Patients have the option to participate in many investigations of non-compliance for medical recommendations. The question can therefore be raised about whether a tendency to volunteer for medical research is consistent with a tendency to comply with other medical treatment requests. In short, are volunteers or participants generally compliant relative to nonparticipants? This study examined past compliance for recommended follow-up appointments in patients who were requested to participate in a blood pressure assessment program and in a subsequent study on compliance for hypertensive regimens. Hospital records of the patients were reviewed for the two-year period that preceded the request to participate. Analysis of variance demonstrated significant differences in past compliance for participants and nonparticipants. The results of this study suggest that investigations of noncompliance have used samples that are select for compliant behavior. The implications of this study on compliance research are discussed.
