Patients with schizophrenia, bipolar disorder, or depression have a significantly increased risk of tobacco-related mortality.
Among more than 591,000 such patients, tobacco-related deaths were about doubled, compared with the general population, Russell C. Callaghan, Ph.D., and his colleagues reported (J. Psych. Res. 2014;48:102-10).
In the study, the researchers analyzed the death records of patients who had been hospitalized with an ICD-9 primary psychiatric diagnosis in California between 1990 and 2005. Mortality estimates for conditions related to tobacco use comprised 53% of the total deaths in the schizophrenia cohort, 48% of deaths in the bipolar cohort, and 50% in the depression cohort, wrote Dr. Callaghan, associate professor in the Northern Medical Program at the University of Northern British Columbia, Prince George, and his associates.
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Lack of regular cancer screenings and insufficient tobacco use counseling could contribute to higher death rates for patients with schizophrenia and bipolar disorder.
The SMRs (standardized mortality ratios) for tobacco-related conditions were 2.45 for those in the schizophrenia group, 1.57 for the bipolar cohort, and 1.95 for the depression cohort. Cancer deaths were elevated among those with schizophrenia and depression, with SMRs of 1.3 among those with schizophrenia and 1.22 among those with depression. The risk was not increased among those with bipolar disorder, a finding that the investigators found to be surprising.
In addition, the schizophrenia, bipolar disorder, and depression groups all had increased rates of cardiovascular disease (SMRs of 2.46, 1.56, and 1.95, respectively). They also showed significantly higher SMRs for respiratory diseases (3.7, 2.4, and 2.7), wrote Dr. Callaghan, who also is affiliated with the Centre for Addiction and Mental Health in Toronto, and his associates.
Two factors are probably driving the excess mortality, they noted: insufficient tobacco use counseling and treatment, and the absence of regular cancer screenings.
The investigators cited several limitations. Because their cohort assignment algorithm "relied upon inpatient ICD-9 diagnoses of schizophrenia, bipolar disorder, and depression," the sample is based on those with fairly severe illness and might not have included those who had limited access to care. In addition, the medical records that were examined did not include information about the "presence, frequency, intensity, or duration of tobacco use," they wrote.
Despite those limitations, the findings suggest that addressing tobacco use in those groups is a "critical clinical and public health concern," they said.
"Our results stand as a call for increased recognition of the full harmful impact of tobacco use in these populations, as well as the urgent need to develop and implement strategies to reduce tobacco-related harms," Dr. Callaghan and his associates wrote.
The study was sponsored by the Centre for Addiction and Mental Health. The authors reported that they had no conflicts of interest.
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