Neutrophil-lymphocyte ratio and platelet-lymphocyte ratio are 2 new inflammatory markers associated with pulmonary involvement and disease activity in patients with dermatomyositis.

BACKGROUND

The neutrophil-lymphocyte ratio (NLR) and platelet-lymphocyte ratio (PLR) have emerged as useful biomarkers to predict systemic inflammation. However, there is no study to investigate the relationship between the biomarkers and dermatomyositis (DM).

METHODS

Seventy-three newly diagnosed patients with DM and 147 healthy subjects were selected in this retrospective study. We divided the 73 DM patients into 2 groups: 55 without interstitial lung disease (ILD) and 18 with ILD. Complete clinical characteristics were extracted from the medical records of DM patients. The correlations between NLR, PLR, the clinical characteristics and the disease activity were analyzed.

RESULTS

For DM patients without ILD, the NLR and PLR were significantly higher than those in the control group (both P<0.001). For DM patients with ILD, the NLR and PLR were higher than in DM patients without ILD (P=0.004 and P=0.026, respectively). The NLR was positively correlated with C-reactive protein (CRP) (r=0.543, P<0.001) and the erythrocyte sedimentation rate (ESR) (r=0.513, P=0.001). The global activity scores correlated positively and significantly with NLR, PLR, and CRP (r=0.486, P<0.001; r=0.240, P=0.041; and r=0.343, P=0.003, respectively). Based on the ROC curve, to predict DM patients with ILD, the best cut-off value of the NLR was 3.98 (sensitivity 88.9%, specificity 52.7%, AUC=0.727), and the best cutoff value of PLR was 221.69 (sensitivity 77.8%, specificity 69.1%, AUC=0.722).

CONCLUSIONS

Both NLR and PLR exhibit favorable diagnostic performance in predicting pulmonary involvement and disease activity in patients with DM. We provide the optimal cut-off values for DM patients with ILD that would maximize the diagnostic efficiency.