Finally, contrasting results of baseline and follow-up analyses are often observed and might be due to a difference in patient's recall when asked for lifetime events in comparison to events during a shorter and more recent period of time. In the COGA study, subjects were assessed at baseline regarding their current and lifetime characteristics. At the follow-up interview, they were again assessed for their current and lifetime characteristics and in addition, for most recent events during this period. Thus, individuals might recall these more recent events better than more remote features of their disorders. This also underscores the necessity for prospective studies which might provide more accurate data than solely baseline designs to reduce individual recall bias.
