RESUMO
Abstract Background: Granulomatosis with polyangiitis (GPA) is a granulomatous necrotizing vasculitis with high morbidity and mortality. Anti-neutrophil cytoplasmic antibody is a valuable diagnostic marker, however its titer lacks predictive value for the severity of organ involvement. Platelet to lymphocyte ratio (PLR) and mean platelet volume (MPV) has been regarded as a potential marker in assessing systemic inflammation. We aimed to explore the value of PLR and MPV in the assessment of disease activity and manifestations of disease in GPA. Methods: 56 newly diagnosed GPA patients and 53 age-sex matched healthy controls were included in this retrospective and cross-sectional study with comparative group. Complete blood count was performed with Backman Coulter automatic analyzer, erythrocyte sedimentation rate (ESR) with Westergen method and C-reactive protein (CRP) levels with nephelometry. The PLR was calculated as the ratio of platelet and lymphocyte counts. Result: Compared to control group, ESR, CRP and PLR were significantly higher and MPV significantly lower in GPA patients. In patients group, PLR was positively correlated with ESR and CRP (r = 0.39, p = 0.005 and r = 0.51, p < 0.001, respectively). MPV was negatively correlated with ESR and CRP (r = - 0.31, p = 0.028 and r = - 0.34 p = 0.014, respectively). Patients with renal involvement had significantly higher PLR than patients without renal involvement (median:265.98, IQR:208.79 vs median:180.34 IQR:129.37, p = 0.02). PLR was negatively correlated with glomerular filtration rate (r = - 0.27, p = 0.009). A cut-off level of 204 for PLR had 65.6% sensitivity and 62.5 specificity to predict renal involvement. Conclusion: PLR exhibit favorable diagnostic performance in predicting renal involvement in patients with GPA.(AU)