 0.845). Multivariate analyses using the significant variables identified by day 3 showed that plasma OPN ≥ 955.1 pmol/L at days 1–3 (odds ratio, 10.336; 95% confidence interval, 2.563–56.077; p < 0.001) was an independent predictor of poor outcome, in addition to increasing age, preoperative World Federation of Neurological Surgeons grades IV–V, and modified Fisher grade 4. Post hoc analyses revealed no correlation between OPN levels and serum levels of C-reactive protein, a non-specific inflammatory parameter, at days 1–3. Acute-phase plasma OPN could be used as a useful prognostic biomarker in SAH.