Depression and antidepressants may increase the risk of venous thromboembolism (VTE), according to a metaanalysis that included eight observational studies involving 960,113 people.
People with depression and those taking antidepressants were 31 and 27 per cent more likely respectively to develop VTE than controls. The link with antidepressants seemed to be a class effect: tricyclics increased VTE risk by 16 per cent, selective serotonin reuptake inhibitors by 12 per cent and other antidepressants by 59 per cent.
Further studies need to determine whether depression, antidepressants or both account for the link. For example, researchers could assess if individuals using antidepressants for conditions other than depression are also at increased risk.
Studies also need to determine the underlying mechanism, although previous studies offer some clues. For example, inflammation may contribute to depression and VTE. Depressed people also tend to be less mobile, while the blood of people with depression also shows a marked tendency to clot.