Retention of resistant subjects in longitudinal studies: description and procedures.

This paper discusses efforts to retain resistant subjects (N = 88) in a prospective research project which investigates the effects of prenatal substance use on pregnancy and infant outcome. Resistant subjects were women for whom we had valid addresses and/or phone numbers. They did not refuse to participate but were reluctant to schedule appointments and/or keep scheduled appointments. The persistent resistance we encountered led us to develop procedures which established and maintained rapport with resistant respondents and facilitated access to the 18-month assessment. No significant differences were found between the resistant participants and nonresistant subjects on six sociodemographic factors and on substance use. However, resistant subjects were significantly more depressed than nonresistant subjects. Anxiety and hostility did not differ at any time point. Resistant subjects who were finally interviewed, reported a significantly higher number of recent life events than nonresistant subjects at the 18-month postpartum interview. The follow-up rates for retaining the 88 resistant subjects were 44.3, 72.7, and 79.6% at Phases 4, 5. and 6, respectively.