Anticardiolipin antibody levels predict flares and relapses in patients with giant-cell (temporal) arteritis. A longitudinal study of 58 biopsy-proven cases

Objective. To evaluate the usefulness of anticardiolipin antibodies (aCL) i n identifying flares and relapses in giant-cell arteritis. Methods. We studied 58 consecutive patients with biopsy-proven temporal gia nt-cell arteritis. C-reactive protein and aCL serum levels were measured si multaneously at the time of diagnosis and at each out-patient visit until r ecovery. All observed episodes of a rise in C-reactive protein attributable to a precise cause, for which the simultaneous measurement of aCL was avai lable, were analysed. Results. The mean duration of clinical observation and serum aCL assessment was 34 +/- 18 and 24 +/- 11 months, respectively. Anticardiolipin antibody positivity (IgG or total antibodies greater than or equal to 20 U) before treatment was found before treatment in 27 cases (46.6%) (mean 45.6 +/- 25 U/1, range 20-110 U). Levels of aCL decreased below 10 U with appropriate t reatment in all patients except one, after a variable delay. No rise in aCL levels was recorded subsequently in any patient whose disease was controll ed permanently. A significant rise in aCL was recorded in 20 of 27 (74%) of the flares or relapses of giant-cell arteritis, including seven of 12 flar es in seven patients whose initial aCL level was <20 U vs none of the 28 in flammatory episodes unrelated to giant-cell arteritis (P < 0.0000001). IgM aCL, infrequently found at diagnosis, was not associated with signs of dise ase activity. Conclusion. Serum aCL levels are useful in the detection of flares and rela pses in giant-cell arteritis, with fairly good sensitivity (74%) and a spec ificity of 100%, and can be of value in distinguishing subclinical flares f rom infection.