Figure 1

Study retrieval flow diagram

Table 1

Search		Results
Medline (set)
001	creutzfeldt-jakob syndrome/	723
002	creutzfeldt.tw.	584
003	cjd.tw.	265
004	or/1-3	838
005	risk.tw.	85 952
006	exp cohort studies/	95 306
007	exp risk/	63 870
008	(odd$ and ratio$).tw.	8121
009	(relative and risk).tw.	8063
010	(case and control).tw.	11 035
011	exp case-control studies/	57 864
012	or/5-11	226 592
013	`4.mp. and 12 [mp=title, abstract, registry number word, mesh subject heading]	34 138
014	4 and 12	175
015	limit 14 to review	50
016	14 not 15	125
017	limit 16 to (comment or editorial)	25
018	16 not 17	100
019	limit 18 to human	96
Embase
1	exp Creutzfeldt jakob disease/	1439
2	creutzfeld.tw.	59
3	cjd.tw.	454
4	or/1-3	1481
5	risk.tw.	176 519
6	exp cohort studies/	4947
7	exp risk/	111 690
8	(odd$ and ratio$).tw.	12 791
9	(relative and risk).tw.	15 991
10	(case and control).tw.	22 898
11	exp Case control study/	3735
12	or/5-11	240 430
13	4 and 12	180
14	limit 13 to review	36
15	13 not 14	144
16	limit 15 to editorial	12
17	15 not 16	132
18	limit 17 to human	112