Dose-response association between admission neutrophil-to-lymphocyte ratio and clinical severity in Gloydius brevicaudus envenomation.

BACKGROUND

Snakebite envenomation triggers a complex systemic inflammatory response; however, the immunological features underlying clinical severity remain incompletely characterized. The NLR reflects the balance between innate immune activation and adaptive immune suppression, yet its association with clinical severity in Gloydius brevicaudus envenomation has not been systematically evaluated.

METHODS

We performed a retrospective cohort study of 203 patients with confirmed G. brevicaudus envenomation. Clinical severity at presentation was assessed using a simplified bedside severity score based exclusively on clinical manifestations and dichotomized as mild or moderate-to-severe. Admission NLR was evaluated as a marker of inflammatory phenotype. Multivariable logistic regression models were constructed adjusting for demographic and bite-related factors. Dose-response relationships were explored using log-transformed NLR and quartile-based analyses with trend testing.

RESULTS

Patients with moderate-to-severe envenomation exhibited significantly higher admission NLR values. After adjustment for baseline clinical characteristics, log-transformed NLR remained independently associated with inflammatory severity (adjusted odds ratio [OR] 1.98, 95% confidence interval [CI] 1.39-2.81). This association persisted after additional adjustment for infection status and leukocytosis. Quartile analyses demonstrated a clear dose-response relationship, with patients in the highest NLR quartile showing a nearly fourfold increased risk of moderate-to-severe envenomation compared with those in the lowest quartile (adjusted OR 3.94, 95% CI 1.69-9.17; P for trend < 0.001).

CONCLUSION

Elevated admission NLR is strongly associated with inflammatory severity in G. brevicaudus envenomation and exhibits a robust dose-response relationship. These findings support NLR as a readily available marker reflecting envenomation-associated immune dysregulation and highlight the contribution of neutrophil-lymphocyte imbalance to severe inflammatory phenotypes following snakebite.