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PubMed2005

Reconsidering the role of personality in placebo effects: dispositional optimism, situational expectations, and the placebo response.

OBJECTIVE: Prior investigations have failed to find reliable personality differences in placebo responding. The present study tests the hypothesis that personality and situational variables interact to determine placebo responding. METHODS: Optimists and pessimists were randomly assigned to one of three conditions. In the first condition, the participants were told that they were to ingest a pill that would make them feel unpleasant (deceptive-expectation group). In the second condition, the participants were told that they were to ingest a pill that would make them feel either unpleasant or was an inactive substance (conditional-expectation group). Finally, a third group was told they were to ingest a pill that was inactive (control group). RESULTS: Pessimists were more likely than optimists to follow a negative-placebo expectation when given a deceptive expectation, but not when given a conditional expectation. CONCLUSION: The personality variable optimism-pessimism relates to placebo responding when individuals are given a deceptive but not a conditional expectation. This suggests that personality and situational variables interact to determine placebo responding.

Adult↗

PubMed2005

[Placebo and placebo effect].

The word placebo appeared for the first time in an English medical dictionary in 1785. In French, it appeared much latter in 1958. This word defines an experimental tool used for rigourous evaluation of a specific effect of pharmacological treatment and the non specific effect of any therapy. The placebo effect is the strictly psychological or psychophysiological effect of a placebo. The two principal components of placebo effect as a pain killer, which has been extensively studied in this field, are positive expectancies of both the patient and the physician. Although the mechanisms of action of placebo effect are not well understood, results of several recent works are particularly interesting.

Humans↗

PubMed1996

Are more antiemetic trials with a placebo necessary? Report of patient data from randomized trials of placebo antiemetics with cisplatin.

BACKGROUND: Because of the predictability of significant emesis after its use, cisplatin serves as the standard emetic stimulus for trials of antiemetic drugs. To define better the incidence, severity, and pattern of emesis that follows cisplatin, facilitate the testing of new agents, and obviate the need for further placebo-controlled trials for this indication, individual patient data were compiled from completed studies with placebo antiemetics and cisplatin. METHODS: The time and number of emetic episodes during the 24 hours after cisplatin were obtained for 48 patients given a placebo antiemetic. Each was treated as part of a randomized, double-blind trial reported between 1981 and 1990. Emesis after antiemetic "rescue" therapy was also assessed. RESULTS: Emesis occurred in 47 of 48 patients (98% observed rate, 95% confidence interval, 89-99%). The median number of emetic episodes during the 24 hours after cisplatin was 6. Emesis continued after rescue in 77% of patients. CONCLUSIONS: Cisplatin caused severe emesis that persisted despite rescue in placebo-treated patients. Using the data presented, any therapy preventing acute emesis in 8 or more of the 48 individuals receiving cisplatin > 50 mg/m2 was an active antiemetic (P = 0.05). The four trials discussed here documented the antiemetic effectiveness of granisetron, metoclopramide, and ondansetron. The placebo-treated patients studied can serve as a control group for testing new therapies. Because of the certainty of severe emesis after cisplatin, and the availability both of these data and several proven drugs for this condition, prospective comparisons of antiemetics should employ active control medications.

Adult↗

PubMed1979

Placebo response, placebo effect, and two attributes.

Two putative predictors of placebo response were studied in three samples of psychiatric outpatients. Two groups, 73 university medical center patients and 56 college health service patients, underwent 1 week of placebo treatment. A quasi-control group of 112 patients receiving no medication waited about 1 week before beginning psychotherapy. One attribute, acquiescence or traditionalism, predicted placebo response, thereby replicating prior findings. Acquiescence was unrelated to change in controls indicating that it may represent a correlate of true placebo effect under some conditions. Additional findings suggested qualifications as to the generality of the relationship. The second attribute, autonomic awareness, was associated with change in all three samples. It appeared to predict nonspecific improvement unrelated to placebo probably due to its relationship to intensity of somatization.

Adult↗

PubMed1979

[On circadian variations of the placebo effect on the pain threshold of healthy teeth: Contribution to a physiology of placebo effects (author's transl)].

Placebo doses can influence the pain threshold of healthy teeth according to the label. Systematic longitudinal researches over the day with measuring the utilization time of cold stimulus on healthy front teeth demonstrate that the placebo effect is subject to significant circadian variations. During daytime a pseudo-analgesic causes a stronger and steeper onset of increase of the tooth pain threshold than during the night, when the pain threshold is influenced only minimal or even inverse. The placebo effect can come up to 40% of the pain threshold increase caused by a usual analgesic; this portion, however, is as well subject to high circadian variations. The extent of the placebo effect corresponds to the order of magnitude of the spontaneous circadian variations of pain threshold and correlates positively to it. These correlations are considered as indicating that those vegetative mechanisms causing the circadian variations of the pain threshold are equally involved in affecting the placebo actions.

Circadian Rhythm↗

PubMed1992

A double-blind, placebo-controlled study of the safety and efficacy of ipratropium bromide nasal spray versus placebo in patients with the common cold.

Ipratropium bromide (IB) has been found to reduce secretions in the upper respiratory tract; this is accomplished through competitive inhibition of acetylcholine at muscarinic receptors that control rhinorrhea production. This study compared the safety and efficacy of IB with placebo in the symptomatic relief of rhinorrhea in patients with the common cold. Human subjects with symptoms of a common cold, primarily rhinorrhea, were enrolled and treated with either IB (84 micrograms/nostril) or placebo; each was administered as two sprays per nostril, four times a day, for 4 days. Primary efficacy analyses were in-clinic measurements of nasal discharge weights over a 3-hour period after administration on days 1 and 2 and assessment of rhinorrhea symptoms by use of a subjective patient-completed visual analog rating scale. IB significantly reduced rhinorrhea an average of 18% over placebo for days 1 and 2 (p = 0.01). Visual analog scale scores showed an average improvement in rhinorrhea of 22% over placebo (p = 0.001). When patients with relatively minor rhinorrhea (baseline weight of nasal discharge < or = 1.0 gm) were excluded, IB produced an average reduction in nasal discharge of 23% over placebo for days 1 and 2 (p = 0.003).

Adult↗

PubMed2003

The placebo needle, is it a valid and convincing placebo for use in acupuncture trials? A randomised, single-blind, cross-over pilot trial.

The issue of what constitutes an effective and realistic acupuncture placebo control has been a continuing problem for acupuncture research. In order to provide an effective placebo, the control procedure must be convincing, visible and should mimic, in all respects, apart from a physiological effect, the real active treatment. The 'Streitberger' needle might fulfil these criteria and this paper reports on a validation study. This was a single-blind, randomised, cross-over pilot study. Patients were drawn from the orthopaedic hip and knee, joint replacement waiting list. Intervention consisted of either 2 weeks of treatment with real acupuncture followed by 2 weeks on placebo, or vice versa. The prime outcome was a needle sensation questionnaire and there was a range of secondary outcomes. Thirty-seven patients were randomised and completed treatment. Groups were well balanced at baseline. No significant differences between groups or needle types were found for any of the sensations measured. Most patients were unable to discriminate between the needles by penetration; however, nearly 40% were able to detect a difference in treatment type between needles. No major differences in outcome between real and placebo needling could be found. The fact that nearly 40% of subjects did not find that the two interventions were similar, however, raises some concerns with regard to the wholesale adoption of this instrument as a standard acupuncture placebo. Further work on inter-tester reliability and standardisation of technique is highly recommended before we can be confident about using this needle in further studies.

Acupuncture Therapy↗

PubMed1998

A placebo controlled investigation of the effects of tryptophan or placebo on subjective and objective measures of fatigue.

OBJECTIVE: To examine the effect of L-tryptophan administration on subjective and objective measures of fatigue in healthy volunteers. SUBJECTS: Six healthy volunteers (4M:2F) were recruited from staff and students at the College. SETTING: Department of Human Nutrition, St. Bartholomews and the Royal London School of Medicine and Dentistry. DESIGN: Subjects were tested for central and peripheral fatigue using a visual analogue scale, flicker fusion frequency, grip strength, reaction time and wrist ergometry. In addition, plasma free tryptophan concentrations and Trp:LNAA ratio were determined. Measurements were made before, and at 1, 2, 3 and 4 h after drinking one of two test drinks. The drinks were of either caffeine free diet Coca-Cola (placebo) or caffeine free diet Coca-Cola plus L-tryptophan (30 mg/kg: active drink). Each of the six subjects was tested after placebo and active drink with a one week washout period between test days. RESULTS: Subjective fatigue was significantly increased following tryptophan compared to placebo (P < 0.002), and objective measures of central fatigue were significantly increased by tryptophan compared to placebo (flicker fusion frequency: P < 0.001; reaction time P < 0.001). No significant changes in grip strength were found following tryptophan compared to placebo, but a significant increase in ergometric work output was seen (P < 0.001). CONCLUSION: Tryptophan ingestion in the quantity 30 mg/kg leads to increased subjective and central fatigue. Increases in work output observed following tryptophan may be as a result of a reduced perception of discomfort during ergometry.

Adult↗

PubMedDate not supplied

Extracorporeal shockwave therapy versus placebo for the treatment of chronic proximal plantar fasciitis: results of a randomized, placebo-controlled, double-blinded, multicenter intervention trial.

Extracorporeal shockwave therapy (ESWT) has demonstrated efficacy in the treatment of recalcitrant proximal plantar fasciitis. The objective of this investigation was to compare the outcomes of participants treated with a new ESWT device with those treated with placebo. A total of 172 volunteer participants were randomized in a 2:1 active-to-placebo ratio in this prospective, double-blind, multicenter trial conducted between October 2003 and December 2004. ESWT (n=115) or placebo control (n=57) was administered on a single occasion without local or systemic anesthesia or sedation, after which follow-up was undertaken. The primary outcomes were the blind assessor's objective, and the participant's subjective assessments of heel pain during the first 3 months of follow-up. Participants were also followed up to 1 year to identify any adverse outcomes that may have been related to the shockwave device. On the visual analog scale, the blind assessor's objective assessment of heel pain displayed a mean reduction of 2.51 in the shockwave group and 1.57 in the placebo group; this difference was statistically significant (P=.045). On the visual analog scale, the participant's self-assessment of heel pain displayed a mean reduction of 3.39 in the shockwave group and 1.78 in the placebo group; this difference was statistically significant (P<.001). No serious adverse events were observed at any time. It was concluded that ESWT was both efficacious and safe for participants with chronic proximal plantar fasciitis that had been unresponsive to exhaustive conservative treatment.

Chronic Disease↗

PubMed2004

Natural course and placebo response in short-term, placebo-controlled studies in major depression: a meta-analysis of published and non-published studies.

BACKGROUND: This study was conducted to investigate the role of natural course of a major depressive episode in short-term, placebo-controlled studies. METHODS: We analyzed for sustained response all placebo arms and tricyclic arms from all randomized three-arm studies that were conducted in patients with a major depressive episode and were submitted to the Medicine Evaluation Board (1979-1991). The Medicine Evaluation Board is the regulatory authority of the Netherlands. A responder was defined as a patient with at least 50% improvement on the Hamilton Depression Rating Scale as compared to baseline score. A study responder was defined as a patient meeting response criteria at endpoint (Last Observation Carried Forward). A sustained responder was defined as a patient who, after becoming responder, remained a responder until the end of the study. RESULTS: The ITT population incorporated 1989 patients in the tricyclic arm and 2042 patients in the placebo arm. There was a statistically significant difference for study responders: 39.3% in the tricyclic treatment group and 27.9% in the placebo group (difference 11.4; CI (95%): 8.5% 14.3%). However, no significant differences in sustained response patterns were found, with the exception of a significantly higher sustained response rate for initial responders at week 4. CONCLUSIONS: While efficacy of tricyclic antidepressants was confirmed in this meta-analysis, the sustained response patterns of active treatment and placebo did not differ substantially, suggesting that many of the patients included in the studies were close to, or at the end of, their episode.

Antidepressive Agents, Tricyclic↗

PubMed2004

AACAP 2002 research forum: placebo and alternatives to placebo in randomized controlled trials in pediatric psychopharmacology.

OBJECTIVE: The use of placebo in the pediatric age group has come under increasing scrutiny. At the 2002 Annual Meeting of the American Academy of Child and Adolescent Psychiatry, the Academy's Workgroup on Research conducted a research forum. The purpose was to identify challenges and their solutions regarding the use of placebo in randomized controlled trials in pediatric psychopharmacology. METHOD: Workgroups focused on problems and solutions in five areas: ethics and human subjects, research design and statistics, partnering with consumers, U.S. Food and Drug Administration and pharmaceutical industry perspectives, and psychosocial treatments. RESULTS: In many but not all circumstances, inclusion of a placebo control is essential to meet the scientific goals of treatment outcome research. Innovative research designs; involvement of consumers in planning and implementing research; flexibility by industry, academia, the National Institutes of Health, and regulatory agencies acting in partnership; and concomitant use of evidence-based psychosocial services can and should assist in making placebo-controlled trials acceptable. CONCLUSIONS: Properly designed placebo-controlled trials remain necessary, ethical, and feasible.

Adolescent↗

PubMed2005

[The relationship between the placebo effect and spontaneous improvement in research on antidepressants. Are placebos powerless?].

Clinical trials of antidepressant medications have generally found large changes in groups given a placebo, which may be due to either spontaneous remission or a true placebo effect. This paper reviews the evidence for a true placebo effect in the treatment of unipolar depressed outpatients. Although there is no evidence from experimental studies, a rather substantial amount of circumstantial evidence indicates a true placebo effect. This article raises the question of whether it is meaningful to require experimental evidence for a loose and unspecified concept involving varying components such as placebo.

Antidepressive Agents↗

PubMed1982

Placebos and general practice: attitudes to, and the use of, the placebo effect.

The present study surveyed Dunedin general practitioners to determine whether they would deliberately use placebo treatments, under what conditions they would do so, their basic understanding of the placebo effect, and their perception of their use of placebos relative to that of their colleagues. Results indicated that almost all GPS surveyed would deliberately use a placebo treatment under some circumstances. However, there was a clear and statistically significant tendency to understate their use relative to that of their colleagues. It was also clear that a significant number of those surveyed felt placebo treatments to be more appropriate for "imaginary illnesses". Results are discussed in comparison with overseas studies and in regard to their implications for medical training.

Attitude↗

PubMed2004

Randomised, double blind, placebo controlled trial of interferon, ribavirin, and amantadine versus interferon, ribavirin, and placebo in treatment naïve patients with chronic hepatitis C.

BACKGROUND AND AIM: In this study, we compared the efficacy of triple therapy (interferon alfa, ribavirin, and amantadine) with standard therapy (interferon alfa and ribavirin) in treatment naïve patients with chronic hepatitis C virus (HCV). METHODS: In this prospective, randomised, double blind, placebo controlled, multicentre study, 85 patients (amantadine group) received a three drug regimen of interferon alfa-2b 3 million units three times per week, ribavirin 1000-1200 mg daily in divided doses, and amantadine 100 mg twice daily, and 86 patients (placebo group) received interferon alfa-2b, ribavirin, and identical placebo. Treatment was discontinued at 24 weeks if patients had detectable HCV RNA by polymerase chain reaction (PCR). All patients were followed for 24 weeks after completion of treatment. The primary end point was undetectable HCV-RNA by PCR at 24 weeks (sustained viral clearance) after completion of treatment. RESULTS: At the end of treatment, HCV RNA clearance was seen in 32.9% of the amantadine group and 38.4% of the placebo group (p=0.3). Sustained virological response was seen in 24.7% of the amantadine group and in 27.9% of the placebo group by intention to treat analysis; response rate was 30.4% and 34.8%, respectively, in those who completed 24 weeks of treatment. Poor response was seen in both groups among cirrhotics, African-Americans, genotype 1, and those with a higher viral load. By multivariate analysis, genotype 1, high viral load, and low serum albumin were the only predictors of poor response. Addition of amantadine to the standard regimen did not result in any unexpected side effects. CONCLUSION: Response to triple therapy of interferon alfa, ribavirin, and amantadine was similar to standard therapy of interferon alfa and ribavirin. Our results suggest that amantadine has no role in the management of HCV.

Adult↗

PubMed2002

The PLACORHEN study: a double-blind, placebo-controlled, randomized radionuclide study with (186)Re-etidronate in hormone-resistant prostate cancer patients with painful bone metastases. Placebo Controlled Rhenium Study.

UNLABELLED: (186)Re-1,1-hydroxyethylidene diphosphonate (etidronate) can be used for the palliative treatment of metastatic bone pain. A randomized, placebo-controlled study using (186)Re-etidronate was conducted on end-stage prostate cancer patients with metastatic bone pain. METHODS: Pain relief was assessed using an electronic diary containing questions reflecting the multidimensional character of chronic pain. The diary was marked twice daily for a maximum of 14 wk (2 wk before and 12 wk after the injection). Pain response was determined using a specific decision rule in which pain intensity, medication index, and daily activities were the core determinants. A positive response day was defined as a day on which pain intensity was reduced > or = 25% compared with baseline values, while medication index and daily activities were at least constant, or on which pain intensity was reduced < 25% and medication index or daily activities improved > or = 25%, without worsening of the remaining factor. The total response (%) was defined as the number of positive response days divided by the number of days of follow-up. RESULTS: Of the 111 included patients, 79 were evaluable (43 (186)Re-etidronate, 36 placebo). Thirty-two patients were excluded from the analysis because of incomplete datasets. The total response of the patients treated with (186)Re-etidronate varied from 0% to 96% (mean, 27%, or 23/84 d). In the placebo group, the total response varied from 0% to 80% (mean, 13%, or 11/84 d; Mann-Whitney U test, P < 0.05). The number of patients who requested radiotherapy was higher in the placebo group (67%) than in the (186)Re-etidronate group (44%) (relative risk, 1.51; Fisher's exact test, P = 0.069). CONCLUSION: This randomized controlled trial confirmed that, compared with placebo, (186)Re-etidronate resulted in a significantly longer pain response in the treatment of bone pain from metastasized prostate cancer.

Aged↗

PubMed2002

Unexpected benefit of sorbitol placebo in Mg intervention study of premenstrual symptoms: implications for choice of placebo in RCTs.

We carried out a randomized, double-blind, crossover study of 85 women, designed to investigate the dose-response of daily Mg supplementation on premenstrual symptoms. Each woman took one of four treatments: Mg (200, 350 or 500 mg/day) or sorbitol (placebo) for 2 months. This was followed by a washout of 1 month, and then each woman received one of the three remaining treatments for a further 2 months. Unexpectedly, sorbitol (1305 mg) reduced anxiety-related and total premenstrual symptoms after 2 months compared with Mg treatments (P<0.001 and P<0.001, respectively). We conclude that low-dose sorbitol reduces premenstrual symptoms beyond that expected of a placebo. After 2 months of treatment, sorbitol also reduced urinary Mg excretion compared to baseline (no intervention) and Mg treatments (P=0.005). A follow-up study on 17 healthy volunteers confirmed lack of effect on urinary Mg output of a similar sorbitol intervention regime compared with either baseline or cellulose placebo. It appears that sorbitol may influence Mg homeostasis in women suffering premenstrual symptoms, but not in healthy individuals. Implications for placebo choice in RCTs are discussed.

Adult↗

PubMed2004

Is the placebo powerless? Update of a systematic review with 52 new randomized trials comparing placebo with no treatment.

BACKGROUND: It is widely believed that placebo interventions induce powerful effects. We could not confirm this in a systematic review of 114 randomized trials that compared placebo-treated with untreated patients. AIM: To study whether a new sample of trials would reproduce our earlier findings, and to update the review. METHODS: Systematic review of trials that were published since our last search (or not previously identified), and of all available trials. RESULTS: Data was available in 42 out of 52 new trials (3212 patients). The results were similar to our previous findings. The updated review summarizes data from 156 trials (11 737 patients). We found no statistically significant pooled effect in 38 trials with binary outcomes, relative risk 0.95 (95% confidence interval 0.89-1.01). The effect on continuous outcomes decreased with increasing sample size, and there was considerable variation in effect also between large trials; the effect estimates should therefore be interpreted cautiously. If this bias is disregarded, the pooled standardized mean difference in 118 trials with continuous outcomes was -0.24 (-0.31 to -0.17). For trials with patient-reported outcomes the effect was -0.30 (-0.38 to -0.21), but only -0.10 (-0.20 to 0.01) for trials with observer-reported outcomes. Of 10 clinical conditions investigated in three trials or more, placebo had a statistically significant pooled effect only on pain or phobia on continuous scales. CONCLUSION: We found no evidence of a generally large effect of placebo interventions. A possible small effect on patient-reported continuous outcomes, especially pain, could not be clearly distinguished from bias.

Humans↗

PubMed2000

Comparison of the effect of rofecoxib (a cyclooxygenase 2 inhibitor), ibuprofen, and placebo on the gastroduodenal mucosa of patients with osteoarthritis: a randomized, double-blind, placebo-controlled trial. The Rofecoxib Osteoarthritis Endoscopy Multinational Study Group.

OBJECTIVE: This randomized, double-blind study tested the hypothesis that rofecoxib, a drug that specifically inhibits cyclooxygenase 2, would cause fewer gastroduodenal ulcers than ibuprofen (in a multicenter trial), and its side effects would be equivalent to those of placebo (in a prespecified analysis combining the results with another trial of identical design). METHODS: Seven hundred seventy-five patients with osteoarthritis were randomized to receive rofecoxib at a dosage of 25 mg or 50 mg once daily, ibuprofen 800 mg 3 times daily, or placebo. Gastroduodenal ulceration was assessed by endoscopy at 6, 12, and (for active treatment) 24 weeks. The primary and secondary end points were the incidence of gastroduodenal ulcers at 12 and 24 weeks, respectively. RESULTS: Ulcers were significantly less common (P < 0.001) following treatment with rofecoxib (25 mg or 50 mg) than with ibuprofen after 12 weeks (5.3% and 8.8% versus 29.2%, respectively) or 24 weeks (9.9% and 12.4% versus 46.8%, respectively). In the combined analysis, the 12-week ulcer incidence with 25 mg rofecoxib (4.7%) and with placebo (7.3%) satisfied prespecified criteria for equivalence. CONCLUSION: At 2-4 times the therapeutically effective dose, rofecoxib caused fewer endoscopically detected ulcers than did ibuprofen. Rofecoxib at a dose of 25 mg (the highest dose recommended for osteoarthritis) satisfied prespecified criteria for equivalence to placebo.

Cyclooxygenase Inhibitors↗