Abstract
Objectives This study aimed to identify the utility of peripheral neutrophil-to-lymphocyte ratio (NLR), neutrophil-to-monocyte ratio (NMR), monocyte-to-lymphocyte ratio (MLR), platelet-to-lymphocyte ratio (PLR), systemic inflammatory index (SII), systemic inflammatory response index (SIRI) and blood lactate in differentiating between SE and FS.
Methods Retrospective case control study in adults presenting to a tertiary hospital (Alfred Health) between 2017 and 2020. SE was defined as per ILAE criteria for time point 1. FS events needed to meet the same time criterion. Bloods were obtained during the event or within 12 hours of offset.
Results After screening 1262 cases, 79 SE events from 66 patients and 44 prolonged PNES events from 28 patients were analysed. NLR, NMR, MLR, PLR, SII, SIRI and lactate levels were higher in SE compared with FS. Using ROC curves and Youden’s index, cut-off values were identified with sensitivities between 0.38 to 0.84, specificities between 0.64 and 1.00 and AUCs between 0.62 to 0.79. Lactate levels peaked at 60 minutes whereas cell ratios mostly peaked between 240 to 360 minutes post onset. Two nomogram prediction models combining lactate and either SII or SIRI were generated. Using ROC curves, AUCs of 0.92 and 0.90, sensitivities of 0.81 and 0.79 and specificities of 1.0 and 0.95 were identified where the cut-off probability of SE was >0.79 and >0.80 respectively.
Conclusion Combining early peaking lactate and later peaking SII or SIRI resulted in prediction models with good sensitivity and specificity for distinguishing SE from FS. If validated, this can have important diagnostic implications.
