Objective To study the predictive value of the baseline neutrophil/lymphocyte to platelet ratio (N/LP) and neutrophil/lymphocyte ratio (NLR) in the condition and prognosis of adult-onset Still's disease (AOSD).

Methods A total of 110 AOSD patients were retrospectively analyzed. The baseline characteristics between non-refractory AOSD patients (n = 68) and refractory AOSD patients (n = 42) were compared, and the optimal threshold of NLR and N/LP were calculated by ROC curve.

Results The proportion of splenomegaly in refractory AOSD patients was 47.62%, which was higher than that in non-refractory AOSD patients (23.53%) (P ＜ 0.01). Compared with the non-refractory AOSD patients, the lymphocyte and platelet counts in refractory AOSD patients were lower, while the lactate dehydrogenase, AOSD system score, serum ferritin and C-reactive protein were significantly higher (P ＜ 0.05 to P ＜ 0.01). The areas under the curves of N/LP and NLR for predicting the severity of patients' conditions were 0.721 and 0.654, respectively, the optimal cut-off values were 0.028 and 10.555, their sensitivities were 78.60% and 52.40%, and their specificities were 65.70% and 74.60%. When N/LP ＞ 0.028 and/or NLR ＞ 10.555, patients with refractory AOSD could be determined.

Conclusions Baseline N/LP and NLR levels have high value in predicting the occurrence of refractory AOSD, and are worthy of promoting in clinic practice.