When placebo controlled trials are essential and equivalence trials are inadequate

Perspective Chapter: Ethics of Using Placebo Controlled Trials for Covid-19 Vaccine Development in Vulnerable Populations

When clinical trials are conducted in vulnerable communities such as those found within low-to-middle-income-countries (LMICs), there is always the risk of exploitation or harm to these communities during the course of biomedical research. Historically, there have been multiple instances where significant harm was caused. Various organisations have proposed guidelines to minimise the risk of this occurring, however, questionable clinical trials are still conducted. Research Ethics Committees have an additional duty of care to protect these vulnerable populations. During the Covid-19 pandemic the ongoing use of placebo-controlled trials (PCTs), even after approval of a safe and efficacious vaccine, is a topic of great debate and is discussed from an ethical and moral perspective.

Spinal Manipulative Therapy for Acute Neck Pain: A Systematic Review and Meta-Analysis of Randomised Controlled Trials

(1) Background: Acute neck pain is common and usually managed by medication and/or manual therapy. General practitioners (GPs) hesitate to refer to manual therapy due to uncertainty about the effectiveness and adverse events (AEs); (2) Method: To review original randomized controlled trials (RCTs) assessing the effect of spinal manipulative therapy (SMT) for acute neck pain. Data extraction was done in duplicate and formulated in tables. Quality and evidence were assessed using the Cochrane Back and Neck (CBN) Risk of Bias tool and the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) criteria, respectively; (3) Results: Six studies were included. The overall pooled effect size for neck pain was very large −1.37 (95% CI, −2.41, −0.34), favouring treatments with SMT compared with controls. A single study that showed that SMT was statistically significantly better than medicine (30 mg ketorolac im.) one day post-treatment, ((−2.8 (46%) (95% CI, −2.1, −3.4) vs. −1.7 (30%) (95% CI, −1.1, −2.3), respectively; p = 0.02)). Minor transient AEs reported included increased pain and headache, while no serious AEs were reported; (4) Conclusions: SMT alone or in combination with other modalities was effective for patients with acute neck pain. However, limited quantity and quality, pragmatic design, and high heterogeneity limit our findings.

Attitudes of patients and surgeons towards sham surgery trials: a protocol for a scoping review of attributes to inform a discrete choice experiment

INTRODUCTION

In order to properly evaluate the efficacy of orthopaedic procedures, rigorous, randomised controlled sham surgery trial designs are necessary. However, randomised controlled trials (RCTs) for surgery involving a placebo are ethically debated and difficult to conduct with many failing to reach their desired sample size and power. A review of the literature on barriers and enablers to recruitment, and patient and surgeon attitudes and preferences towards sham surgery trials, will help to determine the characteristics necessary for successful recruitment.

METHODS AND ANALYSIS

This review will scope the diverse literature surrounding sham surgery trials with the aim of informing a discrete choice experiment to empirically test patient and surgeon preferences for different sham surgery trial designs. The scoping review will be conducted in accordance with the methodological framework described in Arksey and O'Malley (2005) and reported using the Preferred Reporting Items for Systematic Reviews and Meta-analyses Protocols extension for Scoping Reviews. The review will be informed by a systematic search of Medline, Embase, PsycInfo, CINAHL and EconLit databases (from database inception to 21 June 2019), a Google Scholar search, and hand searching of reference lists of relevant studies or reviews. Studies or opinion pieces that involve patient, surgeon or trial characteristics, which influence the decision to participate in a trial, will be included. Study selection will be carried out independently by two authors with discrepancies resolved by consensus among three authors. Data will be charted using a standardised form, and results tabulated and narratively summarised with reference to the research questions of the review.

ETHICS AND DISSEMINATION

The findings from this review will inform the design of a discrete choice experiment around willingness to participate in surgical trials, the outcomes of which can inform decision and cost-effectiveness models of sham surgery RCTs. The qualitative information from this review will also inform patient-centred outcomes research. The review will be published in a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

CRD42019133296.

Parental Attitudes About Placebo Use in Children

OBJECTIVE

To assess parental attitudes regarding placebo use in pediatric randomized controlled trials and clinical care.

STUDY DESIGN

Parents with children under age 18 years living in the US completed and submitted an online survey between September and November 2014.

RESULTS

Among all 1300 participants, 1000 (76.9%; 538 mothers and 462 fathers) met the study inclusion criteria. The majority of surveyed parents considered the use of placebos acceptable in some pediatric care situations (86%) and some pediatric trials (91.5%), whereas only 5.7% of parents found the use of placebos in children always unacceptable. The clinical use of placebo was considered acceptable by a majority of parents for only 7 (mostly psychological) of the 17 conditions presented. Respondents' judgment about acceptability was influenced by the doctors' opinions about the therapeutic benefits of placebo treatment, the conditions for pediatric placebo use, transparency, safety, and purity of placebos.

CONCLUSION

Most surveyed parents accepted the idea of using placebos in pediatric trials and within the clinic for some conditions without the practice of deception and with the creation of guidelines for ethical and safe use. This study suggests a need to reconsider pediatric trial design and clinical therapy in the light of generally positive parental support of appropriate placebo use.

Effect of Thalidomide on Clinical Remission in Children and Adolescents with Ulcerative Colitis Refractory to Other Immunosuppressives: Pilot Randomized Clinical Trial

BACKGROUND

In a randomized controlled trial, thalidomide has shown to be effective in refractory Crohn's disease in children. This pilot study aimed at evaluating thalidomide in refractory pediatric ulcerative colitis (UC).

METHODS

Double-blind, placebo-controlled randomized clinical trial on thalidomide 1.5 to 2.5 mg/kg/day in children with active UC despite multiple immunosuppressive treatments. In an open-label extension, nonresponders to placebo received thalidomide for an additional 8 weeks; all responders were followed up for a minimum of 52 weeks.

RESULTS

Twenty-six children with refractory UC were randomized to thalidomide or placebo. Clinical remission at week 8 was achieved by significantly more children treated with thalidomide {10/12 (83.3%) versus 2/11 (18.8%); risk ratio, 4.5 (95% confidence interval [CI], 1.2-16.4); P = 0.005; number needed to treat, 1.5}. Of the nonresponders to placebo who were switched to thalidomide, 8 of 11 (72.7%) subsequently reached remission at week 8 (risk ratio, 4.0 [95% CI, 1.1-14.7]; number needed to treat, 2.45; P = 0.01). Clinical remission in the thalidomide group was 135.0 weeks (95% CI, 32-238), compared with 8.0 weeks (95% CI, 2.4-13.6) in the placebo group (P < 0.0001). Cumulative incidence of severe adverse events was 3.1 per 1000 patient-weeks. Peripheral neuropathy and amenorrhea were the most frequent adverse events.

CONCLUSIONS

In this pilot randomized controlled trial on cases of UC refractory to immunosuppressive therapy, thalidomide compared with placebo resulted in improved clinical remission at 8 weeks of treatment and in longer term maintenance of remission. These findings require replication in larger clinical studies evaluating both thalidomide efficacy and safety.

Immediate rescue designs in pediatric analgesic trials: a systematic review and meta-analysis

BACKGROUND

Designing analgesic clinical trials in pediatrics requires a balance between scientific, ethical, and practical concerns. A previous consensus group recommended immediate rescue designs using opioid sparing as a surrogate measure of analgesic efficacy. The authors summarize the performance of rescue analgesic designs in pediatric trials of four commonly used classes of analgesics: opioids, nonsteroidal antiinflammatory drugs, acetaminophen, and local anesthetics.

METHODS

MEDLINE, Embase, CINAHL, The Cochrane Library, and Web of science were searched in April 2013. The 85 studies selected were randomized or controlled clinical trials using immediate rescue paradigms in postoperative pain settings. A random-effects meta-analysis was used to synthesize predefined outcomes using Hedges' g. Difference between the means of the treatment arms were also expressed as a percentage of the corresponding value in the placebo group (placebo-treatment/placebo). Distributions of pain scores in study and control groups and relationships between opioid sparing and pain scores were examined.

RESULTS

For each of the four study drug classes, significant opioid sparing was demonstrated in a majority of studies by one or more of the following endpoints: (1) total dose (milligram per kilogram per hour), (2) percentage of children requiring rescue medication, and (3) time to first rescue medication (minutes). Pain scores averaged 2.4/10 in study groups, 3.4/10 in control groups.

CONCLUSIONS

Opioid sparing is a feasible pragmatic endpoint for pediatric pain analgesic trials. This review serves to guide future research in pediatric analgesia trials, which could test whether some specific design features may improve assay sensitivity while minimizing the risk of unrelieved pain.

Use of placebos in Phase 1 preventive HIV vaccine clinical trials

Phase 1 preventive HIV vaccine trials are often designed as randomized, double-blind studies with the inclusion of placebo recipients. Careful consideration is needed to determine when the inclusion of placebo recipients is highly advantageous and when it is optional for achieving the study objectives of assessing vaccine safety, tolerability and immunogenicity. The inclusion of placebo recipients is generally important to form a reference group that ensures fair evaluation and interpretation of subjective study endpoints, or endpoints whose levels may change due to exposures besides vaccination. In some settings, however, placebo recipients are less important because other data sources and tools are available to achieve the study objectives.

Incentive spirometry for preventing pulmonary complications after coronary artery bypass graft

BACKGROUND

Incentive spirometry (IS) is a treatment technique that uses a mechanical device to reduce pulmonary complications during postoperative care. This is an update of a Cochrane review first published in 2007.

OBJECTIVES

Update the previously published systematic review to compare the effects of IS for preventing postoperative pulmonary complications in adults undergoing coronary artery bypass graft (CABG).

SEARCH METHODS

We searched CENTRAL and DARE on The Cochrane Library (Issue 2 of 4 2011), MEDLINE OVID (1948 to May 2011), EMBASE (1980 to Week 20 2011), LILACS (1982 to July 2011) , the Physiotherapy Evidence Database (PEDro) (1980 to July 2011), Allied & Complementary Medicine (AMED) (1985 to May 2011), CINAHL (1982 to May 2011).

SELECTION CRITERIA

Randomised controlled trials comparing IS with any type of prophylactic physiotherapy for prevention of postoperative pulmonary complications in adults undergoing CABG.

DATA COLLECTION AND ANALYSIS

Two reviewers independently evaluated trial quality using the guidelines of the Cochrane Handbook for Systematic Reviews and extracted data from included trials. For continuous outcomes, we used the generic inverse variance method for meta-analysis and for dichotomous data we used the Peto Odds Ratio.

MAIN RESULTS

This update included 592 participants from seven studies (two new and one that had been excluded in the previous review in 2007. There was no evidence of a difference between groups in the incidence of any pulmonary complications and functional capacity between treatment with IS and treatment with physical therapy, positive pressure breathing techniques (including continuous positive airway pressure (CPAP), bilevel positive airway pressure (BiPAP) and intermittent positive pressure breathing (IPPB), active cycle of breathing techniques (ACBT) or preoperative patient education. Patients treated with IS had worse pulmonary function and arterial oxygenation compared with positive pressure breathing. Based on these studies there was no improvement in the muscle strength between groups who received IS demonstrated by maximal inspiratory pressure and maximal expiratory pressure .

AUTHORS' CONCLUSIONS

Our update review suggests there is no evidence of benefit from IS in reducing pulmonary complications and in decreasing the negative effects on pulmonary function in patients undergoing CABG. In view of the modest number of patients studied, methodological shortcomings and poor reporting of the included trials, these results should still be interpreted cautiously. An appropriately powered trial of high methodological rigour is needed to determine if there are patients who may derive benefit from IS following CABG.

Pediatric analgesic clinical trial designs, measures, and extrapolation: report of an FDA scientific workshop

Analgesic trials pose unique scientific, ethical, and practical challenges in pediatrics. Participants in a scientific workshop sponsored by the US Food and Drug Administration developed consensus on aspects of pediatric analgesic clinical trial design. The standard parallel-placebo analgesic trial design commonly used for adults has ethical and practical difficulties in pediatrics, due to the likelihood of subjects experiencing pain for extended periods of time. Immediate-rescue designs using opioid-sparing, rather than pain scores, as a primary outcome measure have been successfully used in pediatric analgesic efficacy trials. These designs maintain some of the scientific benefits of blinding, with some ethical and practical advantages over traditional designs. Preferred outcome measures were recommended for each age group. Acute pain trials are feasible for children undergoing surgery. Pharmacodynamic responses to opioids, local anesthetics, acetaminophen, and nonsteroidal antiinflammatory drugs appear substantially mature by age 2 years. There is currently no clear evidence for analgesic efficacy of acetaminophen or nonsteroidal antiinflammatory drugs in neonates or infants younger than 3 months of age. Small sample designs, including cross-over trials and N of 1 trials, for particular pediatric chronic pain conditions and for studies of pain and irritability in pediatric palliative care should be considered. Pediatric analgesic trials can be improved by using innovative study designs and outcome measures specific for children. Multicenter consortia will help to facilitate adequately powered pediatric analgesic trials.

The placebo mystique: Implications for clinical trial methodology

AIM

The World Medical Association Declaration of Helsinki states that the use of a placebo in a clinical trial can only be justified ethically when no proven active treatment is available as a comparison. Despite this, placebos remain a popular choice as controls in clinical trials. Recent literature reviews have suggested that reliance on placebos may, in part, be because of methodological misconceptions about the need for placebos to control for the 'placebo effect'. This study aimed to assess doctors' understanding of the requirements for placebo use in clinical trials.

METHODS

Two hundred doctors working in tertiary hospitals in Melbourne, Australia were surveyed in regards to their understanding of the role of the placebo and placebo effects in clinical trials. There was a 72% response rate. Doctors were specifically asked if a placebo was required in a randomised clinical trial, in preference to another form of control, to control for the 'placebo effect'.

RESULTS

The majority of respondents (62%) incorrectly believed that placebos are essential to control for the 'placebo effect' in a randomised clinical trial.

CONCLUSIONS

Misconceptions about the methodological requirement for placebos in randomised controlled trials may influence researcher decisions to use placebo controls in unethical situations.

Non-inferiority trials: determining whether alternative treatments are good enough

New treatments that are potentially as effective as existing treatments are increasingly being developed, some of which may be preferred because of lower cost, fewer side effects, easier administration or less harm. Non-inferiority trials attempt to establish whether or not a new treatment -- drug or non-drug -- is no worse than an established treatment for which efficacy has been determined in placebo-controlled trials. Critical issues in the design and conduct of non-inferiority trials include: defining the acceptable margin of adverse events that, if exceeded, will render the new treatment inferior to the standard treatment (the non-inferiority margin); calculating the sample size needed to demonstrate non-inferiority; assessing the robustness of results in terms of absolute versus relative effects, intention-to-treat versus per-protocol analyses, one-sided versus two-sided statistical tests, and observed versus expected event rates for standard treatment; evaluating all relevant outcomes, including harm; and stating conclusions that are consistent with aims and results. Many non-inferiority trials fail to meet basic quality criteria, report biased and misleading conclusions, and are unduly influenced by commercial sponsors, with some commentators going so far as labelling them unethical. Clinicians and trial investigators need to exercise caution when interpreting results of non-inferiority trials which, because they lack a placebo group, can only provide an indirect assessment of the efficacy of a new treatment compared with an existing standard, and where the choice of non-inferiority margin can be highly subjective.

[Clinical significance of the placebo effect]

Placebo controlled studies examining clinical problems, e.g. in pain therapy, are considered the "gold standard" for evidence-based medicine. In these studies the placebo effect itself is not the main focus of interest, but serves more as a control for the specificity of the effect of a certain treatment. What physicians in this context often do not realize is that the placebo effect itself represents a true measurable correlate of an organism's psycho-neurobiological response and, thereby, influences the healing process, e.g. the pain relief. Placebo is, therefore, not equivalent to "no treatment". The number of placebo responders, the degree and the duration of the placebo effect is not fixed, but are subject to a much greater variability then hitherto believed. The myth that placebo responders have a certain personality has not been proven correct; instead, the relationships between physicians and patients as well as sociocultural factors have a considerable impact on the placebo effect. Psychological theories explain that classical conditioning, enhanced expectation and motivation of the patient determine the degree of the placebo effect. These directly influence neurobiological systems such as the endogenous opioids which according to modern brain imaging are predominantly activated in pain-relevant areas and contribute to the effect of placebo analgesia. Placebo effects that should be deliberately excluded in controlled clinical trials, can be desirable in clinical practice to optimize the total therapeutic effect. This should mean that the context effect of each therapeutic intervention is maximized towards an improved therapeutic effect, as outlined in the recent AWMF guidelines for postoperative pain therapy, but should not include the administration of an inert substance. The latter is controlled by rigorous ethical guidelines and is only permitted in the context of ethically approved controlled clinical trials. A possible alternative is suggested by Benedetti et al. in which the hidden administration of an active substance identifies the specific response in contrast to the open application of the same substance characterizing the specific plus the placebo effect, after which the pure placebo effect can be determined.

Incentive spirometry for preventing pulmonary complications after coronary artery bypass graft

BACKGROUND

Following coronary artery bypass graft (CABG), the main causes of postoperative morbidity and mortality are postoperative pulmonary complications, respiratory dysfunction and arterial hypoxemia. Incentive spirometry is a treatment technique that uses a mechanical device (an incentive spirometer) to reduce such pulmonary complications during postoperative care.

OBJECTIVES

To assess the effects of incentive spirometry for preventing postoperative pulmonary complications in adults undergoing CABG.

SEARCH STRATEGY

We searched CENTRAL on The Cochrane Library (Issue 2, 2004), MEDLINE (1966 to December 2004), EMBASE (1980 to December 2004), LILACS (1982 to December 2004), the Physiotherapy Evidence Database (PEDro) (1980 to December 2004), Allied & Complementary Medicine (AMED) (1985 to December 2004), CINAHL (1982 to December 2004), and the Database of Abstracts of Reviews of Effects (DARE) (1994 to December 2004). References were checked and authors contacted. No language restrictions were applied.

SELECTION CRITERIA

Randomized controlled trials comparing incentive spirometry with any type of prophylactic physiotherapy for prevention of postoperative pulmonary complications in adults undergoing CABG.

DATA COLLECTION AND ANALYSIS

Two reviewers independently evaluated the quality of trials using the guidelines of the Cochrane Reviewers' Handbook and extracted data from included trials.

MAIN RESULTS

Four trials with 443 participants contributed to this review. There was no significant difference in pulmonary complications (atelectasis and pneumonia) between treatment with incentive spirometry and treatment with positive pressure breathing techniques (continuous positive airway pressure (CPAP), bilevel positive airway pressure (BiPAP) and intermittent positive pressure breathing (IPPB)) or preoperative patient education. Patients treated with incentive spirometry had worse pulmonary function and arterial oxygenation compared with positive pressure breathing (CPAP, BiPAP, IPPB).

AUTHORS' CONCLUSIONS

Individual small trials suggest that there is no evidence of benefit from incentive spirometry in reducing pulmonary complications and in decreasing the negative effects on pulmonary function in patients undergoing CABG. In view of the modest number of patients studied, methodological shortcomings and poor reporting of the included trials, these results should be interpreted cautiously. An appropriately powered trial of high methodological rigour is needed to determine those patients who may derive benefit from incentive spirometry following CABG.

Oral β-lactams applied to uncomplicated infections of skin and skin structures

Uncomplicated skin and skin structure infections (uSSSIs) include impetigo, erysipelas, folliculitis, simple abscesses, and cellulitis. Their common bacterial causative agents include Staphylococcus aureus and Streptococcus pyogenes. Current guidelines predate the widespread occurrences of methicillin-resistant S. aureus (MRSA) as a community-acquired pathogen and include dicloxacillin, cephalexin, erythromycin, clindamycin, and amoxicillin/clavulanic acid, all orally, or mupirocin ointment applied topically, for impetigo. For other uSSSI, recommendations are based on the probability of the infection being caused by MRSA. If methicillin-susceptible S. aureus (MSSA) are known or suspected, the oral agents recommended include clindamycin, dicloxacillin, cephalexin, doxycycline, minocycline, and trimethoprim-sulfamethoxazole (SXT). For MRSA, recommended oral agents are linezolid, clindamycin, doxycycline, minocycline, and SXT. Because community-acquired MRSA infections now predominate in patients with abscesses in the United States, agents recommended for MRSA should be used for this indication. Local susceptibility patterns should guide empiric therapy. However, no placebo-controlled trials of uSSSI are available, and the evidence used to generate these recommendations is based on comparative noninferiority studies, often with wide noninferiority margins and confidence intervals. The evidence used in developing current guidelines therefore has significant limitations. Further studies, such as superiority outcome studies, placebo-controlled studies, measurement of time to resolution, or other novel approaches, are needed to resolve these treatment dilemmas. Until such studies are performed, the best surrogate available for predicting clinical outcome is application of pharmacokinetic and pharmacodynamic principles; these describe in vivo drug behavior and allow determination of susceptibility breakpoints for predicting in vivo antimicrobial efficacy via attainment of antimicrobial targets.

Respiratory physiotherapy to prevent pulmonary complications after abdominal surgery: a systematic review

OBJECTIVES

To examine the efficacy of respiratory physiotherapy for prevention of pulmonary complications after abdominal surgery.

METHODS

We searched in databases and bibliographies for articles in all languages through November 2005. Randomized trials were included if they investigated prophylactic respiratory physiotherapy and pulmonary outcomes, and if the follow-up was at least 2 days. Efficacy data were expressed as risk differences (RDs) and number needed to treat (NNT), with 95% confidence intervals (CIs).

RESULTS

Thirty-five trials tested respiratory physiotherapy treatments. Of 13 trials with a "no intervention" control group, 9 studies (n = 883) did not report on significant differences, and 4 studies (n = 528) did: in 1 study, the incidence of pneumonia was decreased from 37.3 to 13.7% with deep breathing, directed cough, and postural drainage (RD, 23.6%; 95% CI, 7 to 40%; NNT, 4.3; 95% CI, 2.5 to 14); in 1 study, the incidence of atelectasis was decreased from 39 to 15% with deep breathing and directed cough (RD, 24%; 95% CI, 5 to 43%; NNT, 4.2; 95% CI, 2.4 to 18); in 1 study, the incidence of atelectasis was decreased from 77 to 59% with deep breathing, directed cough, and postural drainage (RD, 18%; 95% CI, 5 to 31%; NNT, 5.6; 95% CI, 3.3 to 19); in 1 study, the incidence of unspecified pulmonary complications was decreased from 47.7% to 21.4 to 22.2% with intermittent positive pressure breathing, or incentive spirometry, or deep breathing with directed cough (RD, 25.5 to 26.3%; NNT, 3.8 to 3.9). Twenty-two trials (n = 2,734) compared physiotherapy treatments without no intervention control subjects; no conclusions could be drawn.

CONCLUSIONS

There are only a few trials that support the usefulness of prophylactic respiratory physiotherapy. The routine use of respiratory physiotherapy after abdominal surgery does not seem to be justified.

Systematic review on the recurrence of postoperative nausea and vomiting after a first episode in the recovery room - implications for the treatment of PONV and related clinical trials

Background

Despite the presence of a plethora of publications on the prevention of postoperative nausea and vomiting (PONV) only little is known how to treat established symptoms. Besides the high effort of performing these efficacy trials (much more patients must give their consent than are actually included in a study) and ethical concerns, little is known about the rate of re-occurring PONV/vomiting after placebo. As a consequence investigators will have difficulties defining a clinically relevant effect for the new treatment which is crucial for any planning. A quantitative systematic review was performed in order to provide more reliable estimates of the incidence of re-occurring PONV/vomiting after placebo and to help investigators defining a clinically relevant treatment effect.

Methods

A systematic search of the literature was performed using an extended search strategy of a previous review. Data on the recurrence of PONV (any nausea or emetic symptom) and vomiting (retching or vomiting) was extracted from published reports treating PONV with placebo and unpublished results from two observational trials where no treatment was given. A nonlinear random effects model was used to calculate estimates of the recurrence of symptoms and their 95%-confidence intervals (95%-CI).

Results

A total of 29 trials (including the unpublished data) were eligible for the calculations. Depending on the length of observation after administering placebo or no treatment the recurrence rate of PONV was between 65% (95%-CI: 53%...75%) and 84% (95%-CI: 73%...91%) and that of vomiting was between 65% (95%-CI: 44%...81%) and 78% (95%-CI: 59%...90%).

Conclusion

Almost all trials showed a considerable and consistently high rate of recurrence of emetic symptoms after placebo highlighting the need for a consequent antiemetic treatment. Future (placebo) controlled efficacy trials may use the presented empirical estimates for defining clinically relevant effects and for statistical power considerations.

The challenges of new drugs benefits and risks analysis: Lessons from the ximelagatran FDA Cardiovascular Advisory Committee

Ximelagatran is a new oral anticoagulant that acts by direct and reversible inhibition of thrombin and has the potential to replace warfarin. In 2004, the FDA Cardiovascular and Renal drug Advisory Committee (CRAC) reviewed the ximelagatran clinical program. Three indications were proposed: the prevention of venous thromboembolism (VTE) in patients undergoing total knee replacement surgery (TKR), the prevention of stroke and other thromboembolic complications associated with atrial fibrillation (AF), and the long-term secondary prevention of VTE after standard treatment of an episode of acute VTE. The database consisted of a total of 30,698 subjects and included five phase III pivotal studies. During the advisory panel debate, widely divergent analyses of the benefits and risks of ximelagatran were presented. Ximelagatran hepatic toxicity was a key feature leading the CRAC to conclude that the benefit risk ratio of ximelagtran was unfavorable for the three proposed indications. Some design issues also undermined the strength of efficacy data. This paper reviews the benefits and risks of ximelagatran and analyzes the reasons leading to conflicting conclusions among various experts. The aim of this review is to facilitate the interpretation of benefits and risks associated with a new drug product and to improve future clinical drug developments.

Are placebo-controlled trials still important for obsessive compulsive disorder?

The use of placebos as reference agents in randomised controlled trials for psychiatric disorders has come under question for ethical reasons. Alternative methods for validating the efficacy of new treatments exist, but may not be as reliable as placebo. In this paper we examine arguments for and against the ongoing use of placebo agents in the development of new treatments for obsessive compulsive disorder in the context of evidence from randomised controlled trials.

Selecting an appropriate placebo for a trial of spinal manipulative therapy

Selecting an appropriate control group or placebo for randomised controlled trials of spinal manipulative therapy is essential to the final interpretation and usefulness of these studies. Prior to starting a randomised controlled trial of spinal manipulative therapy for acute low back pain we wanted to ensure that the placebo selected would be considered appropriate by experts in the field thereby making the results more likely to be accepted and more likely to influence clinical practice. We developed ten placebo techniques that aimed to mimic spinal manipulative therapy as closely as possible which, while not including the active component of spinal manipulative therapy, were still credible. This list of placebo techniques with detailed descriptions was sent to 25 experts in the field from Australia and New Zealand including both clinicians and academics. We asked the experts to rate whether they believed each technique was appropriate for use as a placebo in a trial of spinal manipulative therapy. Sixteen (64%) of the experts responded. There were extremely low levels of agreement between the experts on which placebos were appropriate (kappa = 0.05, 95% CI 0.01 to 0.10). For nine of the ten placebos at least one expert considered the placebo to include the active component of spinal manipulative therapy while at least one other expert believed the same placebo was not only not active but also not credible. The results of this study demonstrate the different views of experts on what constitutes an appropriate placebo for trials of spinal manipulative therapy. Different beliefs about what is the active component of spinal manipulative therapy appear to be responsible for much of the disagreement.

Economic evaluation of ondansetron vs dimenhydrinate for prevention of postoperative vomiting in children undergoing strabismus surgery

BACKGROUND

Although rarely life-threatening, postoperative vomiting (POV) is a distressing complication. The incidence of POV ranges from 34 to 90% in children undergoing strabismus surgery when antiemetics are not administered prophylactically.

METHODS

In this study, a cost-consequence analysis (CCA) is used to estimate the economic benefit of ondansetron and dimenhydrinate as antiemetics administered prophylactically in children undergoing strabismus surgery. This retrospective study was conducted at The Hospital for Sick Children based on a review of 70 charts.

RESULTS

Ondansetron was more effective with 45.3 POV-free patients (PFP) in an adjusted cohort of 100, while dimenhydrinate resulted in 38.2 PFP in an adjusted cohort of 100. The costs were significantly different between the two groups, CAD dollars 185.90 (+/-26.37, 95% CI, CAD dollars 173,89; CAD dollars 197.90) and CAD dollars 232.90 (+/-CAD dollars 66.84, 95% CI, CAD dollars 198.53; CAD dollars 267.27) per patient for ondansetron and dimenhydrinate, respectively. The length of stay in the postanesthetic care unit (PACU) represented over 97% of total costs, and the mean lengths of stay in the PACU for ondansetron and dimenhydrinate were significantly different, 3.43 and 4.41 h, respectively.

CONCLUSION

This study should serve as a pilot for a large-scale investigation on the correlation between the length of stay in the PACU and the antiemetic agent used.

Double-blind randomised trial comparing 5-fluorouracil plus leucovorin to placebo for metastatic colorectal carcinoma

OBJECTIVE

Previous randomised trials of chemotherapy for metastatic colorectal cancer have not concealed the allocation of treatment from participants. Most of these unblinded trials showed improved survival with chemotherapy. This trial used a double-blind design to test the hypothesis that there is no difference between the effect of 5-fluorouracil plus leucovorin and the effect of placebo on the survival of subjects with metastatic colorectal cancer.

PATIENTS AND METHODS

In one hospital, 147 subjects with metastatic colorectal cancer were studied from 1989 to 2001. 73 were allocated chemotherapy with 5-fluorouracil plus leucovorin. 74 were allocated placebo. The primary end point was survival after randomization. Secondary end points were performance score, quality of life, serum level of carcinoembryonic antigen (CEA) and toxicity of treatment.

RESULTS

One hundred and forty-two patients were followed up until death. The median survival time in the chemotherapy group was 8.7 months (95% confidence interval (CI) 6.9-11.0 months) compared to 6.7 months in the placebo group (95% CI 5.3-7.9 months). Chemotherapy did not affect performance status but slowed the rise of CEA and caused appreciable toxicity.

CONCLUSIONS

In this double-blind trial, chemotherapy with 5-fluorouracil plus leucovorin did not improve survival, did not impair performance, but caused appreciable toxicity.

Clinical trials in urology: how many patients are required to achieve statistically significant results?

During the clinical validation of a new drug there are several clinical phases. Once phase II studies have defined the efficacy of a new drug, clinical research is used to evaluate its significance in clinical practice, comparing it with other drugs or treatments in use for similar clinical conditions. The group of patients undergoing standard treatment (either untreated or treated with placebo) is thus used as a control; these phase III studies are termed 'controlled clinical studies'. The general condition for comparing patients treated with the new drug is that they do not have characteristics (relevant to the study) that are systematically different from those in the control group. Randomization guarantees comparability between treated and untreated (or otherwise treated) patients. The comparability of the observations of the studied events are guaranteed by blinding and placebo. The fundamental question when designing a controlled clinical study to evaluate whether there are differences between two or more treatments is how many patients are needed. Generally, the smaller the clinically relevant differences in efficacy between treatments, the more patients are required, to provide sufficient statistical power and meaningful clinical results. A group of randomized patients represents the final point of sequential steps. Also of importance is to what kind of 'population' the results from the studied sample can be applied (qualitatively, not necessarily quantitatively), i.e. the general applicability of a study, or whether the findings can be used to treat future patients with the same or similar characteristics as those randomized, or to all patients with the same pathology. Answers to these questions depend on many aspects of the randomized selection mechanisms, the disease characteristics, and knowledge of the biological effects of the drug to be tested.

Is it always unethical to use a placebo in a clinical trial?

Placebos are used in trials to conceal whether a treatment is being given or not and hence to control for the psychosomatic effects of offering treatment. Placebo-controlled trials are controversial. Critics of such trials argue that if a proven effective therapy exists, a placebo should not be used. But proponents argue that placebo trials are still crucial to prove the efficacy and safety of many treatments.

Strategies for postoperative nausea and vomiting

Significant improvement towards a better control of postoperative nausea and vomiting have been achieved in recent years. Today, we understand better who is likely to vomit or to be nauseous after surgery. Significant amounts of the huge literature on anti-emetic interventions have been systematically reviewed, critically appraised and quantitatively synthesized. Thus, we know what anti-emetic interventions work, and how well they work, and we know their adverse effect profile. We also know which interventions have no worthwhile efficacy. A rational approach to postoperative nausea and vomiting includes three steps: identification of patients at risk, keeping the baseline risk low, and prophylactic administration of anti-emetics in those patients who are most likely to need them. For patients who are identified as high-risk patients, all measurements should be simultaneously initiated (multimodal anti-emesis).

A Randomized Controlled Comparison of Electro-Acupoint Stimulation or Ondansetron Versus Placebo for the Prevention of Postoperative Nausea and Vomiting

In this study we evaluated the efficacy of electro-acupoint stimulation, ondansetron versus placebo for the prevention of postoperative nausea and vomiting (PONV). Patients undergoing major breast surgery under general anesthesia were randomized into active electro-acupoint stimulation (A), ondansetron 4 mg IV (O), or sham control (placement of electrodes without electro-acupoint stimulation; placebo [P]). The anesthetic regimen was standardized. The incidence of nausea, vomiting, rescue antiemetic use, pain, and patient satisfaction with management of PONV were assessed at 0, 30, 60, 90, 120 min, and at 24 h. The complete response (no nausea, vomiting, or use of rescue antiemetic) was significantly more frequent in the active treatment groups compared with placebo both at 2 h (A/O/P = 77%/64%/42%, respectively; P = 0.01) and 24 h postoperatively (A/O/P = 73%/52%/38%, respectively; P = 0.006). The need for rescue antiemetic was less in the treatment groups (A/O/P = 19%/28%/54%; P = 0.04). Specifically, the incidence and severity of nausea were significantly less in the A group compared with the other groups, and in the O group compared with the P group (A/O/P = 19%/40%/79%, respectively). The A group experienced less pain in the postanesthesia care unit, compared with the O and P groups. Patients in the treatment groups were more satisfied with their management of PONV compared with placebo. When used for the prevention of PONV, electro-acupoint stimulation or ondansetron was more effective than placebo with greater degree of patient satisfaction, but electro-acupoint stimulation seems to be more effective in controlling nausea, compared with ondansetron. Stimulation at P6 also has analgesic effects.

New and dis-improved: on the evaluation and use of less effective, less expensive medical interventions

The innovation and diffusion of new technologies is in large measure responsible for the persistent rise in the cost of health care. The increasing cost of health care, in turn, will make cost-saving technologies more attractive. When cost-saving technologies lead to better or equivalent outcomes, their acceptance will not be controversial. However, the necessary conditions for the development and clinical acceptance of cost-saving technologies that might diminish the quality of health care have not been systematically considered. Indeed, as the clinical research enterprise has been focused almost entirely on quality-improving (or quality-neutral) innovations, new concepts may need to be introduced for quality-reducing innovations. Although the development of such therapies would, at least in some circumstances, increase overall societal benefits, replacing a standard therapy with a less effective one may conflict with deeply held values, such that conventional cost-effectiveness benchmarks might not apply. In addition, from a clinical research perspective, there are considerable ethical and methodologic hurdles that might impede the development of less expensive, less intensive therapies. In this article, using a hypothetical scenario, the authors consider economic, ethical, and research design issues concerning the innovation and diffusion of less effective, less expensive therapies and introduce 2 concepts--"decremental cost-effectiveness" and "acceptability trials"--that may in part provide a research framework for the study of "new and dis-improved" therapies.

Equivalence and noninferiority trials - are they viable alternatives for registration of new drugs? (III)

The scientific community's reliance on active-controlled trials is steadily increasing, as widespread agreement emerges concerning the role of these trials as viable alternatives to placebo trials. These trials present substantial challenges with regard to design and interpretation as their complexity increases, and the potential need for larger sample sizes impacts the cost and time variables of the drug development process. The potential efficacy and safety benefits derived from these trials may never be demonstrated by other methods. Active-controlled trials can develop valuable data to inform both prescribers and patients about the dose- and time-dependent actions of any new drug and can contribute to the management and communication of risks associated with the relevant therapeutic products.

Prophylactic respiratory physiotherapy after cardiac surgery: systematic review

OBJECTIVE

To assess whether respiratory physiotherapy prevents pulmonary complications after cardiac surgery.

DATA SOURCES

Searches through Medline, Embase, Cinahl, the Cochrane library, and bibliographies, for randomised trials comparing any type of prophylactic respiratory physiotherapy with another type or no intervention after cardiac surgery, with a follow up of at least two days, and reporting on respiratory outcomes.

REVIEW METHODS

Investigators assessed trial validity independently. Information on study design, population, interventions, and end points was abstracted by one investigator and checked by the others.

RESULTS

18 trials (1457 patients) were identified. Most were of low quality. They tested physical therapy (13 trials), incentive spirometry (eight), continuous positive airway pressure (five), and intermittent positive pressure breathing (three). The maximum follow up was six days. Four trials only had a no intervention control; none showed any significant benefit of physiotherapy. Across all trials and interventions, average values postoperatively were: incidence of atelectasis, 15-98%; incidence of pneumonia, 0-20%; partial pressure of arterial oxygen per inspired oxygen fraction, 212-329 mm Hg; vital capacity, 37-72% of preoperative values; and forced expiratory volume in one second, 34-72%. No intervention showed superiority for any end point. For the most labour intensive intervention, continuous positive airway pressure, the average cost of labour for each patient day was 27 euro (pound 19; 32 dollars).

CONCLUSIONS

The usefulness of respiratory physiotherapy for the prevention of pulmonary complications after cardiac surgery remains unproved. Large randomised trials are needed with no intervention controls, clinically relevant end points, and reasonable follow up periods.

Active-control clinical trials to establish equivalence or noninferiority: methodological and statistical concepts linked to quality

The randomized, double-blind, placebo-controlled trial is the optimum method for clinical evaluation of new treatments, as assessed by clinicians and statisticians. However, if a known standard of therapy exists, it may be difficult to prove that a new therapy is superior. Equivalence and noninferiority clinical trial designs are now frequently utilized in clinical medical research. This article reviews the statistical differences between superiority, equivalence, and noninferiority design schemes, which pose specific ethical questions and have important implications for interpretation and clinical application of trial results. A guideline is proposed as a standard approach for reporting to facilitate qualitative assessment of the methodology of these trials.

Dexamethasone is as effective as ondansetron for the prevention of postoperative nausea and vomiting following breast surgery

INTRODUCTION

Postoperative nausea and vomiting remain a common problem following breast surgery. This study assesses whether dexamethasone is as effective as ondansetron in the control of postoperative nausea and vomiting (PONV).

METHODS

Eighty ASA I-III patients undergoing breast surgery for carcinoma of the breast were included in the study. Following premedication with diazepam 5-10 mg, patients were induced with fentanyl 50 micro g and propofol 2-2.5 mg kg-1. A larynx mask was inserted and anesthesia maintained with sevoflurane in oxygen and nitrous oxide. Patients were then randomly divided into two groups: Group D (dexamethasone) was given 4 mg dexamethasone i.v. after induction and Group O (ondansetron) was given 4 mg ondansetron at the same time point. Postoperatively, nausea, vomiting and pain were recorded at 1-h intervals during 4 h, and thereafter every 4 h during 24 h.

RESULTS

The incidence of PONV during 24 h was 37% and 33% in Group D and Group O, respectively (NS). No differences were found between the groups in the incidence of postoperative nausea, vomiting or pain at the different time intervals. No differences were found in the incidence of PONV in smokers vs. non-smokers. No side-effects of these drugs were observed.

CONCLUSIONS

Ondansetron 4 mg or dexamethasone 4 mg are equally effective in the prevention of postoperative nausea and vomiting following breast surgery. Other factors being similar, the difference in cost between these drugs would favor the use of dexamethasone instead of ondansetron when monotherapy against PONV is used.

Benefits and risks of newer treatments for chemotherapy-induced and postoperative nausea and vomiting

Nausea and vomiting are common adverse effects of chemotherapy, radiation therapy, anaesthesia and surgery. The incidence of chemotherapy-induced nausea and vomiting (CINV) is estimated to vary from 30 to 90%, depending on the type of chemotherapeutic agent used. Radiation-induced emesis varies with anatomical site radiated but is estimated to have an overall incidence of approximately 40%. The incidence of postoperative nausea and vomiting (PONV) depends on the type of anaesthesia and surgery, but overall is estimated to be 20-30%. Evidence-based medicine and meta-analysis have been used to direct medical therapy to help determine equivalence, optimal dose, timing, safety and efficacy of antiemetic medications. Concepts such as the number needed to treat and number needed to harm are helpful to guide the clinician regarding the benefits and risks of a particular treatment. The serotonin 5-HT(3) receptor antagonists ondansetron, granisetron, tropisetron and dolasetron have been important additions to the antiemetic armamentarium. The 5-HT(3) receptor antagonists are similar in chemical structure, efficacy and adverse effect profile. They appear to have no important differences among themselves in clinical outcomes for CINV and PONV. Headache, dizziness, constipation and diarrhoea are their most common adverse effects, and when they occur they are usually mild and easily managed. Haemodynamic changes and extrapyramidal adverse effects are uncommon. ECG changes such as prolonged corrected QT (QTc) interval are infrequent, dose-related and overall judged to be clinically insignificant. As most studies with the 5-HT(3) antagonists have been conducted on relatively healthy patients, caution should be exercised when these drugs are used in susceptible patients with co-morbidities. The clinician must weigh the benefit of administering an antiemetic for CINV or PONV against the risk of occurrence of an adverse event.

Issues in the conduct of therapeutic trials in palliative care: an Australian perspective

Palliative care has been slow to demonstrate that its common interventions are supported by high levels of evidence. There are multiple reasons for this--historical and cultural, as well as the recognised difficulties of conducting studies in dying persons. There are problems in isolating the effect of a single intervention from the many other changing dimensions which attend the progress of terminal illness, and problems also in defining particular outcomes free from the contaminating effect of other simultaneous changes in a patient's situation. Sickness is an interaction between disease and patient, and science sits more comfortably with the study of disease than with the understanding of the patient. Nevertheless, the therapies commonly employed for symptom management in individuals with advanced and terminal illness deserve more rigorous investigation to establish their efficacy. In Australia, new levels of government support for research have stimulated a closer examination of principles and practical guidelines for the conduct of research in this area of healthcare.

Reflections and recommendations on research ethics in developing countries

The debate on the ethics of international clinical research involving collaboration with developing countries has achieved a high profile in recent years. Informed consent and universal standards have been most intensively debated. Exploitation and lack of adequate attention to justice in the distribution of risks/harm and benefits to individuals and communities have to a lesser extent been addressed. The global context in which these debates are taking place, and some of the less obvious implications for research ethics and for health are discussed here to broaden understanding of the complexity of the debate. A wider role is proposed for research ethics committees, one that includes an educational component and some responsibility for audit. It is proposed that new ways of thinking are needed about the role of research ethics in promoting moral progress in the research endeavour and improving global health.

Placebos, placebo effect, and the response to the healing situation: the evolution of a concept

In spite of its impressive progress, medicine has been strongly criticized for relying on its modern biomedical tradition to the neglect of the psychosocial aspects of health. This neglect may account for patients' dissatisfaction and eventual use of alternative health approaches. The concept of placebo has sustained dramatic "protean" metamorphoses through the ages. For centuries, placebos have been regarded as powerful deceptive therapies. From the middle of the twentieth century, however, conventional medicine has used placebos as methodologic tools to distinguish the specific from the nonspecific ingredients in treatments. In modern medical research, the double-blind, placebo-controlled, randomized clinical trial has been established as the gold standard for the assessment of any new treatment. Recently a new trend regarding placebos seems to have emerged. The placebo and other nonspecific effects elicited by the "healing situation" have been independently subjected to scientific study. Progress in this area may promote useful clinical applications, enabling physicians to broaden their perspectives on the healing process. We present the historical changes of the concept of placebo and the ethical issues raised by their use.

Active-control equivalence trials and antihypertensive agents

PURPOSE

To identify methodological features that affect the validity of conclusions drawn from active-control equivalence trials and to apply these criteria to recently published trials comparing antihypertensive agents from different classes.

METHODS

Standard methodological criteria for randomized clinical trials and six additional methodological features that affect the validity of active-control equivalence trials were applied to four recently published large trials that compared different antihypertensive classes and that concluded that their results showed equivalence.

RESULTS

All four of these trials fulfilled standard criteria for randomized trials. However, none fulfilled all of the six additional methodological criteria that affect the validity of active-control equivalence trials, one fulfilled five criteria, two fulfilled two criteria, and one failed to fulfill any of the criteria.

CONCLUSION

Standard methodological criteria for evaluating superiority trials are inadequate for the interpretation of active-control equivalence trials. The methodological criteria outlined in this article for judging the validity of active-control equivalence trials are not specific to antihypertensive trials and may be applied to trials that test a wide variety of interventions.

Treatment of established postoperative nausea and vomiting: a quantitative systematic review

BACKGROUND: The relative efficacy of antiemetics for the treatment of postoperative nausea and vomiting (PONV) is poorly understood. METHODS: Systematic search (MEDLINE, Embase, Cochrane Library, bibliographies, any language, to 8.2000) for randomised comparisons of antiemetics with any comparator for the treatment of established PONV. Dichotomous data on prevention of further nausea and vomiting, and on side effects were combined using a fixed effect model. RESULTS: In seven trials (1,267 patients), 11 different antiemetics were tested without placebos; these data were not further analysed. Eighteen trials (3,809) had placebo controls. Dolasetron 12.5-100 mg, granisetron 0.1-3 mg, tropisetron 0.5-5 mg, and ondansetron 1-8 mg prevented further vomiting with little evidence of dose-responsiveness; with all regimens, absolute risk reductions compared with placebo were 20%-30%. The anti-nausea effect was less pronounced. Headache was dose-dependent. Results on propofol were contradictory. The NK1 antagonist GR205171, isopropyl alcohol vapor, metoclopramide, domperidone, and midazolam were tested in one trial each with a limited number of patients. CONCLUSIONS: Of 100 vomiting surgical patients receiving a 5-HT3 receptor antagonist, 20 to 30 will stop vomiting who would not have done so had they received a placebo; less will profit from the anti-nausea effect. There is a lack of evidence for a clinically relevant dose-response; minimal effective doses may be used. There is a discrepancy between the plethora of trials on prevention of PONV and the paucity of trials on treatment of established symptoms. Valid data on the therapeutic efficacy of classic antiemetics, which have been used for decades, are needed.

Randomised crossover trial of transdermal fentanyl and sustained release oral morphine for treating chronic non-cancer pain

OBJECTIVES

To compare patients' preference for transdermal fentanyl or sustained release oral morphine, their level of pain control, and their quality of life after treatment.

DESIGN

Randomised, multicentre, international, open label, crossover trial.

SETTING

35 centres in Belgium, Canada, Denmark, Finland, the United Kingdom, the Netherlands, and South Africa.

PARTICIPANTS

256 patients (aged 26-82 years) with chronic non-cancer pain who had been treated with opioids.

MAIN OUTCOME MEASURES

Patients' preference for transdermal fentanyl or sustained release oral morphine, pain control, quality of life, and safety assessments.

RESULTS

Of 212 patients, 138 (65%) preferred transdermal fentanyl, whereas 59 (28%) preferred sustained release oral morphine and 15 (7%) expressed no preference. Better pain relief was the main reason for preference for fentanyl given by 35% of patients. More patients considered pain control as being "good" or "very good" with fentanyl than with morphine (35% v 23%, P=0.002). These results were reflected in both patients' and investigators' opinions on the global efficacy of transdermal fentanyl. Patients receiving fentanyl had on average higher quality of life scores than those receiving morphine. The incidence of adverse events was similar in both treatment groups; however, more patients experienced constipation with morphine than with fentanyl (48% v 29%, P<0.001). Overall, 41% of patients experienced mild or moderate cutaneous problems associated with wearing the transdermal fentanyl patch, and more patients withdrew because of adverse events during treatment with fentanyl than with morphine (10% v 5%). However, within the subgroup of patients naive to both fentanyl and morphine, similar numbers of patients withdrew owing to adverse effects (11% v 10%, respectively).

CONCLUSION

Transdermal fentanyl was preferred to sustained release oral morphine by patients with chronic non-cancer pain previously treated with opioids. The main reason for preference was better pain relief, achieved with less constipation and an enhanced quality of life.