To ascertain the frequency of polymyalgia rheumatica (PMR) with a normal erythrocyte sedimentation rate (ESR; < or = 30 mm/hour) and to determine any defining clinical characteristics.
A retrospective chart review study of all patients meeting the clinical criteria for PMR seen over a 5-year period in a hospital and an office-based rheumatology practice.
We evaluated 117 patients; 26 (22.2%) had a pretreatment ESR of < or = 30 mm/hour (mean +/- SD 19.8 +/- 7.5 versus 74.4 +/- 30.3 mm/hour for elevated ESR group; P<0.0001). Of the 26 normal ESR patients, 15 (58%) were female compared with 74 of the 91 elevated ESR patients (81%) (P<0.02, by Fisher's exact test). The mean hemoglobin concentration was significantly lower in the elevated ESR population (mean +/- SD 1.23 +/- 0.15 gm/liter versus 1.38 +/- 0.11 gm/liter; P<0.0001). The duration of symptoms prior to treatment with prednisone was significantly longer for patients with a normal ESR (149 +/- 95 days versus 103 +/- 95 days for elevated ESR patients; P<0.04).
In our series, PMR with a normal ESR accounted for approximately one-fifth of all PMR patients, more commonly in men. The lack of characteristically abnormal laboratory findings may result in a delay in the proper diagnosis and management of this condition.