Adverse drug reactions are appreciably harmful or unpleasant reactions resulting from an intervention related to the use of medical products, which predicts hazard from future administration and warrants prevention or specific treatment, or alteration of the dosage regimen, or withdrawal of the product. Given medical case reports extracted from MEDLINE, the task is to classify whether the case report mentions the presence of any adverse drug reaction. Classify your answers into non-adverse drug event and adverse drug event.
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Question: Propylthiouracil-induced sensorineural hearing loss associated with antineutrophil cytoplasmic antibodies.

Answer: adverse drug event


Question: INTRODUCTION: Despite high success rates with free-tissue transfer, flap loss continues to be a devastating event.

Answer: non-adverse drug event


Question: The authors conclude that among patients taking high doses of oral niacin only those who experience visual symptoms need to be ophthalmologically evaluated.

Answer:
adverse drug event