C-reactive protein level as a predictor of transient vs. sustained anticardiolipin antibody positivity

The antiphospholipid (APLA) syndrome is defined as the occurrence of venous or arterial thromboembolism or recurrent fetal loss in patients with a positive anticardiolipin (aCL) or lupus anticoagulant test on two occasions, 3 months apart. In this study, we sought to determine whether the level of C-reactive protein (CRP), a non-specific inflammatory marker, at the time of the initial positive aCL test is a predictor of the transient vs. sustained nature of the aCL. Patients with a positive aCL antibody test underwent high sensitivity (hs) CRP testing. A repeat aCL antibody assay was performed on a serum sample obtained 3-4 months later. The positive and negative predictive values of the hs-CRP assay as a predictor of the second aCL result were calculated and correlation between the hs-CRP result and second aCL result was determined. Fifty-four consecutive patients with a positive aCL test were studied. Forty-two had a positive aCL-2. The predictive value of a negative CRP test for a positive aCL-2 was found to be 82.5% (33 of 42 patients). A positive CRP was able to predict a negative aCL-2 in 35.7% of cases (nine of 14 patients). Our results suggest that the hs-CRP test may be useful in the assessment of patients with a positive aCL antibody test. A concurrently performed negative hs-CRP test result may be useful in making diagnostic and therapeutic decisions.