title: The clinical usefulness of ESR, CRP, and disease duration in ankylosing spondylitis: the product of these acute-phase reactants and disease duration is associated with patient's poor physical mobility.
abstract: We evaluated the clinical usefulness of ESR, CRP, and disease duration in ankylosing spondylitis (AS) disease severity. There were 156 Chinese AS patients included in Taiwan. Patients completed the questionnaires, containing demographic data, disease activity (BASDAI), functional status (BASFI), and patient's global assessment (BASG). Meanwhile, patient's physical mobility (BASMI) and acute-phase reactants, including ESR and CRP levels were measured. Receiver operating characteristic (ROC) plot analysis was used to evaluate the performance of ESR, CRP, and disease duration in the AS patients. ESR mildly correlated with BASFI (r = 0.176, p = 0.028) and disease duration (r = 0.214, p = 0.008), and moderately correlated with BASMI (r = 0.427, p < 0.001). CRP moderately correlated with BASMI (r = 0.410, p < 0.001). By using ROC plot analysis, ESR, CRP, and disease duration showed the best and significant "area under the curve (AUC)", in distinguishing the AS patients with poor physical mobility (BASMI ≥ 3.6, the Median) (AUC = 0.748, 0.751 and 0.738, respectively, all p < 0.001), as compared to BASDAI, BASFI, and BASG. ESR × disease duration (AUC = 0.801, p < 0.001) and CRP × disease duration (AUC = 0.821, p < 0.001) showed higher AUC values than ESR or CRP alone in indicating poor physical mobility. For detecting poor physical mobility (BASMI ≥ 3.6) in the AS patients: ESR × disease duration (≥60.0 mm/h × year): sensitivity = 72.7 % and specificity = 72.8 %; CRP × disease duration (≥8.3 mg/dl × year): sensitivity = 72.7 % and specificity = 74.6 %. ESR, CRP, and disease duration are particularly related to AS patient's poor physical mobility. Combining the usefulness of acute-phase reactants and disease duration, the values of ESR × disease duration and CRP × disease duration demonstrate better association with poor physical mobility in AS patients.
authors.affiliation: Division of Allergy, Immunology and Rheumatology, Taipei Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, New Taipei, Taiwan.
authors.forename: Chun-Hsiung
authors.initials: CH
authors.lastname: Chen
authors.forename: Hung-An
authors.initials: HA
authors.lastname: Chen
authors.forename: Hsien-Tzung
authors.initials: HT
authors.lastname: Liao
authors.forename: Chin-Hsiu
authors.initials: CH
authors.lastname: Liu
authors.forename: Chang-Youh
authors.initials: CY
authors.lastname: Tsai
authors.forename: Chung-Tei
authors.initials: CT
authors.lastname: Chou
mesh_terms: D000328:Adult; D019540:Area Under Curve; D044466:Asian People; D015415:Biomarkers / Q000097:blood; D001799:Blood Sedimentation; D002097:C-Reactive Protein / Q000032:analysis*; D002681:China / Q000208:ethnology; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D018836:Inflammation Mediators / Q000097:blood*; D008297:Male; D008875:Middle Aged; D051346:Mobility Limitation; D011237:Predictive Value of Tests; D012372:ROC Curve; D012307:Risk Factors; D012720:Severity of Illness Index; D013167:Spondylitis, Ankylosing / Q000097:blood / Q000175:diagnosis* / Q000208:ethnology; D013624:Taiwan / Q000453:epidemiology; D013997:Time Factors; D055815:Young Adult
chemical_list: D015415:Biomarkers; D018836:Inflammation Mediators; D002097:C-Reactive Protein