Factors that influence the eligibility of cases for inclusion in clinical trials. The Lung Cancer Chemotherapy Study Group of the Japan Clinical Oncology Group

BACKGROUND: It is important to minimize the incidence of ineligible casesto improve the quality of clinical trials. To determine factors which mayinfluence the incidence of ineligible cases, the incidence of and reasonsfor ineligibility in clinical trials were retrospectively analyzed.METHODS: We retrospectively examined the incidence of and reasons forineligibility for inclusion in eight clinical trials conducted by the LungCancer Chemotherapy Study Group of the Japan Clinical Oncology Group andfour trials financed by trust funds from a pharmaceutical company. RESULTS:In these 12 clinical studies, the incidence of ineligibility was 4.2%(32/762) (range 0-10.6%). Specific factors that might influence theincidence of ineligible cases were then analyzed. There was a significantdifference in the incidence of ineligibility between the methods ofregistration (P < 0.05). The incidences using a central registration andwithout using a central registration system were 2.8% (9/322) and 5.2%(23/440) respectively. We also analyzed ineligible cases in clinicalstudies published in the Journal of Clinical Oncology. In clinical studiespublished in the Journal of Clinical Oncology recently and 10 years ago,the incidences of ineligible cases were 5.0% (942/18 878) and 4.1%(206/4995) respectively. In clinical studies on lung cancer published inthe Journal of Clinical Oncology from 1984 to 1995, the incidence ofineligible cases was 4.7% (900/19,116). There was no significant differencein the incidence of ineligible cases between our 12 studies and the Journalof Clinical Oncology clinical studies by the chi 2 test (P > 0.05).CONCLUSIONS: We conclude that the incidence of ineligible cases in ourstudies is similar to that in clinical trials published in the Journal ofClinical Oncology. Central registration systems are useful for checking forineligibility, and to increase the quality of clinical trials.