Validity of polymyalgia rheumatica diagnoses and classification criteria in primary health care

PMR is an inflammatory disease with prominent morning stiffness and muscular tenderness, usually diagnosed in primary health care (PHC). The objectives were to examine the validity of PMR diagnoses in PHC and to validate the use of classification criteria for PMR.

Medical records for patients with a registered PMR diagnosis at two PHC facilities were reviewed. Patients were classified according to several sets of criteria. An independent review, with assessment of the PMR diagnosis, was performed by an experienced rheumatologist.

Of 188 patients, the PMR diagnosis was in agreement with the independent review in 60% overall, in 84% of those fulfilling a modified version of the ACR/EULAR classification criteria and in 52% of those who did not. The corresponding proportions for the Bird criteria were 66 and 31%, and for the Healey criteria 74 and 42%. In 74% of the medical records, documentation on morning stiffness was missing. Rheumatoid factor was tested in 22% and anti-CCP antibodies in 15%.

In this study of patients with PMR diagnosed in PHC, the diagnosis was supported by the independent review in 60% of the patients. Documentation on morning stiffness and testing for autoantibodies were limited. A modified version of the ACR/EULAR criteria can be used to identify patients with a valid PMR diagnosis in retrospective surveys but does not capture all PMR patients. The modified ACR/EULAR criteria may be more stringent than some of the older criteria sets.