Quantifying links between acute myocardial infarction and depression, anxiety and schizophrenia using case register databases

Aims: To quantify the association between depression and acute myocardial infarction (AMI) in a large sample using case registers, and examine whether any such link is specific to depression or might more reflect mental illness status in general. Methods and results: Accessing the Danish Psychiatric Central Research Register (PCR), patients with a diagnosis of depression were extracted and followed for up to 24 years for episodes of AMI. We used mentally healthy age- and sex-matched controls, and as comparator diagnostic groups, we studied patients with anxiety and schizophrenia. A positive association between depression and AMI was found with an incidence rate ratio (IRR) of 1.16 (CI: 1.10-1.22). The association was not unique for the depressed individuals, but was also found for anxiety patients, where it was even stronger (IRR = 1.56, CI: 1.35-1.79) than for the depressed patients. A negative association (IRR = 0.77, CI: 0.65-0.91) was quantified for schizophrenia, arguing against any link with AMI being determined by psychiatric disorder status per se. Limitations: Being a register study, not all potential confounding variables could be examined. Conclusion: Findings quantify significant associations between depression and AMI as well as between anxiety and AMI, and argue that these two psychiatric disorders should be added to the list of risk factors to coronary artery disease. (C) 2007 Elsevier B.V. All rights reserved.