209 - Outcomes

Outcomes

212 The Maudsley® Prescribing Guidelines in Psychiatry CHAPTER 1 Mechanisms Several mechanisms have been suggested to explain the association between antipsychotics and thromboembolism. These proposed mechanisms are outlined in Box 1.3. Outcomes Increased risk of thromboembolism is reflected in numerous published reports of ­elevated incidence of pulmonary embolism,17 stroke18 and myocardial infarction.19 A 2022 study suggested that antipsychotics increase the risk of fatal thromboembolism (OR 6.68),17 although, again, the absolute risk remains low. Box 1.3  Proposed mechanisms for antipsychotic-­associated venous thromboembolism11–15 Sedation* Obesity* Hyperprolactinaemia* Elevated phospholipid antibodies Elevated platelet aggregation** Elevated plasma homocysteine Elevated tissue plasminogen activator Elevated platelet count * Some evidence that these factors are not the mechanism for antipsychotic-­induced thromboembolism.16 ** In vitro data suggest radically different effects on platelet aggregation for different antipsychotics.12 Table 1.49  Findings of meta-­analyses of the risk of pathological blood clotting. Reference Relative risk vs no use Comments Number of studies included FGAs (OR) SGAs (OR) All anti-­ psychotics (OR) Di et al, 20219 1.83 VTE/PE 1.75 VTE 1.53 VTE Highest risk in younger patients (<60 years). Low-potency FGAs highest risk. 3.79 PE 3.69 PE 2.06 VTE/PE 1.60 VTE/PE Liu et al, 202110 1.47 VTE/PE 1.62 VTE/PE 1.55 VTE New users of antipsychotics had higher risk than continuing patients. Risk slightly elevated with higher doses vs low doses. Similar effect sizes for FGA vs SGA. 3.68 PE 2.01 VTE/PE FGA, first-­generation antipsychotic; OR, odds ratio; PE, pulmonary embolism; SGA, second-­generation antipsychotic; VTE, venous thromboembolism.