 Johan Denollet, professor of Medical Psychology at Tilburg University, Tilburg, The Netherlands, developed the construct based on clinical observations in cardiac patients, empirical evidence, and existing theories of personality.The prevalence of Type D personality is 21% in the general population and ranges between 18% to 53% in cardiac patients.Some early studies found that coronary artery disease (CAD) patients with a Type D personality have a worse prognosis following a myocardial infarction (MI) as compared to patients without a Type D personality.