New approaches to fill the methods gap in pharmacovigilance

Studying long-term effects in databasesmethodological challenges Selection bias Who are long-term users? Health-seeking behavior Well-controlled Co-medicationIf selection to remain in the cohort is based on factorsrelated to outcome, then results will be biased Some analytic options Comparison of initiators vs. initiators and model time-varyinghazards Comparison of switchers vs. switchers considering cumulativemedication history from initiation until switch (dose, duration,etc).19