Yang L, et al. - Previous studies have found depression to be negatively associated with the prognosis of both cardiovascular disease (CVD) and cancer, but this may partly reflect reverse causality. In this current investigation, depression was measured before the first diagnosis of CVD or cancer in order to limit the possibility of reverse causality. Pre-existing depression was shown to be associated with a worse prognosis of coronary heart disease, stroke and cancer. A need for focusing more on patients having chronic diseases with a history of depression was realized.