Characteristics of included studies
| Study | No. of “insiders” | No. of “outsiders” | Specialty | Intervention | Care setting |
|---|---|---|---|---|---|
| Akaza et al. 1995 (10) | 107 | 13 | Oncology | Vaccination | Hospital |
| Amar et al. 1997 (11) | 70 | 40 | Surgery | Anti-arrhythmic drugs | Hospital |
| Andersson et al. 2003 (12) | 24 | 8 | Family | Counselling | Home |
| Antman et al. 1985 (13) | 42 | 42 | Oncology | Chemotherapy | Cancer centre |
| Ashok et al. 2002 (14) | 229 | 45 | Ob/gyn | Abortion | Hospital |
| Bain et al. 2001 (15) | 36 | 62 | Anesthesia | Sedatives | Operating room |
| Bakker et al. 2000 (16) | 113 | 24 | Psychiatry | Counselling | Outpatient clinic |
| Balmukhanov et al. 1989 (17) | 108 | 287 | Oncology | Radiation | Hospital |
| Bannister et al. 2001 (18) | 202 | 38 | Anesthesia | Analgesics | Operation room |
| Bedi et al. 2000 (19) | 85 | 164 | Family | Counselling | Family clinic |
| Bell and Palma 2000 (20) | 59 | 56 | Ob/gyn | Exercise program | Unclear |
| Bhattacharya et al. 1998 (21) | 92 | 68 | Ob/gyn | Longer hospital stay | Hospital |
| Biasoli et al. 2008 (22) | 52 | 41 | Oncology | Chemotherapy | Hospital |
| Biederman et al. 1985 (23) | 24 | 18 | Psychiatry | Drugs | Inpatient |
| Bijker et al. 2002 (24) | 268 | 155 | Oncology | Excision | Unclear |
| Blichert-Toft et al. 1988 (25) | 619 | 136 | Oncology | Mastectomy | Surgical departments |
| Blumenthal et al. 1997 (26) | 66 | 38 | Cardiology | Exercise | Hospital |
| Boesen et al. 2007 (27) | 258 | 137 | Oncology | Psychoeducation | Outpatient clinic |
| Boezaart et al. 1998 (28) | 240 | 136 | Anesthesia | Drugs | Private hospital |
| Brinkhaus et al. 2008 (29) | 902 | 3 888 | Allergy | Acupuncture | Unclear |
| Caplan and Buchanan 1984 (30) | 29 | 46 | ID | Drugs | Hospital |
| CASS 1984 (31) | 779 | 1 309 | Cardiology | Surgery | Unclear |
| Chauhan et al. 1992 (32) | 38 | 15 | Ob/gyn | Amnio-infusion | Labour unit |
| Chesebro et al. 1983 (33) | 351 | 183 | Internal | Anticoagulant | Unclear |
| Chilvers et al. 2001 (34) | 98 | 207 | Family | Counselling v. drugs | Outpatient |
| Clagett et al. 1984 (35) | 29 | 28 | Surgery | Surgery | Unclear |
| Clapp et al. 1989 (36) | 115 | 85 | ID | Drugs | Pediatric hospital |
| Clemens et al. 1992 (37) | 20 744 | 21 943 | ID | Vaccine | Research centre |
| Cooper et al. 1997 (38) | – | – | Ob/gyn | Surgery | Hospital |
| Cowchock et al. 1992 (39) | 20 | 13 | Ob/gyn | Drugs | Unclear |
| Creutzig et al. 1993 (40) | 31 | 25 | Oncology | Radiation | Unclear |
| Dahan et al. 1986 (41) | – | – | Research design | Informed consent | Unclear |
| Dalal et al. 2007 (42) | 100 | 84 | Cardiology | Rehabilitation | Hospital, home |
| Decensi et al. 2003 (43) | 116 | 29 | Oncology | Drugs | Hospital |
| Detre et al. 1999 (44) | 343 | 299 | Cardiology | Surgery | Hospital |
| Eberhardt et al. 1996 (46) | 43 | 37 | Rheumatology | Drugs | Hospital |
| Edsmyr et al. 1978 (47) | 18 | 9 | Urology | Drugs | Unclear |
| Ekstein et al. 2002 (48) | 91 | 1 202 | Cardiology | Surgery | Hospital |
| Emery et al. 2003 (49) | 168 | 49 | Ob/gyn | Counselling | Hospital |
| Euler et al. 2005 (50) | 58 | 14 | Pediatrics | Diet | Unclear |
| Feit et al. 2000 (51) | 1 169 | 1 336 | Cardiology | Surgery | Hospital |
| Forbes and Collins 2000 (52) | 102 | 88 | Gastrointestinal | Drugs | Hospital |
| Franz et al. 1995 (53) | 179 | 62 | Nutrition | Diet | Unclear |
| Gall et al. 2007 (54) | 46 | 41 | Gastrointestinal | Follow-up | Hospital |
| Girón et al. 2010 (55) | 24 | 45 | Psychiatry | Family intervention | Mental health centre |
| Goodkin et al. 1987 (56) | 27 | 24 | Neurology | Drugs | Unclear |
| Gossop et al. 1986 (57) | 20 | 40 | Addiction | Inpatient treatment | Unclear |
| Grant et al. 2008 (58) | 299 | 375 | Gastrointestinal | Surgery | Hospital |
| Gunn et al. 2000 (59) | 122 | 308 | Pediatrics | Home support | Hospital |
| Helsing et al. 1998 (60) | 47 | 97 | Oncology | Supportive care | Unclear |
| Henriksson and Edhaq 1986 (61) | 91 | 9 | Urology | Surgery | Unclear |
| Heuss et al. 2004 (62) | 74 | 40 | Gastrointestinal | Sedation | Hospital |
| Hoh et al. 1998 (63) | 13 | 39 | Nutrition | Diet | Hospital |
| Howard et al. 2009 (64) | 44 | 28 | Psychiatry | Crisis houses | Hospital |
| Howie et al. 1997 (65) | 77 | 63 | Ob/gyn | Abortion | Hospital |
| Jena et al. 2008 (66) | 2 792 | 10 410 | Alternative | Acupuncture | Unclear |
| Jensen et al. 2003 (67) | 897 | 294 | Geriatrics | Hormones | Hospital |
| Kane 1988 (68) | 59 | 116 | Orthopedics | Bone growth stimulator | Unclear |
| Karande et al. 1999 (69) | 63 | 57 | Ob/gyn | IVF | Infertility clinic |
| Kayser et al. 2008 (70) | 31 | 44 | Travel | Drugs | Unclear |
| Kendrick et al. 2001 (71) | 394 | 50 | Technology | Radiography | General practice or hospital |
| Kieler et al. 1998 (72) | 526 | 4 801 | Ob/gyn | Ultrasonography | Antenatal care clinic |
| King et al. 2000 (73) | 165 | 106 | Psychiatry | Counselling | Unclear |
| Kirke et al. 1992 (74) | 351 | 106 | Ob/gyn | Folic acid | Unclear |
| Koch-Henriksen et al. 2006 (75) | 224 | 74 | Neurology | Drugs | Unclear |
| Lansky and Vance 1983 (76) | 55 | 59 | Psychology | Diet and exercise | Unclear |
| Lichtenberg et al. 2008 (77) | 217 | 153 | Psychiatry | Case management | Unclear |
| Lidbrink et al. 1995 (78) | 20 000 | 7 785 | Oncology | Mammography | Unclear |
| Link et al. 1991 (79) | 36 | 77 | Oncology | Drugs | Unclear |
| Liu et al. 2009 (80) | 169 | 163 | Alternative | Salvia | Delivery room |
| Lock et al. 2010 (81) | 40 | 303 | Surgery | Tonsillectomy | ENT department |
| Loeffler et al. 1997 (45) | 100 | 21 | Oncology | Radiotherapy | Hospital |
| Luby et al. 2002 (82) | 162 | 79 | ID | Antibacterial soap | Home |
| Macdonald et al. 2007 (83) | 5 | 48 | Nephrology | Drugs | Unclear |
| MacLennan et al. 1985 (84) | 96 | 73 | Ob/gyn | Relaxin | IVF clinic |
| MacMillan et al. 1986 (85) | 107 | 49 | Psychiatry | Drugs | Unclear |
| Mahon et al. 1996 (86) | – | – | Respirology | Drugs | Hospital |
| Mahon et al. 1999 (87) | – | – | Respirology | Drugs | Primary care |
| Marcinczyk et al. 1997 (88) | 54 | 29 | Vascular surgery | Endarterectomy | Hospital |
| Martin 1994 (89) | 46 | 54 | Gastrointestinal | Antacid | Hospital |
| Martínez-Amenos et al. 1990 (90) | 589 | 133 | Family | Education | Primary care |
| Masood et al. 2002 (91) | 96 | 14 | Urology | Nitrous oxide – oxygen | Urology department |
| Matilla et al. 2003 (92) | 137 | 166 | ENT | Surgery | Study clinic |
| Mayo Group 1992 (93) | 71 | 87 | Vascular surgery | Endarterectomy | Unclear |
| McCaughey et al. 1998 (94) | 19 | 13 | Pediatrics | Hormone | Hospital |
| McKay et al. 1998 (95) | 101 | 51 | Psychology | Day hospital | Hospital |
| McKay et al. 1995 (96) | 40 | 80 | Psychology | Day hospital | Addiction recovery unit |
| Melchart et al. 2002 (97) | 26 | 80 | Alternative | Acupuncture | Hospital |
| Moertel et al. 1984 (98) | 62 | 10 | Oncology | Chemo + radiation | Hospital |
| Mori et al. 2006 (99) | 712 | 158 | Gastrointestinal | Endoscopy | Hospital |
| Morrison et al. 2002 (100) | 454 | 302 | Cardiology | Surgery | Hospital |
| Nagel et al. 1998 (101) | 115 | 95 | Ob/gyn | Amniocentesis | Hospital |
| Neldam et al. 1986 (102) | 978 | 349 | Ob/gyn | Fetal heart monitor | Hospital |
| Nicolaides et al. 1994 (103) | 488 | 812 | Ob/gyn | Chorionic villus sampling | Research centre |
| Ogden et al. 2004 (104) | 285 | 47 | Orthopedics | Shock wave treatment | Unclear |
| Palmon et al. 1996 (105) | 50 | 10 | Critical care | Carbon dioxide monitor | Neuroradiology centre |
| Panagopoulou et al. 2009 (106) | 148 | 66 | Psychology | Diary writing | Clinic |
| Paradise et al. 1984 (107) | 42 | 28 | Surgery | Tonsillectomy | Hospital |
| Petersen et al. 2007 (108) | 79 | 33 | Orthopedics | Hip replacement | Hospital |
| Raistrick et al. 2005 (109) | 174 | 225 | Addiction | Drugs | Addiction recovery unit |
| Reddihough et al. 1998 (110) | 19 | 22 | Physiotherapy | Education | Unclear |
| Rigg et al. 2000 (111) | 455 | 237 | Anesthesia | Analgesia | Hospital |
| Rørbye et al. 2005 (112) | 105 | 727 | Ob/gyn | Abortion | Hospital |
| Rosen et al. 1987 (113) | 98 | 44 | Anesthesia | Nitrous oxide | Hospital |
| Salisbury et al. 2002 (114) | 253 | 129 | Family | School-based clinics | Unclear |
| Sesso et al. 2002 (115) | 22 071 | 11 152 | Cardiology | ASA | Unclear |
| Shain et al. 1989 (116) | 155 | 98 | Ob/gyn | Contraception | Unclear |
| Smith and Arnesen 1990 (117) | 1 214 | 270 | Internal | Warfarin | Cardiology centre |
| Smuts et al. 2003 (118) | 16 | 37 | Pediatrics | Diet | Unclear |
| Stecksén-Blicks et al. 2008 (119) | 115 | 64 | Dentistry | Lozenges | Clinic |
| Stern et al. 2003 (120) | 555 | 1 788 | Ob/gyn | Anticoagulants | Hospital |
| Stith et al. 2004 (121) | 19 | 4 | Psychology | Couple therapy | Unclear |
| Stockton and Mengersen 2009 (122) | 57 | 21 | Rehab | Physiotherapy | Hospital |
| Strandberg et al. 1995 (123) | 910 | 489 | Cardiology | Health checks | Hospital |
| Suherman et al. 1999 (124) | 83 | 29 | Ob/gyn | Contraception | Unclear |
| Sullivan et al. 1982 (125) | 144 | 25 | Oncology | Radiotherapy | Unclear |
| Sundar et al. 2008 (126) | 136 | 45 | ID | Drugs | Inpatient unit |
| Taddio et al. 2006 (127) | 98 | 20 | Pediatrics | Analgesics | Hospital |
| Tanai et al. 2009 (128) | 100 | 19 | Oncology | Drugs | Hospital |
| Tanaka et al. 1994 (129) | 30 | 10 | Anesthesia | Drugs | Unclear |
| Taplin et al. 1986 (130) | 63 | 30 | Dermatology | Permethrin cream | Unclear |
| Tenenbaum et al. 2002 (131) | 3 122 | 380 | Cardiology | Drugs | Hospital |
| Toprak et al. 2005 (132) | 30 | 15 | Ob/gyn | Hormone replacement | Clinic |
| Underwood et al. 2008 (133) | 187 | 271 | Geriatrics | Ibuprofen | Primary care |
| Urban et al. 1999 (134) | 55 | 24 | Cardiology | Early revascularization | Unclear |
| Van et al. 2009 (136) | 40 | 45 | Psychiatry | Therapy | Unclear |
| van Bergen et al. 1995 (135) | 350 | 587 | Cardiology | Anticoagulant | Centre |
| Verdonck et al. 1995 (137) | 69 | 37 | Oncology | Chemotherapy | Unclear |
| Vind et al. 2009 (138) | 256 | 297 | Geriatrics | Fall prevention | Unclear |
| Walker et al. 1986 (139) | 98 | 37 | Surgery | Antibiotics | Unclear |
| Wallage et al. 2003 (140) | 178 | 28 | Ob/gyn | Anesthesia | Hospital |
| Watzke et al. 2010 (141) | 180 | 97 | Psychiatry | Counselling | Inpatient unit |
| Welt et al. 1981 (142) | 23 | 40 | Ob/gyn | Drugs | Unclear |
| West et al. 2005 (143) | 86 | 322 | Critical care | Magnesium sulphate | Unclear |
| Wetzner et al. 1979 (144) | 34 | 64 | Radiology | Contrast | Unclear |
| Wieringa-de Waard et al. 2002 (146) | 122 | 305 | Ob/gyn | Evacuation | Clinic |
| Williford et al. 1993 (147) | 395 | 199 | Nutrition | Diet | Unclear |
| Witt et al. 2006a (148) | 543 | 2 481 | Alternative | Acupuncture | Unclear |
| Witt et al. 2006b (149) | 3 036 | 4 686 | Alternative | Acupuncture | Unclear |
| Witt et al. 2006c (150) | 2 518 | 3 901 | Alternative | Acupuncture | Unclear |
| Witt et al. 2008 (151) | 57 | 21 | Alternative | Acupuncture | Unclear |
| Woodhouse et al. 1995 (152) | 194 | 145 | Cardiology | Adrenaline dose | Hospital |
| World Health Organization 1988 (145) | 40 | 32 | Ob/gyn | Contraception | Unclear |
| Wyse et al. 1991 (153) | 1 672 | 318 | Cardiology | Anti-arrhythmic drugs | Unclear |
| Yamamoto et al. 1992 (154) | 31 | 92 | Gastrointestinal | Esophageal dilator | Unclear |
| Yamani et al. 2005 (155) | 23 | 33 | ID | Vaccine | Unclear |
| Yersin et al. 1996 (156) | 20 | 10 | Addiction | Counselling | Unclear |
Note: ASA = acetylsalicylic acid, CASS = Coronary Artery Surgery Study, chemo = chemotherapy, ENT = ear, nose and throat, Family = family medicine, ID = infectious diseases, “insider” = patient receiving treatment within a randomized controlled trial, IVF = in vitro fertilization, Ob/gyn = obstetrics and gynecology, “outsider” = patient receiving treatment via routine clinical care outside the randomized controlled trial.