Objective: To determine the incidence of elevated levels of anticardiolipin antibody (aCL) in patients with newly diagnosed polymyalgia rheumatica (PMR) and/or giant cell arteritis (GCA); and to determine the relationship between these antibodies at diagnosis and subsequent course of the disease over a period of 2 yrs.
Methods: Ninety-eight consecutive patients with PMR and/or GCA were examined for the presence of aCL, at presentation and every 6 mo for 2 yrs. Sixty-four patients had PMR alone, 22 had coexistent PMR and GCA, and 12 presented with pure GCA. Patients presenting with suspected clinical diagnosis, overt or covert, of GCA were subjected to temporal artery biopsy from the symptomatic side within 3 days of presentation. Appropriate serological, biochemical, and hematological investigations were undertaken at presentation and subsequently at times of periodic assessments. One hundred healthy age and sex matched elderly subjects were also screened for the presence of aCL as a control group.
Results: Elevated levels of aCL were detected in 20 patients at presentation. These included 9 patients with PMR/GCA and 11 patients with pure PMR. During followup, 10 patients with pure PMR at presentation developed GCA. These comprised 5 of the 11 patients with high aCL at presentation and 5 of the 53 patients with normal levels of aCL at presentation. This was statistically significant with relative risk (4.82, 95% CI, 1.72-13.51) of developing GCA in the presence of PMR and a high aCL at presentation. Furthermore, 3 of the 5 patients with pure GCA and high aCL at presentation progressed to severe vascular complications (stroke, 2; anterior ischemic optic neuritis, 1) compared to none of the other patients in the study. Elevated levels of antineutrophilic cytoplasmic antibody were also analyzed and detected in only 4 patients, 3 with pure PMR and one with biopsy proven GCA.
Conclusion: This prospective study suggests that a significant number of patients with PMR and/or GCA with elevated levels of aCL at presentation have increased risk of developing GCA or other major vascular complications. It is possible that aCL may be an independent prognostic marker for future vascular complications in patients with PMR and/or GCA.