Clinical utility of neutrophil-lymphocyte ratio in the diagnosis of neuroleptic malignant syndrome.

Background: Neuroleptic malignant syndrome (NMS) is a life-threatening side effect of antipsychotic medication. In this study, we aimed to investigate the hypothesis of inflammation via neutrophil-lymphocyte ratio (NLR) in the etiology of NMS. Methods: In this retrospective case-control study, data were collected using digital database of Bakırköy Mental Health Research and Training State Hospital by screening NMS diagnosis according to 'International Classification of Diseases (ICD-10) code: G21.0' between the years of 2007 and 2017. We included 32 hospitalizations with the diagnosis of NMS and 31 other acute psychiatric hospitalizations without NMS of same patients. NLR was calculated as proportion of absolute neutrophil count to absolute lymphocyte count. Significance level was accepted as p < .05. Results: The mean NLR value of NMS group was 9.55 ± 5.13 and control group was 2.06 ± 0.71 (p < .001). According to ROC analysis in our study group, we found a mean NLR cutoff value ≥4 and lymphocyte percent cutoff of ≤18.4% have the probability of correctly identifying patients with NMS with the 100% sensitivity and 100% specificity. Conclusions: In this retrospective study, we considered that higher NLR value in NMS episode might be a resemblance of systemic inflammatory state. In addition, our results suggest that both NLR and lymphocyte percentage may be alternative minor criteria which are more sensitive and specific than leukocyte levels and CPK.