A case-control study of cardiovascular risk factors and cardiovascular risk among patients with schizophrenia in a country in the low cardiovascular risk region of Europe

Introduction: Patients with serious mental illness have increased cardiovascular risk factors and excess mortality from cardiovascular disease that are in part favored by adverse effects of treatment. Given the wide geographical variation of vascular atherosclerotic disease there is a recognized need for national studies. Methods: The prevalence of risk factors and estimated absolute and relative cardiovascular risk by means of SCORE risk charts were ascertained in 125 schizophrenia outpatients and 1721 age- and gender-matched primary care center users. Results: Patients with schizophrenia have a very high prevalence of cardiovascular risk factors. Higher values were observed for smoking (65.0%), clinical or laboratory dyslipidemia (59.1% and 52.0%), careless diet (78.4%), sedentary lifestyle (64.2%), overweight or obesity (64.2%) and abdominal obesity (50.9%). Lower values were observed for hypertension (25.0%), metabolic syndrome (21.9%), diabetes (9.6%) and alcohol abuse (4.0%). An association between risk factor exposure and disease was documented (odds ratio, [95% confidence limits]) for smoking (2.47 [1.68-3.64]), laboratory dyslipidemia (1.92 [1.33-2.77]), low HDL-C (2.12 [1.31-3.42]), careless diet (4.46 [2.88-6.90]) and sedentary lifestyle (1.79 [1.22-2.62]). A significant association between antipsychotics that are more likely to induce weight gain and overweight or obesity could not be demonstrated in this study. Hypertension was 46% lower in cases (n=26/125) than in controls (0.54 [0.34-0.84]). This rather surprising result could be explained by our finding of a negative association (p=0.01) between blood pressure levels and rate of benzodiazepine prescription among schizophrenia patients. The negative association documented in these patients by multivariate regression analysis (p=0.005) between hypertension and benzodiazepine prescription reinforces this explanation. Untreated hypertension, untreated dyslipidemia and untreated diabetes are strongly associated with schizophrenia (3.79 [1.63-8.81]), (3.79 [2.06-7.35]), (6.38 [1.725-23.59]), respectively. A significant difference in 10-year absolute risk of fatal cardiovascular disease between cases and controls aged 40 years or more could not be demonstrated in our study (p=0.054). Nonetheless, in younger individuals, higher levels of relative risk multiples in the 2-12 range were found in schizophrenia patients compared to controls (p<0.050). Conclusions: In schizophrenia patients, a high prevalence of cardiovascular risk factors and of neglected treatment was found. The great majority of cases and controls aged 40 years or more have low and comparable levels of absolute cardiovascular risk mortality. For those aged under 40 years, schizophrenia patients show higher relative cardiovascular risk than controls. These findings call for closer collaboration between psychiatrists and primary care providers. The finding of a lower prevalence of hypertension among cases seems to be associated with an apparent protective effect of benzodiazepines, which are frequently prescribed to patients with schizophrenia in Portugal.