Problem The rapid plasma reagin test (RPR) is performed frequently in clinical practice, particularly among reproductive age women. The phenomenon of the biologic false positive RPR is well-recognized, but its clinical significance is poorly characterized. Our objective was to assess the relationship between the false positive RPR and several established clinical and biological markers for thrombophilia and/or autoimmune disease.
Method of study We conducted a clinic-based, case–control study of 41 healthy, reproductive age women with history of a biologic false positive RPR and 30 control women with a negative RPR to assess the relationship between the false positive RPR and several established clinical and biological markers for thrombophilia and/or autoimmune disease. We used t-tests and constructed frequency tables for case–control comparisons.
Results Cases were significantly more likely than controls to have lupus anticoagulant present in serum, have a positive ANA, and a positive ANA with a titer of 1:320 or greater. Cases were also more likely to be positive for anticardiolipin antibodies and have a prolonged activated partial thromboplastin time, but the CIs for those point estimates included the null value. Eight participants tested positive for both lupus anticoagulant and ANA. All eight were in the case group.
Conclusion These results suggest that the RPR test might be used to identify a subset of women who warrant further testing for autoimmune and/or thromboembolic disease.