Tracking Substance Abusers in Longitudinal Research: Understanding Follow‐Up Contact Difficulty

Studies examining follow‐up contact difficulty provide useful information for planning longitudinal studies and for assessing the validity of follow‐up data. Contact difficulty was examined among 96 substance abusers following substance abuse treatment. Interview completion rates at the 3‐month and 6‐month follow‐ups were 93 and 97%, respectively. The extent of contact efforts required to complete follow‐up interviews varied substantially but tended to be greater at the 3‐month follow‐up than at the 6‐month follow‐up. Contact difficulty was related to reuse of substances at the 3‐month and at the 6‐month follow‐ups with reusers requiring greater contact efforts than abstainers. None of the baseline individual and contextual variables examined significantly predicted level of contact effort at follow‐ups. Attrition‐related validity implications are discussed along with practical suggestions for planning tracking efforts.