Question: Does Quetiapine and/or Olanzapine increase the risk of blood clots in adults of working age?

Answer:

Data from one, large and generally well conducted retrospective case control study indicated that current antipsychotic use may be linked with an increased risk of venous thromboembolism (VTE), within the first 30 days after the start of treatment. No increased risk was found for previous exposure to antipsychotic drugs (more than 60 days before the start of the study). The VTE risk associated with current use appeared to vary between individual antipsychotic drugs and neither all atypical antipsychotics nor olanzapine specifically were found to be associated with increased risk of VTE, however, it should be noted that the numbers of participants in individual drug and exposure time categories was often small.

Although the base population from which this study was sampled was large, a still larger dataset is need to adequately explore the relationship between the duration of use of antipsychotic drugs and risk of VTE and how this may vary between individual drugs; it is important to ensure that there are adequate numbers of study participants for each drug and exposure combination assessed.

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