Recruitment from medical referrals and clinical laboratories

Medical referrals represent a recruitment source with a relatively low volume of initial contacts and entries and a high ratio of entries to initial contacts, while referrals from clinical laboratories comprise a relatively moderate volume of initial contacts, a low volume of entries and a moderate ratio of entries to initial contacts. Both sources require a relatively low effort level for the recruitment team. In the CPPT, all centers used these strategies, to provide, overall, 3% of initial contacts, 8% of first protocol visits and 10% of entries. Unwillingness to participate at the first protocol visit excluded less than one-half as many medical referrals as was observed for all sources, while referrals from clinical laboratories were excluded due to unwillingness to participate much more frequently than the all-source mean. Low yields preclude reliance on these sources for any but the smallest clinical trial.