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At least 19 recordsLinked to original sources
PubMed2000

Short-term low-dose corticosteroids vs placebo and nonsteroidal antiinflammatory drugs in rheumatoid arthritis.

BACKGROUND: The effect of low dose corticosteroids, equivalent to 15 mg prednisolone daily or less, in patients with rheumatoid arthritis has been questioned. We therefore performed a systematic review of trials which compared corticosteroids with placebo or non-steroidal, anti-inflammatory drugs. OBJECTIVES: To determine whether short-term (i.e. as recorded within the first month of therapy), oral low-dose corticosteroids (corresponding to a maximum of 15 mg prednisolone daily) is superior to placebo and nonsteroidal, antiinflammatory drugs in patients with rheumatoid arthritis. SEARCH STRATEGY: Medline Silverplatter, The Cochrane Controlled Trials Register, reference lists and a personal archive. SELECTION CRITERIA: All randomised studies comparing an oral corticosteroid (not exceeding an equivalent of 15 mg prednisolone daily) with placebo or a nonsteroidal, antiinflammatory drug were eligible if they reported clinical outcomes within one month after start of therapy. DATA COLLECTION AND ANALYSIS: Decisions on which trials to include were made independently by two observers based on the methods sections of the trials only. Standardised effect measures were used for the statistical analyses; the random effects model was used if P<0.10 for the test of heterogeneity. MAIN RESULTS: Ten studies, involving 320 patients, were included in the meta-analysis. Prednisolone had a marked effect over placebo on joint tenderness (standardised effect size 1.31, 95% confidence interval 0.78 to 1.83), pain (standardised effect size 1.75, 0.87 to 2.64) and grip strength (standardised effect size 0.41, 0.13 to 0.69). Measured in the original units, the differences were 12 tender joints (6 to 18) and 22 mm Hg (5 to 40) for grip strength. Prednisolone also had a greater effect than nonsteroidal, antiinflammatory drugs on joint tenderness (standardised effect size 0.63, 0.11 to 1.16) and pain (standardised effect size 1.25, 0.26 to 2.24), whereas the difference in grip strength was not significant (standardised effect size 0.31, -0.02 to 0.64). Measured in the original units, the differences were 9 tender joints (5 to 12) and 12 mm Hg (-6 to 31). The risk of adverse effects, also during moderate- and long-term use, seemed acceptable. REVIEWER'S CONCLUSIONS: Prednisolone in low doses (not exceeding 15 mg daily) may be used intermittently in patients with rheumatoid arthritis, particularly if the disease cannot be controlled by other means. Since prednisolone is highly effective, short-term placebo controlled trials studying the clinical effect of low-dose prednisolone or other oral corticosteroids are no longer necessary.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2000

Spironolactone versus placebo or in combination with steroids for hirsutism and/or acne.

BACKGROUND: Hirsutism is the presence of excessive hair growth in women and is an important cosmetic condition often resulting in severe distress. Hirsutism is most often caused by increased production of male sex hormones also known as androgens. It is also affected by increased sensitivity to androgens in the hair follicles, and the secretory glands around the hair follicles, called sebaceous glands. Spironolactone is an antiandrogen and aldosterone antagonist used to treat hirsutism. Since 1978, many studies have been conducted to determine its effectiveness. OBJECTIVES: The objective of this review was to investigate the effectiveness of spironolactone and/or in combination with steroids (oral contraceptive pill included) in reducing excess hair growth and/or acne in women. SEARCH STRATEGY: All publications of randomised controlled trials of spironolactone versus placebo and/or in combination with steroids (oral contraceptive pill included) were identified. Search strategy was developed by the Menstrual Disorder Group. All accessable electronic databases were searched. In addition, all reference lists of relevant trials were searched and drug companies contacted for details of unpublished trials. SELECTION CRITERIA: All randomised controlled comparisons of spironolactone versus: placebo steroids (oral contraceptive pill included)) spironolactone of varying dosages or spironolactone and steroids versus steroids alone when used to reduce hair growth and acne in women. DATA COLLECTION AND ANALYSIS: Four trials were included in the review, seven trials were excluded. Two other trials are awaiting assessment. All included trials were small (no more than 31 participants) randomised and controlled. Only one trial studied acne as an outcome, the remaining three were concerned with hirsutism. One trial investigated spironolactone versus placebo; one trial was a dosage studies of spironolactone; one trial compared spironolactone with spironolactone in combination with dexamethasone; the remaining trial used topical spironolactone for the treatment of acne. Major outcome measures include the following: - subjective observations - Ferriman and Gallwey hair scores - hormonal and biochemical parameters - side effects - sebum production measurement MAIN RESULTS: All sample populations were small and confidence intervals were wide. There was no significant difference between treatments for any of the observed outcomes. REVIEWER'S CONCLUSIONS: The effectiveness of treatment for either acne vulgaris or hirsutism cannot be determined due to the small sample populations involved in the trials. Its value in clinical practice is difficult to assess from currently available research.

Acne Vulgaris↗
PubMed1996

Placebo effect and placebo concept: a critical methodological and conceptual analysis of reports on the magnitude of the placebo effect.

Since 1955, when HK Beecher published his classic "The Powerful Placebo," it generally has been accepted that 35% of patients with any of a wide variety of disorders can be treated with placebos alone. In recent years, average cure rates of 70%, and up to 100%, also have been quoted. Like pharmacological preparations, placebos are credited with possessing time-effect curves; cumulation and carry-over effects; differentiated actions depending on color, size, or packaging; even toxic effects. It has been postulated that placebos can prolong life, that their effects occur in surgery as well as in medicine, and that they are mediated by endorphins. In this article source material that forms the scientific basis for such claims is examined. Analysis shows that the studies on which such ideas are based, except perhaps in bronchial asthma, do not in any way justify the conclusions drawn from them. The truth is that the placebo effect is counterfeited by a variety of factors including the natural history of the disease, regression to the mean, concomitant treatments, obliging reports, experimental subordination, severe methodological defects in the studies, misquotations, etc; even, on occasion, by the fact that the supposed placebo is actually not a placebo, but has to be acknowledged as having a specific action on the condition for which it is being given. A further reason for misjudgment is the lack of clarity of the placebo concept itself. Experimental subordination and conditioning are other areas of insufficient conceptual differentiation. The authors conclude that the literature relating to the magnitude and frequency of the placebo effect is unfounded and grossly overrated, if not entirely false. They pose the question whether the existence of the so-called placebo effect is itself not largely-or indeed totally-illusory.

Asthma↗
PubMed2001

Antibiotics versus placebo for prevention of postoperative infection after appendicectomy.

BACKGROUND: Appendicitis is the most common cause of acute abdominal pain requiring surgical intervention. The cause of appendicitis is unclear and the mechanism of pathogenesis continues to be debated. Despite improved asepsis and surgical techniques, postoperative complications, such as wound infection and intraabdominal abscess, still account for a significant morbidity. Several studies implicate that postoperative infections are reduced by administration of antimicrobial regimes. OBJECTIVES: The objective of this review is to compare the use of antibiotics with placebo or no treatment in patients undergoing appendectomy. Will these patients benefit from antimicrobial prophylaxis? The outcomes are described according to the nature of the appendix, as either simple appendicitis (including the non-infectious stage) and complicated appendicitis. This review do not attempt to compare the effect of different regimens, a clinical question that is addressed in another review undertaken by this Group (CCCG). SEARCH STRATEGY: We searched The Cochrane Controlled Trials Register (Cochrane Library 2000 issue 4), Medline (January 1966 to September 2000), Embase and the Cochrane Colorectal Cancer Group specialised register (September 2000). In addition we manually searched the reference lists of the primary identified trials. SELECTION CRITERIA: Randomised Controlled Trials (RCT) and Controlled Clinical Trials (CCT) in which any antibiotic regime were compared to placebo in patients suspected of having appendicitis undergoing appendectomy were evaluated. Both studies on children and adults were reviewed. The outcome measures of the studies were either wound infection, intraabdominal abscess, length of stay in hospital or mortality. DATA COLLECTION AND ANALYSIS: Eligibility and trial quality were assessed, recorded and cross-checked by to reviewers. MAIN RESULTS: Forty-four studies including 9298 patients were included in this review. The overall result is that use of antibiotics is superior to placebo for the outcome wound infection and intraabdominal abscess, with no apparent difference in the nature of the removed appendix. Studies exclusively on children and studies examining topical application reported results in favour to the above although the results were not significant. REVIEWER'S CONCLUSIONS: Antibiotic prophylaxis is effective in the prevention of postoperative complications in appendectomised patients, whether the administration are given pre-, per- and post-operatively and could be considered for routine in emergency appendectomies.

Abdominal Abscess↗
PubMed2000

Placebo effect in the acute treatment of migraine: subcutaneous placebos are better than oral placebos.

We carried out a meta-analysis of 22 trials to determine the comparative placebo effect of (a) subcutaneous vs. oral and (b) in-hospital vs. at-home administration in the treatment of migraine. The headache relief rates were combined from the placebo arms of these randomised clinical trials assessing the value of sumatriptan in acute treatment of migraine. The main outcome measure was the proportion of patients reclassified from severe or moderate headache severity to no or mild headache severity 2 h after the beginning of treatment. In the oral regimen 222 of 865 patients (25.7%) reported no or mild headache severity after 2 h, compared to 279 of 862 patients (32.4%) of those receiving subcutaneous placebo (6.7% difference; 95% CI 2.4-11.0%). Adjusting for treatment setting and severity of headache at baseline did not change the observed difference. After placebo treatment at home 285 of 1,054 patients (27.0%) reported no or mild headache severity after 2 h, compared to 216 of 673 patients (32.1%) among those receiving placebo in hospital (5.1 % difference; 95% CI 0.6-9.5%). When adjusted for route of administration and severity of headache at baseline, the difference in relief rates between home and hospital setting disappeared. These findings indicate that subcutaneous administration enhances the placebo effect of acute treatment of migraine. Future trials of antimigraine drugs assessing the relative efficacy of various routes of administration should use a double-dummy technique. The interpreting of placebo-controlled trial results must therefore consider that the effect in the drug arm of the trial depends in part on the route of administration.

Administration, Oral↗
PubMed2001

Antidepressants versus placebo for people with bulimia nervosa.

BACKGROUND: Bulimia Nervosa (BN) represents an important public health problem and is related to serious morbidity and even mortality. This review attempted to systematically evaluate the use of antidepressant medications compared with placebo for the treatment of bulimia nervosa. OBJECTIVES: The primary objective of this review was to determine whether using antidepressant medications was clinically effective for the treatment of bulimia nervosa. The secondary objectives were: (i) to examine whether there was a differential effect for the various classes/types of antidepressants with regard to effectiveness and tolerability (ii) to test the hypothesis that the effect of antidepressants on bulimic symptoms was independent of its effect on depressive symptoms SEARCH STRATEGY: (1) electronic searches of MEDLINE (1966 to December 2000), EMBASE (1980-December 2000), PsycLIT (to December 2000), LILACS & SCISEARCH (to 1997) (2) the Cochrane Register of Controlled Trials and the Cochrane Depression, Anxiety and Neurosis Group Register - ongoing (3) inspection of the references of all identified trials (4) contact with the pharmaceutical companies and the principal investigator of each included trial (5) inspection of the International Journal of Eating Disorders - ongoing SELECTION CRITERIA INCLUSION CRITERIA: every randomized, placebo-controlled trial in which antidepressant medications were compared to placebo to reduce the symptoms of bulimia nervosa in patients of any age or gender. Quality criteria: reports were considered adequate if they were classified as A or B according to the Cochrane Manual. The Jadad scale, with a cut off of 2 points, was applied to check the validity of the above referred criterion but was not used as an inclusion criterion. DATA COLLECTION AND ANALYSIS: Data were extracted independently by two reviewers for each included trial. Dichotomous data were evaluated by the relative risk with 95% confidence intervals (CI) around this measure, based on the random effects model; continuous data were evaluated by the standardised mean difference with the 95% CI. NNT was calculated using the inverse of the absolute risk reduction. MAIN RESULTS: Currently the review includes 16 trials comparing antidepressants with placebo: 6 trials with TCAs (imipramine, desipramine and amitryptiline), 3 with SSRIs (fluoxetine), 4 with MAOIs (phenelzine, isocarboxazid and brofaromine) and 3 with other classes of drugs (mianserine, trazodone and bupropion). Similar results were obtained in terms of efficacy for these different groups of drugs. The pooled RR for remission of binge episodes was 0.88 (95% CI 0.83-0.93; p<0,001) favoring drugs. The NNT for a mean treatment duration of 8 weeks, taking the non-remission rate in the placebo controls of 92% as a measure of the baseline risk was 9 (95% CI 6 - 16). The RR for clinical improvement, defined as a reduction of 50% or more in binge episodes was 0.63 (95% CI 0.55-0.74) and the NNT for a mean treatment duration of 9 weeks was 4 (95% CI 3 - 6), with a non-improvement rate of 67% in the placebo group. Patients treated with antidepressants were more likely to interrupt prematurely the treatment due to adverse events. Patients treated with TCAs dropped-out due to any cause more frequently that patients treated with placebo. The opposite was found for those treated with fluoxetine, suggesting it may be a more acceptable treatment. Independence between antidepressant and antibulimic effects could not be evaluated due to incomplete published data. REVIEWER'S CONCLUSIONS: The use of a single antidepressant agent was clinically effective for the treatment of bulimia nervosa when compared to placebo, with an overall greater remission rate but a higher rate of dropouts. No differential effect regarding efficacy and tolerability among the various classes of antidepressants could be demonstrated.

Antidepressive Agents↗
PubMed2002

[The concept of placebo and the effect of placebo].

The discussions about what placebo means and how its effect occurs go far back in the history of medicine. In general medicinal understanding, placebo means the subjective feeling of a positive effect in response to something that is used for curative intentions. In spite of difficulties in its definition and unknown content, its existence is generally accepted. What is discussed is its level of effectiveness in any disorder and medication. The placebo effect varies not only among diseases but also among regions and countries. Even the physicians' belief in a placebo increases its effect. Another interesting point about the placebo is its side effects. In many placebo controlled studies, the side effects of the placebo are found to be greater than those of real drugs. Different from other diseases, psychiatric disorders have strong connections with the placebo effect. The results of many studies support this idea. The increasing importance of placebos in psychiatry is really an interesting subject. For some people, the reason for this is hidden in the nature of psychiatric diseases. However, nonpharmacologic placebos such as "inspiration", "convincing", "confidence", and "belief" are believed to play a central role in psychiatry. In this article, placebo (the placebo effect) is defined, the implications of placebo in general medicine or psychiatry are discussed, and specific or nonspecific treatment methods are explained. The effects of a placebo on both the patient and the physician are emphasized. The significance of the placebo effect in psychiatry is also mentioned; and a new point of view, based upon the importance of symbolization and satisfaction is introduced in treatment and related action mechanisms.

English Abstract↗
PubMed2002

A comparison of placebo effects in clinical analgesic trials versus studies of placebo analgesia.

A previous meta-analysis of clinical analgesic trial studies showed generally low magnitudes of placebo analgesia (N. Engl. J. Med. 344 (2001) 1594). However, as studies included in their analysis used only placebo as a control condition, we conducted two meta-analyses, one in which 23 studies used only placebo as a control condition, and one in which 14 studies investigated placebo analgesic mechanisms. Magnitudes of placebo analgesic effects were much higher in the latter (mean effect size=0.95) as compared to the former (mean effect size=0.15) and were significantly different (P=0.003). This difference as well as differences in effect sizes within studies of placebo mechanisms may be parsimoniously explained by differences in expected pain levels produced by placebo suggestions and by conditioning. Furthermore, some of the studies of placebo analgesic mechanisms indicate that the magnitude of placebo analgesia is higher when the placebo analgesic effect is induced via suggestion combined with conditioning than via suggestion alone or conditioning alone. Based on these findings, we suggest that placebo analgesic effects are most optimally conceptualized in terms of perception of the placebo agent, and therefore a new definition of placebo response is proposed.

Analgesia↗
PubMed2001

Active-control trials: how would a new agent compare with placebo? A method illustrated with clopidogrel, aspirin, and placebo.

BACKGROUND: In an active-control trial with a new treatment and a comparator that has placebo-controlled trials, how might the effect of the new therapy versus placebo be estimated? For many diseases it is not ethically justified to use a placebo-control trial, yet in the United States regulatory efficacy is conceptually defined in comparison with placebo. METHODS: By use of the logarithm of the odds ratio for the active-control trial and for the placebo-controlled trials of the active-control, we estimated the effect of the new agent versus placebo. This "putative placebo" estimate assumes that the odds ratio in the active-control versus placebo trials is the same as would have been obtained had a placebo arm been possible in the trial with the new agent. A formula is given for sample size calculation in such a setting. RESULTS: Clopidogrel, an adenosine diphosphate (ADP) receptor antagonist, and aspirin were compared in the Clopidogrel Versus Aspirin in Patients at Risk of Ischemic Events (CAPRIE) Study of patients with recent myocardial infarction, recent ischemic stroke, or symptomatic peripheral arterial disease. The 40 trials comparing aspirin with placebo are summarized by the Antiplatelet Trialists' Collaboration. For the outcome cluster of stroke, myocardial infarction, or vascular mortality, the estimated odds ratio for clopidogrel versus placebo is 0.70 (95% confidence interval 0.64-0.78, P<.000001). The relative risk reduction of approximately 30% represents a clinically meaningful benefit. CONCLUSIONS: For active-control trials use of prior trials of the active-control versus placebo may be usefully used to estimate the effect of the new therapy versus a putative placebo.

Aspirin↗
PubMed2001

Is the placebo powerless? An analysis of clinical trials comparing placebo with no treatment.

BACKGROUND: Placebo treatments have been reported to help patients with many diseases, but the quality of the evidence supporting this finding has not been rigorously evaluated. METHODS: We conducted a systematic review of clinical trials in which patients were randomly assigned to either placebo or no treatment. A placebo could be pharmacologic (e.g., a tablet), physical (e.g., a manipulation), or psychological (e.g., a conversation). RESULTS: We identified 130 trials that met our inclusion criteria. After the exclusion of 16 trials without relevant data on outcomes, there were 32 with binary outcomes (involving 3795 patients, with a median of 51 patients per trial) and 82 with continuous outcomes (involving 4730 patients, with a median of 27 patients per trial). As compared with no treatment, placebo had no significant effect on binary outcomes (pooled relative risk of an unwanted outcome with placebo, 0.95; 95 percent confidence interval, 0.88 to 1.02), regardless of whether these outcomes were subjective or objective. For the trials with continuous outcomes, placebo had a beneficial effect (pooled standardized mean difference in the value for an unwanted outcome between the placebo and untreated groups, -0.28; 95 percent confidence interval, -0.38 to -0.19), but the effect decreased with increasing sample size, indicating a possible bias related to the effects of small trials. The pooled standardized mean difference was significant for the trials with subjective outcomes (-0.36; 95 percent confidence interval, -0.47 to -0.25) but not for those with objective outcomes. In 27 trials involving the treatment of pain, placebo had a beneficial effect (-0.27; 95 percent confidence interval, -0.40 to -0.15). This corresponded to a reduction in the intensity of pain of 6.5 mm on a 100-mm visual-analogue scale. CONCLUSIONS: We found little evidence in general that placebos had powerful clinical effects. Although placebos had no significant effects on objective or binary outcomes, they had possible small benefits in studies with continuous subjective outcomes and for the treatment of pain. Outside the setting of clinical trials, there is no justification for the use of placebos.

Anxiety↗
PubMed2003

Suicide risk in placebo vs active treatment in placebo-controlled trials for schizophrenia.

BACKGROUND: If there is an increased risk of suicide in the placebo arms of placebo-controlled studies in patients with schizophrenia, it would be a strong ethical argument against the conduct of placebo-controlled studies in this patient population. We tested whether the risk of suicide and attempted suicide in the placebo arms of placebo-controlled studies among patients with schizophrenia is higher than in the active treatment arms of such studies. METHODS: All placebo-controlled double-blind studies that were part of a registration dossier for the indication schizophrenia, and that were submitted to the regulatory authority of the Netherlands from January 1, 1992, through December 31, 2002, were reviewed for suicide and attempted suicide. RESULTS: In 31 studies, 7152 patients were included: 1888 in placebo groups (398.2 person-years) and 5264 in active compound groups (981.3 person-years). One suicide occurred in the placebo groups (0.05%, or an incidence rate of 251 per 100,000 years of exposure) and 1 in the active compound groups (0.02%, or an incidence rate of 102 per 100,000 years of exposure). This difference was not statistically significant. Two attempted suicides occurred in the placebo groups (0.11%, or an incidence rate of 502 per 100,000 years of exposure) and 11 in the active compound groups (0.21%, or an incidence rate of 1121 per 100,000 years of exposure). This difference was also not statistically significant. CONCLUSION: Concern about increased risk of suicide or attempted suicide in the placebo group should not be an argument against the conduct of placebo-controlled trials in schizophrenia, provided that appropriate precautions are taken.

Ambulatory Care↗
PubMed2004

Does elimination of placebo responders in a placebo run-in increase the treatment effect in randomized clinical trials? A meta-analytic evaluation.

The use of a placebo run-in phase, in which placebo responders are withdrawn from a study before random assignment to treatment condition, has been criticized as favoring the active treatment in clinical trials. We compared the effect size of randomized, placebo-controlled clinical trials (in the treatment of depression with selective serotonin reuptake inhibitors [SSRIs]) that include a placebo run-in phase with those that do not, using a meta-analytic approach. This study differed from earlier meta-analytic studies in that it considered only SSRIs and included only studies using continuous measures of depression, allowing for a more refined assessment of effect size. An extensive literature search identified 43 datasets published between 1980 and 2000 comparing placebo with SSRI and using a continuous measure of depression (usually the Hamilton Depression Rating Scale). We included only studies of at least 6 weeks' duration focusing on treatment for primary acute major depression in adults 18-65 years of age. Studies focusing on depression in specific medical illnesses were not included. Analysis of efficacy was based on 3047 subjects treated with an SSRI antidepressant and 3740 subjects treated with a placebo. There was no statistically significant difference in effect size between the clinical trials that had a placebo run-in phase followed by withdrawal of placebo responders and those trials that did not. Despite the lack of a statistically significant difference between studies of withdrawing early placebo responders and those not using this procedure, this approach is likely to continue to be used widely because it produces large absolute effect sizes. It is recommended that future studies clearly describe these procedures and report the number of subjects dropped from the study for early placebo response and other reasons.

Antidepressive Agents, Second-Generation↗
PubMed2000

A critique of recent studies on placebo effects of antidepressants: importance of research on active placebos.

OBJECTIVE: This review examines the recent literature on placebo effects in antidepressant drug research. Recent meta-analyses have suggested that antidepressants produce relatively small effects compared to placebo treatments, and that the effect sizes for placebo treatments are highly correlated with effect sizes for drug treatments across different studies. In addition, it is argued that "active placebos", i.e., drugs that are not antidepressants but do have discernible subjective or physiological effects, can also produce substantial changes on measures of depression. Thus, some researchers have called into question the "blind" nature of research using inert placebos, and also have questioned the efficacy of antidepressant drugs. RESULTS: The studies reviewed indicate that it is premature to suggest that antidepressant drugs have little efficacy beyond their role as active placebos. In fact, there are several important methodological, conceptual and scholarly problems with some of the work that emphasizes the role of placebo effects in mediating the actions of antidepressant drugs. CONCLUSIONS: Many of the drugs listed as "active placebos" actually have some efficacy for the treatment of depression or related disorders, and several of these drugs are used clinically to augment the effects of antidepressants. It would be important for researchers to identify new active placebos as research tools in this area, and to focus on discriminating between placebo effects and the true therapeutic actions of antidepressant drugs. A new generation of well controlled experiments in this area could shed light on these important issues, and may lead to improved methods for the determination of antidepressant efficacy.

Antidepressive Agents↗
PubMed1998

The specific effects of prior opioid exposure on placebo analgesia and placebo respiratory depression.

Although in most of the cases the placebo response appears to be unpredictable, several factors have been considered in order to explain the placebo analgesic effect. For example, it is widely recognized, albeit with little empirical evidence, that placebo analgesia is more likely to occur after a successful analgesic therapy. On the basis of this assumption, we tested the placebo response in a population of patients who were treated with buprenorphine the day before for relieving postoperative pain. However, due to the high variability of opioid responsiveness, buprenorphine was effective in some patients and poorly effective in some others. Similarly, buprenorphine produced respiratory depression with a large variability, ranging from mild depression to no effect. We found that the placebo analgesic response depended on the buprenorphine analgesic effectiveness of the previous day. Analogously, we found that a placebo respiratory depressant response was more pronounced in those patients with a respiratory depressant response to buprenorphine on the day before, irrespective of the analgesic effectiveness. These specific effects suggest that (1) the placebo effect is experience-dependent; (2) the mechanisms underlying placebo analgesia and placebo respiratory depression are independent from each other and, by considering the role of endogenous opioids in placebo analgesia, might involve different subpopulations of opioid receptors.

Analgesia↗
PubMed1994

Does a placebo run-in or a placebo treatment cell affect the efficacy of antidepressant medications?

During the last decade, there has been an increasing use of a placebo run-in period prior to randomization to active treatments, or placebo in randomized controlled trials aimed at establishing acute phase antidepressant drug efficacy in patients with major depression. This procedure is thought to reduce response rates to placebo treatment after randomization, thereby increasing the drug-placebo difference. Metaanalyses of 101 studies reveal that a placebo run-in does not (1) lower the placebo response rate, (2) increase the drug-placebo difference, or (3) affect the drug response rate post-randomization in either inpatients or outpatients for any antidepressant drug group. If there is a post-randomization placebo treatment cell, drug response rates are unchanged or are slightly lower than if there is no placebo treatment cell for outpatients. These results suggest that a pill placebo run-in provides no advantage in acute phase efficacy trials.

Antidepressive Agents↗