Background: The relationship between depression and bipolar disorders and cardio-vascular diseases has been studied previously although the direction of the correlation is investigated less often. The present study examines the prevalence of hypertension among Danish psychiatric patients admitted with a diagnosis of bipolar affective disorder (BP) and controls.
Methods: Demographic, medical and psychiatric data on 25,339 BP patients and 113,698 controls were extracted from The Danish Psychiatric Central Research Register, The Danish National Patient Registry - for somatic patients, The Danish Civil Registration System, and The Danish Causes of Death Registry. Similar information about patients with schizophrenia and anxiety was collected for comparison.
Results: Hypertension was overrepresented in BP: IRR = 1.27, 95% confidence interval (1.16 to 1.39). This association was also found in anxiety patients: IRR = 1.96 (1.73 to 2.22), but not among patients with schizophrenia: IRR = 0.93 (0.77 to 1.14).
Limitations: The study uses nationwide data based on administrative health service registers. The data therefore are historical and heterogeneous samples.
Conclusions: A significant increase in levels of hypertension in BP patients was observed which may explain some of the increased cardio-vascular morbidity/mortality in BP patients.