Lorente L, Martín MM, Pérez-Cejas A, et al. - Given higher serum substance P levels at day 1 of a malignant middle cerebral artery infarction (MMCAI) have been previously reported in non-surviving vs surviving patients, therefore, researchers investigated if mortality could be predicted by serum substance P levels during the first week of MMCAI. The endpoint of the study was thirty-day mortality. For the prediction of 30-day mortality, an area under the curve of 0.77, 0.82 and 0.85 was yielded by serum substance P concentrations at days 1, 4, and 8 of MMCAI, respectively, as shown in receiver operating characteristic analyses. This work affords two novel findings: higher serum substance P levels were detected at day 1, 4 and 8 in non-surviving MMCAI patients vs surviving, and those levels served as a predictor of 30-day mortality.