title: Erythrocyte sedimentation rate and C-reactive protein in the evaluation of disease activity and severity in polymyalgia rheumatica: a prospective follow-up study.
abstract: OBJECTIVE
  To determine the frequency and clinical features of patients with polymyalgia rheumatica (PMR) and normal erythrocyte sedimentation rate (ESR) at diagnosis or during relapse/recurrence. To evaluate the usefulness of C-reactive protein (CRP) and ESR in the assessment of PMR activity.
  
  
  METHODS
  A prospective follow-up study on 177 consecutive patients meeting the criteria for PMR diagnosed over a 5-year period was conducted in two Italian secondary referral centers of rheumatology. At diagnosis and during follow-up, ESR (Westergren method) and CRP (nephelometry) were measured in all patients. Phenotypic analysis of lymphocyte subpopulations was performed on 78 PMR patients at diagnosis. A two-color technique using the association of specific monoclonal antibodies was applied. A control group consisting of 18 healthy adults older than 60 years was matched for age and sex with the PMR patients.
  
  
  RESULTS
  Ten of 177 (6%) patients had normal ESR values at diagnosis (< or = 30 mm/h). Patients with normal ESR were predominantly men and had lower CRP levels; systemic signs and symptoms were more frequent in patients with higher ESR. The percentages of circulating CD8+ cells were similar in the two groups. CRP values at diagnosis were normal in only 2 of 177 (1%) patients. CRP values were elevated in 9 of 10 patients with normal ESR at diagnosis. Twenty-five episodes of relapse/recurrence with normal ESR occurred in 17 patients. CRP was high in 62% of these episodes. Results of univariate analysis indicated that the 10th percentile for ESR (40 mm/h) and the 70th percentile for CRP (7.8 mg/dL) values at diagnosis were the best cutoff points that discriminate between patients with and without relapse/recurrence. Cox proportional hazards modeling showed that ESR greater than 40 mm/h and CRP greater than 7.8 mg/dL at diagnosis were the two variables that independently increased the risk of relapse/recurrence. However, the relative risk related to ESR was twice than that related to CRP (4.9 vs 2.1).
  
  
  CONCLUSIONS
  PMR with a normal ESR at diagnosis was infrequent in our study compared with previous studies. ESR was a superior predictor of relapse than CRP. However, CRP was a more sensitive indicator of current disease activity.
authors.affiliation: Unità Reumatologica, 2nd Divisione di Medicina, Ospedale di Prato, Italy. fcantini@conmet.it
authors.forename: F
authors.initials: F
authors.lastname: Cantini
authors.forename: C
authors.initials: C
authors.lastname: Salvarani
authors.forename: I
authors.initials: I
authors.lastname: Olivieri
authors.forename: L
authors.initials: L
authors.lastname: Macchioni
authors.forename: A
authors.initials: A
authors.lastname: Ranzi
authors.forename: L
authors.initials: L
authors.lastname: Niccoli
authors.forename: A
authors.initials: A
authors.lastname: Padula
authors.forename: L
authors.initials: L
authors.lastname: Boiardi
mesh_terms: D000368:Aged; D001799:Blood Sedimentation; D002097:C-Reactive Protein / Q000032:analysis*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D011111:Polymyalgia Rheumatica / Q000097:blood / Q000175:diagnosis* / Q000503:physiopathology*; D011446:Prospective Studies; D012008:Recurrence; D012307:Risk Factors; D012720:Severity of Illness Index
chemical_list: D002097:C-Reactive Protein