Table 2 Naranjo causality scale for adverse drug reactions

Question/ Scoring Yes/No/Do not know or unavailable

Case 1

Case 2

Case 3

1. Are there previous conclusive reports on this reaction?1/0/0

1

1

1

2. Did the adverse event appear after the suspected drug was given? 2/-1/0

2

2

2

3. Did the adverse reaction improve when the drug was discontinued or a specific antagonist was given? 1/0/0

1

1

1

4. Did the adverse reaction appear when the drug was readministered? 2/-1/0

0

0

0

5. Are there alternative causes that could have caused the reaction? -1/2/0

0

0

0

6. Did the reaction reappear when a placebo was given?-1/1/0

0

0

0

7. Was the drug detected in any body fluid in toxic concentrations? 1/0/0

1

0

0

8. Was the reaction more severe when the dose was increased/increasing, or less severe when the dose was decreased? 1/0/0

0

1

1

9. Did the patient have a similar reaction to the same or similar drugs in any previous exposure? 1/0/0

0

0

0

Total

5

5

5

Scoring > 9 = definite adverse drug reaction (ADR)  5-8 = probable ADR  1-4 = possible ADR  0 = doubtful ADR