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Table 1 Adverse drug reaction probability scale by Naranjo

From: Assessing causality by means of the Naranjo scale in a paediatric patient with life threatening respiratory failure after alemtuzumab administration: a case report

  Yes No Unknown
1. Are there previous conclusive reports on this reaction? + 1 0 0
2. Did the adverse event appear after the suspected drug was administered? + 2 −1 0
3. Did the adverse event improve when the drug was discontinued or a specific antagonist was administered? + 1 0 0
4. Did the adverse reaction reappear when the drug was readministered? + 2 −1 0
5. Are there alternative causes (other than the drug) that could on their own have caused the reaction? −1 + 2 0
6. Did the reaction reappear when a placebo was given? −1 + 1 0
7. Was the drug detected in the blood (or other fluids) in concentrations known to be toxic? + 1 0 0
8. Was the reaction more severe when the dose was increased, or less severe when the dose was decreased? + 1 0 0
9. Did the patient have a similar reaction to the same or similar drugs in any previous exposure? + 1 0 0
10. Was the adverse event confirmed by any objective evidence? + 1 0 0