Pharmacoeconomics and Safe Medication Use
Appendix 1. Adverse Drug Event Reporting Form (continued)
Modified Naranjo Criteria for Causality (also called ADR Probability Scale)
YES
NO
DONβT KNOW
(not conducted,
not reported)
SCORING
SYSTEM
1.β Are there previous reports (in the literature)
of this reaction? (If no, please provide docu-
mentation of search strategy)
+1
Based on the total
score, circle the
term that best
defines this ADR:
β₯ 9 Definite
5β8 Probable
1β4 Possible
β€ 0 Doubtful
2.β Did the ADR appear after the suspected drug
was administered, confirming a temporal
relationship? (If no, please explain)
+2
-1
3.β Did the ADR improve when the drug
was discontinued or a specific antagonist
was administered? (If no, please explain)
+1
4.β Did the ADR reappear when the drug was
readministered?
+2
-1
5.β Are there alternative causes (other than the
drug) that could have caused the ADR? (If
yes, please explain)
-1
+2
6.β Did the ADR reappear when a placebo was
given?
-1
+1
7.β Was the drug detected in the blood or other
fluids in toxic concentrations?
+1
8.β Evaluate the dose-response relationship;
was the ADR more severe when the dose
was increased or less severe when the dose
was decreased?
+1
9.β Did the patients have a similar reaction to the
same or similar drugs (i.e., same drug class)
in a previous exposure?
+1
10.β Consider signs, symptoms, and laboratory
values other than drug concentrations. Was
the ADR confirmed by objective evidence?
+1
Source: Naranjo CA, Busto U, Sellers EM, et al. A method for estimating the probability of adverse drug reactions. Clin Pharmacol Ther 1981;30:239-45.