High serum substance P levels and mortality after malignant middle cerebral artery infarction.

Purpose: Previously our team found higher serum substance P concentrations at day 1 of a malignant middle cerebral artery infarction (MMCAI) in non-surviving than in surviving patients. Thus, the objective of this study was to determine whether serum substance P levels during the first week of MMCAI could predict mortality.

Methods: We included patients with MMCAI defined as computed tomography findings of acute infarction in at least of 50% of the territory and Glasgow Coma Scale ≤8. We determined serum concentrations of substance P on days 1, 4 and 8 of MMCAI. Thirty-day mortality was the study end-point.

Results: Serum substance P concentrations at days 1 (p < .001), 4 (p < .001), and 8 (p = .001) of MMCAI in non-surviving (n = 34) were higher than in surviving patients (n = 34). Receiver operating characteristic analyses showed that serum substance P concentrations at days 1, 4, and 8 of MMCAI had an area under curve (95% confidence intervals) to predict 30-day mortality of 0.77 (0.66-0.87; p < .001), 0.82 (0.69-0.91; p < .001) and 0.85 (0.72-0.94; p < .001) respectively.

Conclusions: The two new findings of our study are that non-surviving MMCAI patients showed higher serum substance P levels at day 1, 4 and 8 than surviving, and that those levels could predict 30-day mortality.