The effect of "usual care" on cardiovascular risk factors in a clinical trial.

The use of referral to "usual care" (UC) for participants in randomized clinical trials satisfies the need for a control group who receive medical attention at the level of community standards. However, it has been suggested that this method, which may include follow-up with multiple examinations to collect trial information, may actually enhance quality of care. To determine the effect of this UC status, 64 UC men from the Multiple Risk Factor Intervention Trial (MRFIT) were matched on serum cholesterol (SC), diastolic blood pressure (DBP), and age with men who had similar characteristics at the initial recruitment screening but were not selected for the trial. Both groups were remeasured an average of 45 months after the initial recruitment. DBP at the second measurement was lower in both groups (11 mm Hg) and did not differ between groups. The percentage taking blood pressure medications was similar. SC was unchanged in either group. Reduction in risk observed in this MRFIT usual care group appears to be related to improved preventive practice in the community, specifically in blood pressure treatment. The additional effect of participation in a clinical trial as a control subject appears minimal for these risk characteristics.