Table 1.

Formulas and criteria for generating signals of ROR, PRR and MHRA.

Method	Formula	Criteria and threshold
ROR	$\text{ROR}=\frac{\left(\text{a}/\text{c}\right)}{\left(\text{b}/\text{d}\right)}$ $95\%\mathrm{Cl}={\mathrm{e}}^{\ln (\mathrm{ROR})\pm 1.96\sqrt{\frac{1}{a}+\frac{1}{b}+\frac{1}{c}+\frac{1}{d}}}$	a≥3 and lower limit of 95%CI >1
PRR	$\text{PRR}=\frac{\text{a}/\left(\text{a}+\text{b}\right)}{\text{c}/\left(\text{c}+\text{d}\right)}$ $95\%\mathrm{Cl}={\mathrm{e}}^{\ln (\mathrm{PRR})\pm 1.96\sqrt{\frac{1}{a}+\frac{1}{b}+\frac{1}{c}+\frac{1}{d}}}$	a≥3, PRR≥2 and lower limit of 95%CI >1
MHRA	${\text{χ}}^2=\frac{\text{n}{\left(\left|\text{ad}-\text{bc}\right|-\frac{\text{n}}{2}\right)}^2}{\left(\text{a}+\text{b}\right)\left(\text{a}+\text{c}\right)\left(\text{b}+\text{c}\right)\left(\text{c}+\text{d}\right)}$	a≥3 and χ2≥4

a: number of reports containing both the suspect drug and the suspect ADR;

b: number of reports containing the suspect ADR with other medications (except the drug of a);

c: number of reports containing the suspect drug with other ADRs (except the event of a);

d: number of reports containing other medications and other ADRs.