Summary of findings 4. Quality of evidence.
| Author (year) | Randomization | Randomization unclear | Allocation concealment |
Allocation concealment unclear |
Allocation concealment Inadequate |
Blinding |
| Barneschi | computer | 1 envelope | Participants and outcome assessor= double blind | |||
| Bone | 1 | 1 | Double blind | |||
| Bonnardot (1987) | Table of numbers | 1 Opaque envelopes | Outcome assessor | |||
| Boysen (1989) | 1 | 1 | ||||
| Boysen (1990) | 1 | 1 | Outcome assessor | |||
| Cetin | Computer | 1 | Unclear | |||
| Collins | 1 | 1 | Unclear | |||
| Dahl | Random number list | 1 | Double blind | |||
| Edelman 2004 | Computer | 1 identical study syringes | Double blind | |||
| Edelman 2006 | computer | 1 identical study syringes | Double blind | |||
| Glantz | Permuted block technique | 1opaque sealed envelopes | ||||
| Hackett | 1 | 1 | Outcome assessor | |||
| Hall, G | 1 | 1 closed envelopes | Investigators blinded | |||
| Heath | 1 | 1 | Double blind | |||
| Hein 1999 | computer | 1 nurse drew envelope | Double blind | |||
| Hein 2001 | 1 | 1 envelope | Double blind | |||
| Jakobsson 1991 | computer | 1 envelope | Patient and outcome assessor = double blind | |||
| Jakobsson 1993 | computer | 1 envelope | Patient and outcome assessor = double blind | |||
| Jakobsson 1995 | computer | 1 envelope | Patient and outcome assessor = double blind | |||
| Jakobsson 1996 | computer | 1 sealed envelope | Double blind | |||
| Kan 2004 | computer | 1 opaque envelope | Double blind | |||
| Kan 2006 | computer | 1 sealed envelope | Double blind | |||
| Li 2003 | computer | 1 sealed envelope | Double blind | |||
| Li 2006 | computer | 1 sealed envelope | Double blind | |||
| Lindholm | 1 | 1 (identical looking ampoules delivered by pharmacy) | Anesthesiologist | |||
| Liu | 1 | 1 sealed opaque envelopes | Double blind | |||
| Marc | computer | 1 sealed opaque envelopes | ||||
| Ogg | 1 | 1 | Outcome assessor | |||
| Phair | computer | 1 opaque envelopes | NO BLINDING POSSIBLE | |||
| Raeder | computer | 1 sealed envelopes | Double blind | |||
| Rossi | 1 | 1 | Unclear | |||
| Shapiro | 1 | 1 | Unclear | |||
| Suprapto | 1 | 1 | Double blind | |||
| Wells 1989 | 1 | 1 | nurses, counselors, physicians and technicians | |||
| Wells 1992 | computer | 1 envelopes | Outcome assessor | |||
| Wiebe 1992 | computer | 1 The nurse drew up the syringes | Some phases double blind | |||
| Wiebe 1995 | computer | 1 opaque envelopes | Double blind for some phases | |||
| Wiebe 1996 | 1 | 1 assistant drew up the syringes | Double blind | |||
| Wiebe 2003 | computer | 1 opaque envelopes | Double blind | |||
| Wong 2002 | computer | 1 opaque envelopes | Double blind | |||
| TOTAL | 2 4 | 16 | 23 | 14 | 3 |