Background
Methods
Data sources and searches
Selection criteria
Data extraction, data synthesis and quality assessment
Results
General overview and methodological quality of included studies
First author year | from |
N
| Participants | Sampling | Response rate | Focus pure/impure placebo |
---|---|---|---|---|---|---|
Questionnaire-based quantitative surveys | ||||||
USA | 195 | Ph (various groups) | Convenience | 83% | Both | |
Goldberg 1979 [18] | USA | 102 | N (head nurses at 11 hospitals) | Local | 68% | Pure |
Goodwin 1979 [19] | USA | 60 | Ph (house officers) | Convenience | 100% | Mainly |
39 | N (hospital nurses) | Convenience | Unclear | pure | ||
27 | License practical nurses/medical aides | Convenience | Unclear | |||
Gray 1981 [20] | CAN | 70 | Ph (university hospital) | Convenience | 82%* | Pure |
230 | N (university hospital) | Convenience | ||||
35 | N (experienced hospital nurses) | Convenience | Unclear | |||
Lange 1981 [21] | GER | 81 | Ph, N, psychologists (no data for subgroups provided) | Convenience | Unclear | Pure |
Thomson 1982 [22] | NZ | 37 | Ph (GPs) | Local | 84% | Both |
Classen 1985 [23] | GER | 101 | Ph (setting unclear) | Convenience | Unclear | Both |
Saupe 1986 [24] | GER | 56 | N (at a psychiatric university hospital) | Convenience | 80% | Mainly pure |
Lynöe 1993 [26] | SWE | 94 | Ph (GPs or affiliated with university) | Local | 94% | Mainly |
83 | Pt (consecutive patients of three GPs) | Local | 83% | impure | ||
Ernst 1997 [27] | AUS | 263 | N (setting unclear) | Convenience | 58% | Both |
Berger 1999 [28] | USA | 74 | Medical interns at an university-affiliated hospital | Convenience | 83% | Pure |
Berthelot 2001 [29] | FRA | 300 | Pt (at a hospital rheumatology department) | Convenience | Unclear | Mainly |
100 | N (same hospital, various departments) | Convenience | Unclear | pure | ||
Hrobjartsson 2003 [30] | DEN | 502 | Ph (GPs, hospital, specialists in private practice) | Random | 65% | Both |
Nitzan 2005 [31] | ISR | 31 | Ph (senior hospital physicians) | Convenience | 76% | Mainly |
31 | N (head nurses from same hospitals) | Convenience | 100% | pure | ||
27 | Ph (family physicians) | Convenience | 68% | |||
Lim 2007 [32] | SIN | 402 | Medical students | Local | 36% | Pure |
Sherman 2007 [33] | USA | 231 | Ph (faculty members of 3 medical schools) | Local | 50% | Both |
Tilburt 2008 [34] | USA | 679 | Ph (internists and rheumatologists) | Random | 57% | Both |
Bernateck 2009 [35] | GER | 71 | Ph (university hospital) | Convenience | 80%* | Pure |
107 | N (university hospital) | Convenience | ||||
Chen 2009 [36] | NZ | 211 | Pt (in waiting rooms of two GP clinics) | Convenience | 48% | Mainly pure |
Fässler 2009 [37] | SWI | 233 | Ph (primary care) | Random | 48% | Both |
Substudies with prospective screening of medical records of hospital patients
| ||||||
Goodwin 1979 [19] | USA | 1900 | Pt (academic teaching hospital, treated during 6 months) | n.a. | Pure | |
Lange 1981 [21] | GER | 1725 | Pt (psychiatric hospital, all treated 1978) | n.a. | Pure | |
Qualitative studies
| ||||||
Comaroff 1976 [17] | UK | 47 | Ph (GPs) | Local | 92% | Mainly impure |
Schwartz 1989 [25] | USA | 72 | Ph (selected for often prescribing inefficient drugs) | n.a. | 51% | Impure |
Definitions of placebo
Frequency of placebo use
Author year | Setting | Type | Placebo use | Definition of use | Frequency or other additional information |
---|---|---|---|---|---|
Questionnaire- based quantitative surveys | |||||
Physicians
| |||||
Goodwin 1979 [19] | Hospital (house officers) | Pure* | 78% | Ever use for pain relief | |
Gray 1981 [20] | Hospital | Pure | 80% | Ever use | |
Classen 1985 [23] | Unclear | Pure | 60% | Use 'sometimes' | About 30% less than once a month |
Classen 1985 [23] | Unclear | Impure | 54% | Use 'sometimes' | |
Lynöe 1993 [26] | Unclear | Both | 99% | Ever use | None very often, 1% often, 4% rather often, 26% quite rarely, 68% rarely/very rarely |
Hrobjartsson 2003 [30] | General practice | Both | 86% | During the last year | 38% 1-10 times/year, 48% > 10 times/year |
Hrobjartsson 2003 [30] | Hospital | Both | 54% | During the last year | 44% 1-10 times/year, 10% > 10 times/year |
Hrobjartsson 2003 [30] | Specialist practice | Both | 41% | During the last year | 31% 1-10 times/year, 10% > 10 times/year |
Nitzan 2004 [31] | Hospital/family practice | Pure* | 53% | Use with a minimum frequency of once a year | 37% once a month or more often† |
Sherman 2007 [33] | Medical school faculty | Both | 45% | Ever use | 15% 1-10×, 8% > 10×, 22% not at all during last year |
Tilburt 2008 [34] | Specialist practice | Both | 80% | Ever use | 34% = once a month, 28% 2-3 times/month, 18% = once a week |
Bernateck 2009 [35] | Hospital | Pure | 52% | Use with a minimum frequency of once a year | 40% 1-2 times/year, 9% 1-2 times/month, 4% more often |
Fässler 2009 [37] | Primary care | Pure | 17% | Ever use | 93% once a month or less often |
Fässler 2009 [37] | Primary care | Impure | 57% | Ever use | |
Nurses
| |||||
Goldberg 1979 [18] | Hospital | Pure | 51% | Ever use | 44% with current use or use in the last 6 months |
Goodwin 1979 [19] | Hospital | Pure* | 82% | Ever use for pain relief | |
Gray 1981 (sample 1) [20] | Hospital | Pure | 80% | Ever use | |
Gray 1981 (sample 2) [20] | Hospital | Pure | 89% | At least once during the last 5 years | 63% during the last year |
Saupe 1985 [24] | Hospital | Pure | 100% | Ever use | 79% once or less per month, 21% more often |
Ernst 1997 [27] | Unclear | Pure | 57% | Ever use | |
Ernst 1997 [27] | Unclear | Both | 68% | Ever use | 12% during the last year |
Nitzan 2004 [31] | Hospital | Pure* | 71% | Use with a minimum frequency of once a year | 37% once a month or more often† |
Bernateck 2009 [35] | Hospital | Pure | 87% | Use with a minimum frequency of once a year | 45% 1-2 times/year, 33% 1-2 times/month, 9% more often |
Interns
| |||||
Berger 1999 [28] | Hospital | Pure | 16% | Ever witnessed use | Only 2% (1/47) had actually given a placebo |
Substudies with prospective screening of medical records of hospital patients
| |||||
Goodwin 1979 [19] | Hospital | Pure* | 0.3% | During 6 months (prospective) | |
Lange 1981 [21] | Psychiatric hospital | Pure | 5.1% | During 12 months (prospective) | 6.1% in women, 3.9% in men |
Indications and reasons for placebo use, placebo personality and beliefs in placebo effectiveness
First author year | Indications/reasons |
---|---|
Goldberg 1979 [18] | N: In 39 of 43 (91%) patient's pain was an indication. For 36 patients more than one reason was reported; in 51% anxiety; in 47% symptoms suspected not to be organic; in 33% in suspected drug abuse; in 24% as nothing else was helping; in 16% fear of iatrogenic addiction; in 7% concern for patient safety; in 37 of 43 patients receiving placebo (86%) anxiety and emotional problems were seen as prominent; 28% were considered less likeable; 30% more difficult than average; 81% were considered questionable or unreliable. |
Goodwin 1999 [19] | Ph/N: 87% of physicians and 97% of registered nurses who had used a placebo in the past had ordered it for a patient requiring more pain medication that thought necessary; 74% and 84% had ordered it in 'problem patients' |
Gray 1981 [20] | Ph/N: Conditions: 89% pain (45% patients with regular narcotic analgesia; 34% postoperative; 8% terminally ill); 9% anxiety. More than half of replies indicated that patients describing features such as manipulative, complaining, and histrionic behaviour usually received placebos. |
Lange 1981 [21] | Diagnoses in the 88 patients receiving placebo from the 1725 psychiatric patients surveyed: 27% schizophrenia and paranoid symptoms; 27% abuse; 19% depressive psychoses; 14% hysteric syndromes. Symptoms treated with placebo: 40% pain; 29% sleep problems; 8% agitation. Reasons for placebo application: most frequently to cope with a difficult situation and in frequently complaining or disliked patients. Further reasons: other interventions not successful; avoid substance abuse; patients desire for receiving drug treatment. |
Classen 1985 [23] | Ph: In patients who demand too many, too powerful or inadequate drugs (50%); psychosomatic complaints (42%); pain (36%); somatic disorders (7%). |
Saupe1986 [24] | N: 72% in demanding patients; 78% in patients with so called psychosomatic complaints; 67% requests for pain relief. |
Ernst 1997 [27] | N: Probably open-ended question (responses given by placebo users): 19% pain; 11% insomnia; 7% both; 8% anxiety; 5% addiction. |
Berger 1999 [28] | Medical interns: Likely to use a placebo in the following circumstances: Suspicion of factitious pain (48%); history of substance abuse (18%); psychiatric illness/psychological component (17%). |
Hrobjartsson 2003 [30] | Ph: 226 (45%) respondents provided examples: 90 used various placebos as for treating pain; 86 antibiotics for viral infections; 32 vitamins against fatigue; 28 various placebos for cough and chronic obstructive lung disease. Reported reasons (total sample): follow the wish of the patient and avoid conflicts with patients (70% GPs, 46% hospital clinicians, 42% private specialists); take advantage of the placebo effect (48%, 22%, 32%); avoid discontinuation of other prescriptions (40%, 27%, 18%); avoid telling patients that treatment possibilities are exhausted (36%, 11%, 17%). |
Nitzan 2004 [31] | Ph/N: Conditions: The medical conditions for which the placebos were used included anxiety, pain (including abdominal), agitation, vertigo, sleep problems, asthma, contractions in labour, withdrawal from recreational drugs, and angina pectoris (when the blood pressure was too low to allow for vasodilators). Reasons: 43% after 'unjustified' demand of medication; 38% to calm the patient; 38% as analgesic; 28% as diagnostic tool; 23% as adjunctive therapy; 17% for non-specific complaints; 15% to buy time before next regular dosage of medication; 11% to get patient to stop complaining. |
Sherman 2007 [33] | Ph: Among placebo users 18% used placebos to calm the patient; 18% as supplemental treatment; 15% after 'unjustified' demand for medication; 13% for non-specific symptoms; 11% after all treatment possibility were exhausted; 6% to control pain; 6% to get the patient stop complaining. |
Bernateck 2009 [35] | Ph: Conditions (responses given by placebo users): 76% (65% physicians, 81% nurses) for pain; 59% insomnia (40%, 66%); 12% depressive mood (19%, 10%). Reasons for placebo application: 64% (57%, 66%) patient's request for a drug; 37% (35%, 38%) for calming an anxious patient; 35% (24%, 40%) for reducing drug use; 20% (30%, 16%) for supporting other interventions; 18% (24%, 16%) to treat non-specific symptoms. |
Fässler 2009 [37] | Ph: 69% of placebo users report as motive 'to gain therapeutic advantage through the placebo effect'; 64% 'to offer a treatment to patients whose complaints and test results are not attributable to a certain disease'; 63% 'to conform with the requests of the patient'; 51% 'to offer treatment to difficult patients'; 44% 'to offer a treatment option to a patient with an incurable disease'; 37% 'in situations in which standard treatments may burden patients with side effects or are contraindicated'; 31% 'to avoid drug addiction'. |