Post-marketing withdrawal of 462 medicinal products because of adverse drug reactions: a systematic review of the world literature

Table 1 Levels of evidence used to justify post-marketing withdrawal of medicinal products

Level of evidence^a	Number (%) of withdrawals
Level of evidence^a	All marketed drugs (n = 462)	Marketed drugs launched since 1950 (n = 286)
Level 1: Systematic reviews	6 (1.3)	6 (2.1)
Level 2: Randomized studies	27 (5.8)	25 (8.7)
Level 3: Non-randomized studies	43 (9.3)	30 (10.5)
Level 4: Case reports	330 (71.4)	189 (66.1)
Level 5: Mechanism-based reasoning	56 (12.1)	36 (12.6)

^aBased on the Oxford Centre for Evidence-Based Medicine Levels of Evidence [13]. Level 1, Systematic review of randomized trials, systematic review of nested case-control studies; Level 2, Individual randomized trial or (exceptionally) observational study with dramatic effect; Level 3, Non-randomized controlled cohort/follow-up study (post-marketing surveillance); Level 4, Case-series, case-control, or historically controlled studies; Level 5, Mechanism-based reasoning

ISSN: 1741-7015