ABSTRACT
INTRODUCTION: Leprosy reactions, classified as type 1 and type 2 reactions, are acute clinical conditions of exacerbation of localized or systemic inflammatory response inpatients with leprosy. No laboratory biomarker is available to predict the emergence of these reactions. Neutrophil-to-lymphocyte ratio (NLR) is an accurate biomarker for diagnosis and prognosis of various inflammatory and neoplastic diseases. OBJECTIVE: This study aimed to investigate the accuracy of the NLR in the diagnosis of leprosy reactions. MATERIALS AND METHODS: NLR was calculated for all patients and a receiver operating characteristic curve (ROC) were generated to identify the NLR cut-off point. RESULTS: A total of 123 patients with leprosy were included, 98 with leprosy reactions of which 56 (45.5%) had type 1 and 42 (34.1%) with type 2. Mean NLR was higher among patients with reactions than among those without. It was also statistically higher among patients with type 2 reactions than in those with type 1 reactions. Receiver operating characteristic curves were generated to identify the NLR cut-off point. The area under the ROC curve was 0.794 for diagnosis of any leprosy reaction and 0.796 for the diagnosis of type 2 reaction. The NLR cut-off points for diagnosis of any leprosy reaction and for type 2 reaction were 2.75 (sensitivity 61.0%, specificity 92.0%, accuracy 77.0%) and 2.95 (sensitivity 81.0%, specificity 74.0%, accuracy 78.0%), respectively. CONCLUSION: These results suggest that NLR could be a potential biomarker for diagnosis of leprosy reaction and useful for discriminating patients with type 2 reactions from those with type 1 leprosy reactions.