[The value of erythrocyte sedimentation rate and C-reactive protein in evaluating disease activity in ankylosing spondylitis].
OBJECTIVE
To determine whether erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP) is more appropriate in measuring the disease activity in ankylosing spondylitis (AS).


METHODS
We studied 126 consecutive patients with AS. The external criteria for disease activity were Cowling clinical assessment of disease activity and the Bath AS disease activity index (BASDAI). In each measure we defined 3 levels of disease activity i.e. no activity, ambiguous activity and definite activity. The patients with AS were divided into 2 groups: those with spinal involvement only and those with peripheral arthritis as well. For each criterion of disease activity, the patients without activity and with definite activity were included in receiver operating characteristic curve, which was used to determine cutoff values with the highest sensitivity and specificity. We also calculated Spearman correlation.


RESULTS
The median ESR and CRP were 25.3 mm/1 h and 11.1 mg/L in the spinal group and 30.0 mm/1 h and 15.0 mg/L in the peripheral group. In both groups the Spearman correlation coefficients between ESR and CRP were around 0.30. There was no correlation between ESR, CRP, and the 2 disease activity variables (0.027-0.282). Sensitivity for both ESR and CRP was between 39.4 %and 81.3% for Cowling assessment of disease activity and the BASDAI, while specificity was between 40.0% and 86.7% for all disease activity measures.


CONCLUSIONS
It is concluded that neither ESR nor CRP is superior for assessing disease activity in ankylosing spondylitis.
Liu
Bin
B
Department of Immunology and Rheumatology, Qingdao Municipal Hospital, Qingdao 266011, China. binliu72314@163.com
Guo
Chuan-you
CY
Liu
Wen-qu
WQ
Wu
Ning
N
Xing
Qian
Q
D000328:Adult; D001799:Blood Sedimentation; D002097:C-Reactive Protein / Q000032:analysis*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D013167:Spondylitis, Ankylosing / Q000097:blood* / Q000503:physiopathology
D002097:C-Reactive Protein