WHO PARTICIPATES IN A FAMILY STUDY

Potential subject participation biases in a family study of outpatient s with mood disorders and personality disorders (PDs) were explored at three levels: (1) differences between probands who granted permission to contact all relatives, those who gave permission to contact only a subset of relatives, and those who denied permission to contact any r elatives; (2) differences between relatives whom the proband granted p ermission to contact and those whom the proband denied permission to c ontact; and (3) for the relatives who could be contacted, differences between those who agreed to participate and those who declined. Subjec ts included 156 outpatients with mood disorders and PDs and 611 of the ir first-degree relatives. Axis I and II disorders in probands and rel atives were evaluated using structured diagnostic interviews. In addit ion, informant reports on relatives were obtained from family history (FH) interviews. Results indicated that probands who gave and who with held consent to contact their relatives did not differ significantly o n most variables. However, relatives whom we were not permitted to con tact were significantly more likely to have drug abuse and PDs. Finall y, of the relatives we were permitted to contact, there were few diffe rences between those who participated in the study and those who refus ed to participate. These findings indicate that the greatest risk of s ampling bias in family studies stems from probands' reluctance to gran t access to relatives with drug abuse and PDs. Copyright (C) 1995 by W .B. Saunders Company