On average, fewer patients experienced a pADE in the post-intervention period than in the baseline period (a reduction approximately by half). However, because of the underlying negative trend at baseline, this decrease cannot be attributed to the introduction of CPOE/CDSS. In four recent reviews of the effect of CPOE/CDSS on medication safety, only a few studies evaluated the impact on pADEs or ADEs; this is possibly due to the labor-intensive way the data needed to determine (p)ADEs must be collected and assessed.