title: Serum procalcitonin for differentiating bacterial infection from disease flares in patients with autoimmune diseases.
abstract: Early differentiation between bacterial infections and disease flares in autoimmune disease patients is important due to different treatments. Seventy-nine autoimmune disease patients with symptoms suggestive of infections or disease flares were collected by retrospective chart review. The patients were later classified into two groups, disease flare and infection. C-reactive protein (CRP) and serum procalcitonin (PCT) levels were measured. The CRP and PCT levels were higher in the infection group than the disease flare group (CRP,11.96 mg/dL ± 9.60 vs 6.42 mg/dL ± 7.01, P = 0.003; PCT, 2.44 ng/mL ± 6.55 vs 0.09 ng/mL ± 0.09, P < 0.001). The area under the ROC curve (AUC; 95% confidence interval) for CRP and PCT was 0.70 (0.58-0.82) and 0.84 (0.75-0.93), which showed a significant difference (P < 0.05). The predicted AUC for the CRP and PCT levels combined was 0.83, which was not significantly different compared to the PCT level alone (P = 0.80). The best cut-off value for CRP was 7.18 mg/dL, with a sensitivity of 71.9% and a specificity of 68.1%. The best cut-off value for PCT was 0.09 ng/mL, with a sensitivity of 81.3% and a specificity of 78.7%. The PCT level had better sensitivity and specificity compared to the CRP level in distinguishing between bacterial infections and disease flares in autoimmune disease patients. The CRP level has no additive value when combined with the PCT level when differentiating bacterial infections from disease flares.
authors.affiliation: Division of Rheumatology, Department of Internal Medicine, Inha University Hospital, Incheon, Korea.
authors.forename: Kowoon
authors.initials: K
authors.lastname: Joo
authors.forename: Won
authors.initials: W
authors.lastname: Park
authors.forename: Mie-Jin
authors.initials: MJ
authors.lastname: Lim
authors.forename: Seong-Ryul
authors.initials: SR
authors.lastname: Kwon
authors.forename: Jiyeol
authors.initials: J
authors.lastname: Yoon
mesh_terms: D000328:Adult; D000368:Aged; D019540:Area Under Curve; D001327:Autoimmune Diseases / Q000150:complications / Q000175:diagnosis*; D001424:Bacterial Infections / Q000150:complications / Q000175:diagnosis*; D002097:C-Reactive Protein / Q000032:analysis; D002116:Calcitonin / Q000097:blood*; D015740:Calcitonin Gene-Related Peptide; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D011498:Protein Precursors / Q000097:blood*; D012372:ROC Curve; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
chemical_list: C000606589:CALCA protein, human; D011498:Protein Precursors; D002116:Calcitonin; D002097:C-Reactive Protein; D015740:Calcitonin Gene-Related Peptide