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Table 1 The Naranjo Causality Scale

From: Oromandibular dystonia: a serious side effect of capecitabine

 

Yes

No

Do not know

Score case

1. Are there previous conclusive reports on this reaction?

+1

0

0

+1

2. Did the adverse event occur after the suspected drug was administered?

+2

−1

0

+2

3. Did the adverse reaction improve when the drug was discontinued or a specific antagonist was administered?

+1

0

0

+1

4. Did the adverse reaction reappear when the drugs was readministered? (‘rechallenge’)

+2

−1

0

+2*

5. Are there alternative causes (other than the drug) that could have on their own caused the reaction?

−1

+2

0

+2

6. Did the reaction reappear when a placebo was given?

−1

+1

0

0

7. Was the blood detected in any body fluid in toxic concentrations?

+1

0

0

0

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

+1

0

0

0

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

+1

0

0

0

10. Was the adverse event confirmed by any objective evidence?

+1

0

0

+1

Scoring

≥9 = definite ADR

5-8 = probable ADR

1-4 = possible ADR

0 = doubtful ADR

  1. *We answered this question with ‘yes’. Although capecitabine was not readministered, biperiden was discontinued. By doing so, the patient could be re-exposed to the side-effects of capecitabine and its metabolites which in all probability had not been completely eliminated.