25

limit 24 to (addresses or bibliography or biography or comment or congresses or consensus development conference or consensus development conference, nih or dictionary or directory or duplicate publication or editorial or in vitro or interview or lectures or letter or news or newspaper article or “review”) [Limit not valid in CCTR; records were retained]

443

26

24 not 25

1463

27

randomized controlled trial.pt.

537352

28

controlled clinical trial.pt.

156124

29

randomized controlled trials/

62621

30

Random Allocation/

85834

31

Double-blind Method/

187602

32

Single-Blind Method/

21457

33

clinical trial.pt.

729105

34

Clinical Trials.mp. or exp Clinical Trials/

268451

35

exp Clinical Trial/

587643

36

(clinic$ adj25 trial$).tw.

218792

37

((singl$ or doubl$ or trebl$ or tripl$) adj (mask$ or blind$)).tw.

214271

38

Placebos/

46595

39

placebo$.tw.

225224

40

random$.tw.

736338

41

trial$.tw.

569938

42

(latin adj square).tw.

3500

43

Comparative Study.tw.

55680

44

exp Evaluation studies/

140739

45

Follow-Up Studies/

421249

46

Prospective Studies/

316292

47

(control$ or prospectiv$ or volunteer$).tw.

2441089