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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.