Risk factors for coronary heart disease in people with severe mental illness

Osborn et al (2006) compared risk factors for coronary heart disease (CHD) in people with and without severe mental illness (SMI) in primary care.

A number of points in the results, discussion and conclusions seem unjustified and are potentially misleading. For example, the statement that patients with SMI had a significantly raised CHD risk score is based upon the unadjusted risk. After adjustment for age and gender the odds ratio dropped below the level of statistical significance and fell further to a non-significant value of 1.3 (95% CI 0.7-2.7) after considering employment status. The authors' claim that ‘we have demonstrated that SMI itself can incur CHD risk, over and above that associated with the socioeconomic deprivation experienced by these patients’ is not justified.

This claim is repeated in the abstract: ‘excess risk factors for CHD are not wholly accounted for by medication or socioeconomic deprivation’. This statement seems either unproven or reducible to the fact that smoking is more common among people with SMI. Such a conclusion is scarcely novel and clearly does not explain the excess mortality observed in patients with SMI (Joukamaa et al, 2006). The fact that diabetes is both more common among people with SMI and much less explicable in terms of their deprivation or demographics receives relatively little comment, despite having particular relevance for their healthcare needs.