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.
--------
Question: Transthoracic or better transoesophageal echo-cardiography and Doppler are by far the most accurate diagnostic tools that can entirely replace angiographic assessment.

Answer: non-adverse drug event


Question: On discontinuation of the drug, serum CK concentrations returned to normal within eight days.

Answer: non-adverse drug event


Question: A 40-year-old man with relapsing-remitting multiple sclerosis (MS) developed primary central nervous system lymphoma (PCNSL) after having received 21 doses of natalizumab monotherapy.

Answer:
adverse drug event