Selecting healthy volunteers in specific populations: a retrospective analysis of clinical and laboratory screening

Healthy volunteers must undergo a medical examination before enrollment in a clinical trial. An increasing number of trials include specific populations designed to match the target populations of the drugs tested. Our study aimed at evaluating which investigations are the most appropriate in different sub-populations of healthy volunteers. Data from 350 healthy volunteers who attended our Research Center from 1997 to 2004 were retrospectively analysed. Volunteers were distributed into five sub-populations: young men, senior men, overweight men, young women, postmenopausal women. The screening procedure comprised a review of medical history, physical examination, electrocardiogram and laboratory tests. Ineligibility criteria were classified as non-medical causes, protocol specific medical causes and non-specific medical causes. A total of 148 subjects (42%) were not-eligible, mainly because of non-specific medical causes (111 subjects), including abnormal medical history (34.5% of all ineligibilities). Blood pressure abnormalities were frequent in all sub-populations except young women. Electrocardiographic abnormalities led to ineligibility of only five overweight men and one menopausal woman. Abnormal laboratory tests accounted for 19.6% of ineligibilities. In senior subjects and overweight men, serologies, liver function tests and lipid profile contributed importantly to the selection process. Low red cells count was the most frequent laboratory abnormality in young women. Erythrocyte sedimentation rate, phosphocalcic metabolism and standard clotting tests led to frequent insignificant and non-contributive abnormalities. Our study confirms that a complete review of medical history is essential and determines the major part of ineligibilities. Complementary laboratory tests are always needed and may be adjusted to the population considered.