Reported age at first drink was somewhat more stable in our sample than in prior studies (Bailey et al., 1992; Labouvie et al., 1997; Prause et al., 2007; Shillington and Clapp, 2000), with a Pearson correlation of 0.65 between the 2 reports and nearly two thirds of participants’ Time 2 reports differing by 1 year or less from Time 1 reports. However, stability of (dichotomous) early onset status was poor, with 56% of those initially classified as early users no longer reporting first drink prior to age 15 in their second reports. These findings suggest that results from studies classifying age at onset simply as early vs. non-early should be interpreted with caution, given the instability of such dichotomous classifications. In contrast to the large number of participants shifting from early status at Time 1 to non-early status at Time 2, only 8.8% followed the reverse pattern, providing further support for elevated rates of this upward shift in reported age at first drink among early onset drinkers (Parra et al., 2003; Shillington and Clapp, 2000).
