Background: Antiphospholipid antibody (aPL) positive patients and patients with purported chronic Lyme disease ('CLD') share many clinical features. After identifying significant aPL in sera of several index patients with 'CLD', we performed aPL tests on all patients referred in whom 'CLD' was suspected, diagnosed or treated.
Methods: All patients with suspected, diagnosed or treated 'CLD' and reportedly 'positive' Lyme assays were studied. aPL testing included anticardiolipin antibodies (aCL), anti-beta-2-glycoprotein-1 antibodies (anti-β2GP1) and lupus anticoagulant (LAC). Patients were classified into four newly described categories of CLD and data was analyzed.
Results: One hundred and six patients were evaluated, of whom 82% had neurologic symptoms and 51% rheumatologic symptoms. Eighty-eight of 106 (83%) patients had positive Lyme serologies (enzyme-linked immunosorbent assay [ELISA] 62/106, 58.4%; western blot [WB] 64/106, 60%), while 18/106 (16.9%) were negative or equivocal. aPL was found in all 'CLD' categories. aCL and/or anti-β2GP1 were positive in 85/106 (80%), with aCL present in 69/106 (65%) and anti-β2GP1 present in 69/106 (65%). For all assays, IgM isotypes predominated: WB 55/64 (85%), aCL 63/69 (91%), anti-β2GP1 52/69 (75%), aCL and/or anti-β2GP1 74/85 (87%). Anti-β2GP1 assays occurred in higher titer than aCL: 36/69 (52%) versus 63/69 (91%), p<0.001. Seventeen patients had aPL-related events. Only 12/106 (11.3%) had true post-Lyme syndromes (PLS), category IV, or late Lyme disease (LLD). Most patients had been treated for Lyme: 82/106 (79%).
Conclusion: aPL occurs frequently in patients with 'CLD'. IgM anti-β2GP1, IgM aCL and IgM WB were frequently found. Documented PLS or LLD was uncommon. The role of aPL in patients with 'CLD' needs further investigation.