The Republic of Ireland has one of the highest rates of mortality arising from ischaemic heart disease in the European Union. (WHO, 2001). Up to 45% of patients diagnosed with ischaemic heart disease (IHD) particularly myocardial infarctions suffer from depression, which is a significant contributor to the mortality observed in such patients (Hippisley-Cox et al., 2001). The extent to which such patients receive antidepressants is not known.

This study aims to examine whether patients receiving therapy for IHD were any more or less likely to be prescribed antidepressants compared with those not receiving IHD therapy (control group) The choice of antidepressant was also examined.

Using the Irish General Medical Services (GMS) Scheme prescription claims database for the Eastern region, patients were classified as having (n=8,603) or not having IHD (n=140,649) based on whether or not they had received both aspirin and nitrate prescriptions at any time during the study period but had not received any antidepressant therapy during a lead in period of 6 months (January 2000-June 2000). This cohort of IHD patients was then followed up for a period of 16 months (July 2000-October 2001) and was further classified as either a 'new ' or 'chronic' user based on the commencement and duration of use of IHD therapy. Adjusted odds ratio (OR for age and gender) and 95% confidence intervals for the prescription of antidepressants in patients receiving IHD therapy compared to those not receiving any such therapies was determined by logistic regression analysis.

Of 8603 patients receiving IHD therapy during the study period, 1016 (11.8%) were prescribed antidepressants. The overall adjusted OR for antidepressant use in those receiving IHD therapy compared to those not receiving any IHD therapy was 1.25 (95% CI=1.17,1.34, p<0.0001). New users of IHD therapy were more likely (p<0.001) to receive a prescription for antidepressants (OR 1.37; 95%CI=1.23,1.52) than chronic users (OR 1.18; 95%CI=1.08,1.29) when compared with those not receiving any therapy for IHD. In general, there was an overall greater use of selective serotonin re-uptake inhibitors (SSRI) (60.8%; n=618) compared with tricyclic antidepressants (23.7%; n=241) and other antidepressants (15.5%; n=157) such as monoamine oxidase inhibitors in patients receiving IHD therapy. Similar prescribing rates were observed in the non IHD group (56.2% vs. 26.3% vs.17.3%) for these drugs thus indicating no selective or preferential prescribing of SSRIs in IHD patients.

There is an increased initiation of antidepressant therapy in patients receiving IHD therapy compared to those not receiving any such therapy. This suggests that patients recently diagnosed with IHD are more likely to be treated for depression. The considerable use of tricyclic antidepressants which are known to be cardiotoxic is however of concern.

1. WHO World Health Statistics Annual 2001.
2. Hippisley-Cox J et al (2001) Br Med J 323: 666 - 669.
3. Gray J et al. (2000) Br Med J 321: 548-50.