Table 2.

Case study results

	Original search strategy			Filtered search strategy
	No. of search hits retrieved	No. of included references retrieved	NNR	No. of search hits retrieved	No. of included references retrieved	Recall of included references found by original strategy	NNR
NG103: Evidence review 3: increasing uptake in clinical risk groups
MEDLINE	5,635	22	256	5,108	22	100%	232
Embase	9,707	26	373	8,884	26	100%	341
NG140: Evidence review P: contraception after abortion
MEDLINE	620	16	38	443	16	100%	27
Embase	1619	16	101	1216	16	100%	76
NG146: Evidence review C: facilitating the return to work of employees on long-term sickness absence and reducing risk of recurrence
MEDLINE	13,902	22	631	13,022	22	100%	591
Embase	20,775	21	989	19,443	21	100%	925
NG103, NG140, and NG146 combined
MEDLINE	20,157	60	336	18,573	60	100%	309
Embase	32,101	63	510	29,543	63	100%	469