Cardiovascular drug use and mortality in patients with schizophrenia or bipolar disorder: a Danish population-based study

BACKGROUND: Cardiovascular (CV) co-morbidity is one of the major modifiable risk factors driving the excess mortality in individuals with schizophrenia or bipolar disorder. Population-based studies in this area are sparse. METHOD: We used Danish population registers to calculate incidence rate ratios (IRRs) for CV drug use, and mortality rate ratios comparing subjects with schizophrenia or bipolar disorder with subjects with no prior psychiatric hospitalization. RESULTS: IRRs for CV prescriptions were significantly decreased in patients with schizophrenia or bipolar disorder compared with the general population. Among persons without previous myocardial infarction (MI) or cerebrovascular disease, persons with schizophrenia or bipolar disorder had an up to 6- and 15-fold increased mortality from all causes or unnatural causes, respectively, compared with the general population, being most pronounced among those without CV treatment (16-fold increase). Among those with previous MI or cerebrovascular disease, excess all-cause and unnatural death was lower (up to 3-fold and 7-fold increased, respectively), but was similar in CV-treated and -untreated persons. CONCLUSIONS: The present study shows an apparent under-prescription of most CV drugs among patients with schizophrenia or bipolar disorder compared with the general population in Denmark. The excess of mortality by unnatural deaths in the untreated group suggests that the association between CV treatment and mortality may be confounded by severity of illness. However, our results also suggest that treatment of CV risk factors is neglected in these patients.