People who have severe mental illness are at double to triple the risk of dying from coronary heart disease or stroke at all ages, compared with people who are not mentally ill, reported David P.J. Osborn, Ph.D., and his associates.
The social deprivation of the severely mentally ill and their higher rate of smoking do not explain this increased cardiovascular risk, and their use of antipsychotic medications “is only part of the explanation.” The exact mechanism underlying this increased vulnerability remains unknown, the researchers said.
Noting that the true burden of physical disease among the severely mentally ill has never been established, Dr. Osborn and his associates at the Royal Free and University College London tried to estimate the risks of heart disease, stroke, and cancer death using data from the United Kingdom's General Practice Research Database. “Precise estimation of the true population risk for CVD [cardiovascular disease] or cancer mortality requires data from large, representative populations followed up for periods long enough to include sufficient observed deaths,” they pointed out.
The GPRD covered some 8 million patients treated in 741 general practices throughout the United Kingdom between 1987 and 2002, and the sample included almost all those with severe mental illness at the time.
Compared with more than 300,000 randomly selected, matched control subjects who were free from severe mental illness, the 46,136 subjects with schizophrenia, schizoaffective disorder, bipolar disorder, delusional disorder, or other nonorganic psychoses showed triple the rate of death from coronary heart disease before age 50 and double the rate at aged 50–75 years.
Similarly, stroke mortality was 2.5 times higher in mentally ill people younger than 50 years and twice as high in those aged 50–75 years than it was in the controls, the investigators said (Arch. Gen. Psychiatry 2007;64:242–9).
In contrast, mortality from six of the seven most common cancers in the United Kingdom–colorectal, breast, prostate, stomach, esophageal, and pancreatic cancers–was no different between the control subjects and the mentally ill. Mortality from the seventh common malignancy, respiratory cancer, initially was higher in the severely mentally ill. However, after the data were adjusted to account for smoking and social deprivation, that difference was no longer significant.
Mentally ill people who did not take antipsychotic medications were at increased risk of coronary heart disease and stroke, and those who did take the medications were at even higher risk. People who took the highest doses were at the highest risk of cardiovascular death.
This dose-response relationship could be attributable to adverse drug effects at higher doses, or it could be that higher doses are simply a marker of the severity of mental illness, which itself may raise mortality risk, Dr. Osborn and his associates said.
The reasons why severe mental illness puts people at higher risk of CVD mortality remain unclear. It is possible that mentally ill patients may be less likely to present with CVD symptoms, to be correctly diagnosed, to be given correct treatment, and to adhere to treatment, the researchers said.
These findings underscore the fact that people with severe mental illness must be monitored for somatic conditions. Although the management of blood pressure, glucose levels, cholesterol levels, smoking, diet, and exercise may be best accomplished in the primary care setting, “psychiatric health care professionals cannot be viewed as exempt from responsibility for physical health monitoring,” Dr. Osborn and his associates noted.