Serum procalcitonin for discrimination between septic and non-septic arthritis.
BACKGROUND
Early differentiation between septic and non-septic arthritis is difficult. A previous study showed promising diagnostic accuracy of serum Procalcitonin (PCT) in septic arthritis, limited by a low sensitive PCT test kit.


OBJECTIVE
To investigate the diagnostic value of PCT in patients with septic and non-septic arthritis using a novel test with low detection limit.


METHODS
Forty-two patients, 28 with non-septic and 14 with septic arthritis were prospectively included. For each patient, gram stain, culture and polarization microscopy of synovial fluid was done and PCT, C-reactive protein (CRP), white blood cell count, uric acid and blood cultures were taken. Patients with septic arthritis, patients with non-septic arthritis with and without concomitant infection were compared.


RESULTS
Patients with septic arthritis had a significant higher PCT concentration than patients with non-septic arthritis (p<0.0001). At a cut-off of 0.1 (0.25) ng/ml, sensitivity for septic arthritis was 100(93)% and specificity 46(75)%. Specificity rose to 93% after exclusion of patients with non-septic arthritis and concomitant infection. Both sensitivity and specificity for the diagnosis of septic arthritis were higher for PCT than CRP.


CONCLUSIONS
Our data suggest that PCT seems to be a highly sensitive and specific marker for septic arthritis, depending on the clinical setting. Further studies are warranted.
Hügle
T
T
Department of Rheumatology, University Hospital Basel, Switzerland. hueglet@uhbs.ch
Schuetz
P
P
Mueller
B
B
Laifer
G
G
Tyndall
A
A
Regenass
S
S
Daikeler
T
T
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001168:Arthritis / Q000097:blood* / Q000175:diagnosis*; D001170:Arthritis, Infectious / Q000097:blood* / Q000175:diagnosis* / Q000382:microbiology; D015415:Biomarkers / Q000097:blood; D002097:C-Reactive Protein / Q000378:metabolism; D002116:Calcitonin / Q000097:blood*; D015740:Calcitonin Gene-Related Peptide; D016022:Case-Control Studies; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008089:Listeria monocytogenes / Q000472:pathogenicity; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011498:Protein Precursors / Q000097:blood*; D012680:Sensitivity and Specificity; D013211:Staphylococcus aureus / Q000472:pathogenicity; D013292:Streptococcus agalactiae / Q000472:pathogenicity; D014527:Uric Acid / Q000378:metabolism
D015415:Biomarkers; C000606589:CALCA protein, human; D011498:Protein Precursors; D014527:Uric Acid; D002116:Calcitonin; D002097:C-Reactive Protein; D015740:Calcitonin Gene-Related Peptide