Diagnostic Value of Hematological Inflammatory Ratios in Brucellosis

Background/Objectives: This study aimed to evaluate the diagnostic utility of mean platelet volume (MPV) and hematological inflammatory ratios (NLR, PLR, LMR) in brucellosis, and to develop a combined diagnostic model integrating these parameters with ESR and CRP for cost-effective diagnosis in endemic areas. Methods: This retrospective case-control study included 50 patients with confirmed brucellosis and 50 age-matched healthy controls at Balıkesir University Hospital (2015-2018). Brucellosis was confirmed by positive blood culture or Standard Agglutination Test ≥1/160 with compatible symptoms. CBC parameters, ESR, and CRP were measured at diagnosis. MPV, NLR, PLR, and LMR were calculated and compared between groups. ROC curve analysis evaluated diagnostic performance, and multivariate logistic regression developed a combined diagnostic model. Results: Brucellosis patients showed significantly lower MPV (8.04±0.95 vs 8.56±0.69 fL, p=0.002) and NLR (median: 1.69 vs 2.07, p=0.013), higher platelet counts (305.0±116.0 vs 246.0±55.2 ×10³/μL, p=0.002) and LMR (median: 5.28 vs 4.12, p=0.008), while PLR showed no difference. ESR and CRP were elevated (both p< 0.001). ROC analysis showed ESR had the best individual performance (AUC=0.842), followed by CRP (AUC=0.724), MPV (AUC=0.697), LMR (AUC=0.681), and NLR (AUC=0.644). The combined model (MPV+ESR+CRP) achieved superior performance (AUC=0.891) with 84% sensitivity and 86% specificity. Focal complications showed lower MPV (p=0.038). Conclusions: Brucellosis presents a unique hematological profile with decreased MPV and NLR but elevated LMR. The combined MPV+ESR+CRP model demonstrated excellent diagnostic accuracy, offering a cost-effective approach for early diagnosis in resource-limited endemic settings, with lower MPV associated with complicated disease and prognostic value.