Neutrophil-to-lymphocyte ratio (NLR) as a severity predictor of leprosy reaction

Background: Leprosy can lead to progressive disability by leprosy reactions. There is no gold standard to diagnose leprosy reactions nor guidance to determine patients' risk of leprosy reactions. This study aims to study the diagnostic value and accuracy of neutrophil-to-lymphocyte ratio (NLR) on leprosy reactions.

Methods: A retrospective cross-sectional study was conducted by Prof. dr. I, Goesti Ngoerah Gde Ngoerah General Hospital used secondary data from January 2018 to December 2021 from patients diagnosed with leprosy with/without leprosy reaction. The neutrophil-to-lymphocyte ratio was calculated for all patients, and a receiver operating characteristic curve (ROC) was generated to identify the NLR cut-off point. The Chi-square/Fisher exact test was performed to determine the risk ratio.

Results: The NLR cut-off point to reversal reaction (RR) was 2.81 (sensitivity: 73.7% and specificity: 74.2%), while the NLR cut-point to erythema nodosum leprosum (ENL) was 3.97 (sensitivity: 93.8% and specificity: 91.4%). A high NLR value showed a significantly increased risk to RR and ENL. The correlation test between NLR and severe RR (r:0.389; p<0.001) and severe ENL (r:0.394; p<0.001) both showed a significant result.

Conclusion: Increased risk of RR and ENL in leprosy patients who had high NLR. High NLR was weakly positively correlated to severe RR and ENL reactions of leprosy patients at Prof. dr. I Goesti Ngoerah Gde Ngoerah General Hospital.