Undetected comorbidities linked to increased mortality in schizophrenia

By Lucy Piper, Senior medwireNews Reporter

Patients with schizophrenia have elevated mortality, the leading causes of which appear to be ischemic heart disease and cancer, a Swedish national cohort study shows.

"Despite having more than twice as many contacts with the health care system than other people, schizophrenia patients had no increased risk of having a diagnosis of nonfatal ischemic heart disease or cancer but had a far greater mortality from these conditions, suggesting substantial underdiagnosis and/or treatment," the researchers comment.

Their findings suggest that the association is largely due to underdetection rather than less effective treatment, which they say highlights the need for more effective primary healthcare tailored to this population.

Casey Crump, from Stanford University in California, USA, and colleagues analyzed mortality and comorbidities diagnosed in any outpatient or inpatient setting in 6,097,834 Swedish adults, including 8277 with schizophrenia, over a follow-up period of 7 years (2003-2009).

On average, men with schizophrenia died 15 years earlier than the rest of the population, and women with schizophrenia 12 years earlier. The crude mortality rates per 1000 person-years were 32.5 and 27.7 for women and men with schizophrenia, compared with 15.7 and 15.3 for other women and men.

The most common comorbidities among schizophrenia patients were diabetes and chronic obstructive pulmonary disease, the risks for which were both increased about twofold.

The risk for death from these conditions was also increased, as well as for stroke, suicide, and accidents.

There was no increased risk for diagnoses of ischemic heart disease, hypertension, lipid disorders, cancer, or liver disease.

But the researchers found that schizophrenia patients had an increased risk for dying from ischemic heart disease and cancer (particularly lung, breast, and colon cancer), with respective hazard ratios of 3.33 and 1.71 for men and 2.20 and 1.44 for women.

This increased risk appeared to be due to underdiagnosis, with schizophrenia patients less likely than others to be diagnosed with these conditions, at 26.3% versus 43.7% for ischemic heart disease and 73.9% versus 82.3% for cancer.

The association between schizophrenia and all-cause mortality was greatest among women with schizophrenia and employed individuals, and lack of antipsychotic treatment was also associated with elevated mortality.

"The large health risks we observed in schizophrenia patients highlight the need for more effective primary medical care tailored to this population and better adherence to standard clinical guidelines," the researchers conclude.

"Risk modification and screening for cardiovascular disease and cancer are particularly important given the elevated mortality from these conditions."

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