To evaluate the associations of inflammatory factors and serological test results with complicated
brucellosis, we recruited 285 patients with a diagnosis of
brucellosis between May 2016 and September 2019. The patients were subsequently classified into two groups according to the presence of complications. We collected demographic and clinical information and routine laboratory test results in addition to anti-Brucella
IgG and
IgM levels. Anti-Brucella
IgG and
IgM were uniformly tested using
enzyme-linked
immunosorbent assays (ELISAs) in this study. Among the 285 patients with
brucellosis, 111 (38.95%) had complicated
brucellosis.
Osteoarthritis occurred more often in the subacute and chronic stages than in the acute stage (P = 0.002). Genital
infection occurred more frequently in the acute stage than in the other stages (P = 0.023).
Fever was not frequently observed in complicated cases (P < 0.001). The erythrocyte sedimentation rate (ESR) and the
C-reactive protein (CRP) and anti-Brucella
IgM and
IgG levels were higher in complicated-
brucellosis patients than in uncomplicated-
brucellosis patients (P < 0.001). Anti-Brucella
IgG, with an area under the curve of 0.885 (95% confidence interval [CI], 0.847 to 0.924), was the most robust
indicator of complicated
brucellosis. Positive culture, anti-Brucella
IgM, the ESR, and CRP could be considered indicators, but their efficacy was weaker than that of
IgG. In conclusion, a high ESR, high CRP, high anti-Brucella
IgM and
IgG levels, and positive culture were indicators of complicated
brucellosis; among these, anti-Brucella
IgG was the most robust
biomarker.