Inflammatory Biomarkers and Psychiatric Symptoms in Patients with Brucellosis: Associations with the Platelet-to-Lymphocyte Ratio

Brucellosis, a multisystemic zoonotic infection, is increasingly recognized not only for its burden but also for its psychiatric complications. The aim of the present study was to evaluate depression and anxiety levels in patients with brucellosis and to determine if the platelet-to-lymphocyte ratio (PLR) is associated with psychiatric symptom severity. A comparative cross-sectional study was conducted, including 110 patients with brucellosis with symptom durations ≥8 weeks and 80 healthy comparison participants. Depression and anxiety were evaluated using the Beck Depression Inventory (BDI) and the Beck Anxiety Inventory (BAI). Inflammatory indices derived from complete blood counts were calculated, with the PLR as the primary index of interest. Multivariate covariance analysis and multivariable linear regression analyses were performed to examine associations between the PLR and psychiatric symptoms. Clinically depressive symptoms were observed in 41% of patients versus 11% of participants in the healthy comparison group, and clinically significant anxiety symptoms were observed in 42% and 9%, respectively. Platelet-to-lymphocyte ratio values were significantly higher in brucellosis patients compared with the healthy comparison group (129.94 ± 44.94 versus 98.79 ± 8.02; P <0.001). The PLR exhibited significant positive correlations with both BDI (ρ = 0.303; P = 0.001) and BAI scores (ρ = 0.279; P = 0.003). In multivariable linear regression analyses, the PLR was independently associated with both depression (β = 0.202; P = 0.001) and anxiety scores (β = 0.357; P = 0.002) after adjustment for age, sex, education level, and other inflammatory indices. The PLR may represent a cost-effective laboratory marker associated with psychiatric symptom severity in patients with brucellosis. These findings suggest that the PLR warrants further investigation as a potential screening adjunct in resource-limited endemic settings, although validation in independent cohorts is needed.