Background: Antiphospholipid syndrome (APS) is the most common acquired thrombophilia. Diagnosis is based on clinical criteria and the presence of antiphospholipid antibodies (aPLs) above the 99th percentile of a reference group. Data on the distribution of aPL in the population are limited. The distribution of aPL including diagnostic cutoffs should be determined in a population-based cohort.
Methods: The Gutenberg Health Study (GHS) is a population-based cohort aged 35-74 years. We determined the presence of antibodies against cardiolipin (aCL, IgG, and IgM), β2-glycoprotein I (anti-β2GPI, IgG, and IgM), and domain 1 of β2-glycoprotein I (anti-domain 1, IgG) in a sample of 4979 participants.
Results: aPL titers were similar in the whole sample and in an apparently healthy subgroup of 1049 individuals. There was a strong age-dependent increase of both aCL and anti-β2GPI IgM, while aPL IgG titers were stable or tended to decrease with age. A relevant decrease was observed for aCL IgG in women and anti-domain 1 IgG in both sexes. There was no association of aPL titers with a history of venous thromboembolism (VTE).
Conclusions: Our data show that for IgM aPL, age-dependent reference ranges should be used. In fact, the controversy regarding the clinical utility of IgM aPL might be related to the use of inappropriate reference ranges among other causes. In our population, aPLs were not associated with a history of VTE.