discordant twins results in a more modest drop in the estimated HR for CSA for a sexually abused twin whose co-twin was also abused, thus leading to an overestimate of CSA-associated risk in these twins. Fourth, using a time-varying covariate to represent CSA avoids the issue of CSA being counted as a risk factor for alcohol use when the first drink is consumed at the same time as the first CSA experience, but it is still possible that the observed elevated risk for very early alcohol use in women with a history of CSA reflected alcohol use in the context of later sexual abuse experiences.
