A comparison of populations self-selected and randomly selected for coronary risk factor screening

Levels of coronary risk factors in 3,090 adults who sought screening over a 2-year period in Perth, Western Australia, were compared with those in 722 subjects who were selected at random to attend the screening center. Self-referred (SR) subjects were less likely than random-sample (RS) subjects to have suffered from, or be on treatment for, heart disease, hypertension, gout, or diabetes but were more likely to have a family history of premature heart disease. They were less likely to be current smokers and overweight (women only) but more likely to be sedentary at work and have higher mean serum cholesterol levels. SR also had more knowledge about coronary heart disease (CHD) and its causes and were more likely to believe that this knowledge had influenced their behavior, but were less likely than RS to be satisfied with their knowledge level. Smokers among SR were more likely to express a wish to give up smoking than smokers in the RS. These findings are consistent with previous observations. The differences, although statistically significant, were generally small and did not clearly favor one group with respect to total risk of CHD. Therefore the effectiveness of risk factor modification following screening should not be greatly affected by self-selection for screening. Effectiveness may be greater in self-selected subjects because of their apparently greater motivation toward risk factor change.