Table 6.

Overview of the observational study search filter's performance in PubMed and Embase

	PubMed
	Relevant records in a retrospective search (= gold standard, a+b): 84	Irrelevant records in a retrospective search (c+d): 10,983
Records retrieved with search filter (a+c): 3,604	True positives a): 71	False positives (c): 3,533
Records not retrieved with search filter: 7,463	False negatives (b): 13	True negatives (d): 7,450
	Embase
	Relevant records in a retrospective search (= gold standard, a+b): 77	Irrelevant records in a retrospective search (c+d): 17,019
Records retrieved with search filter (a+c): 9,078	True positives (a): 74	False positives (c): 9,004
Records not retrieved with search filter: 8,018	False negatives (b): 3	True negatives (d): 8,015