Delta neutrophil index contributes to the differential diagnosis between acute gout attack and cellulitis within 24 hours after hospitalization.

Objective: An acute gout attack is often misdiagnosed as cellulitis. Differentiating these two diseases is crucial when deciding treatment strategies. Delta neutrophil index (DNI) represents the difference between leucocyte subfractions that corresponds to the fraction of immature granulocytes and can predict the bacterial infection burden. The aim of this study was to evaluate the potential of DNI as a predictive marker for differentiating an acute gout attack and cellulitis.
Methods: We reviewed medical records of 184 patients with an acute gout attack and 183 patients with lower limb cellulitis. DNI was automatically determined by the ADVIA 2120 electronic cell analyser. We used logistic regression to determine independent variables for predicting cellulitis among clinical and laboratory markers. We performed a subgroup analysis among patients without MSU crystal confirmation and among patients with normouricaemia.
Results: Patients with an acute gout attack had lower values of DNI than those with cellulitis (0.6 vs 2.8%; P < 0.001). These results were consistent in patients without MSU confirmation and in patients with normouricaemia (0.5 vs 2.8 and 0.7 vs 2.6%, respectively; P < 0.001 for both). A cut-off value of 1.7% was determined to predict cellulitis. Multivariate analysis showed that DNI was the only independent predictive value for cellulitis (odds ratio 9.699). Similar results were found in patients without MSU confirmation and in patients with normouricaemia (odds ratio 18.763 and 5.215, respectively).
Conclusion: This study showed that DNI was an effective independent marker to differentiate between an acute gout attack and cellulitis at the crucial early phase irrespective of MSU crystal confirmation or serum uric acid concentration.