Table 2.

The top five medication alerts occurring at least 20 times that were generated by system 2 and had the highest positive predictive values

Alert text	Nrelevant†	Ntotal‡	PPV* (%)
Advice: give a proton pump inhibitor	44	60	73.3
Beware of induction or exacerbation of hyperkalemia	15	21	71.4
Clopidogrel+omeprazole/esomeprazole§	13	20	65.0
This drug requires dosage adjustment in renal function impairment. Determine renal function, since the renal function is unknown in this patient.	19	55	34.5
This drug requires attention when the serum potassium level is high (>5 mmol/l).	14	41	34.1

^*PPV (positive predictive value)= $\frac{\text{number of relevant medication alerts}}{\left(\text{number of relevant medication alerts + number of irrelevant medication alerts}\right)}$.

^†N_relevant indicates the number of clinically relevant medication alerts.

^‡N_total indicates the total number of medication alerts.

^§At the time this study was conducted, this interaction had just been noted as relevant by various (inter)national authorities. However, the effect of the combination of clopidogrel with omeprazole on cardiovascular events remains controversial.^{22 23}