Prevalence of antiphospholipid antibodies in psychiatric patients users and non‐users of antipsychotics

Past reports have suggested that antiphospholipid (aPL) antibodies may emerge as a response to antipsychotics treatment, as a high prevalence of aPL antibodies in antipsychotics users has been observed. However, no control group of non‐medicated psychiatric patients was included in these reports. In a cross sectional study we determined the prevalence of aPL antibodies in 333 psychiatric inpatients. We compared the proportions of positive aPL antibodytests between users and non‐users of antipsychotics with adjustments for potential confounders. The proportion of antipsychotics users carrying at least one aPL antibody ranged from 10·8% to 27·0% compared with 6·8% to 27·2% in non‐users (P = 0·24, P = 0·24) depending on the method of detection of lupus anticoagulant (LA). The prevalence of LA detected by dilute Russell viper venom time or partial thromboplastin time‐LA was not different between antipsychotics users and non‐users (8·1% vs. 5·4%, P = 0·53 and 18·4% vs. 18·2%, P = 0·22), as well as the prevalence of IgM and IgG anti‐β2‐glycoprotein‐I antibodies, IgM and IgG anti‐cardiolipin antibodies(3·8% vs. 2·0%, P = 0·75, 0·0% vs. 0·0%, P = not applicable, 1·1 vs. 1·4%, P = 0·91, 2·7% vs. 3·4%, P = 0·71). In conclusion, aPL antibodies were frequently found in patients with psychiatric diseases and no significant increase in the prevalence of aPL antibodies was observed in antipsychotics users.