Antipsychotics and risk of venous thromboembolism: A population-based case-control study

Original Research

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Authors: Anna K Jönsson, Erzsebet Horváth-Puhó, Staffan Hägg, Lars Pedersen, Henrik Toft Sørensen

Published Date March 2009 Volume 2009:1 Pages 19 - 26

DOI: http://dx.doi.org/10.2147/CLEP.S4969

Anna K Jönsson¹, Erzsebet Horváth-Puhó², Staffan Hägg³, Lars Pedersen⁴, Henrik Toft Sørensen⁴

¹Nordic School of Public Health, Gothenburg, Sweden; ²Centre for Registry Research, Aarhus C, Denmark; ³Division of Clinical Pharmacology, Linköping University, Linköping, Sweden; ⁴Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus C, Denmark

Abstract: During the last decade, the risk of venous thromboembolism (VTE) has been reported in users of antipsychotic drugs. However, the reports have been inconclusive. This study aimed to determine the relative risk of VTE in antipsychotic drug users. Using data from medical databases in North Jutland and Aarhus Counties, Denmark, and the Danish Civil Registration System, we identified 5,999 cases with a first-time diagnosis of VTE and, based on risk set sampling, 59,990 sex- and age-matched population controls during 1997–2005. Users of antipsychotic drugs were identified from population-based prescription databases and categorized based on filled prescriptions prior to admission date for VTE or index date for controls as current (at least one prescription within 90 days), recent (at least one prescription within 91–180 days), former (at least one prescription within 181–365 days) or nonusers (no recorded prescription within 365 days). Compared with nonusers, current users of any antipsychotic drugs had an increased risk of VTE (adjusted relative risk [ARR]: 1.99, 95% confidence interval [CI]: 1.69–2.34). Former users of any antipsychotic drugs had a nonsignificant elevated risk of VTE compared with nonusers (ARR: 1.54, 95% CI: 0.99–2.40, p-value: 0.056). In conclusion, users of antipsychotic drugs have an increased risk of VTE, compared with nonusers, which might be due to the treatment itself, to lifestyle factors, to the underlying disease, or to residual confounding.

Keywords: antipsychotic agents, venous thromboembolism, adverse effects, case-control study