Third, ICU admission could be both a confounder and consequence of the outcome. To account for this, we adjusted for ICU admission before the first dose of ceftriaxone and PPI as a covariate. The subgroup analysis excluding patients admitted to the ICU before ceftriaxone and PPIs were prescribed showed similar results. In this subgroup analysis, we also included transfer to the ICU after the start of ceftriaxone and PPI therapy as an exploratory outcome.