Physicians' preferences for active-controlled versus placebo-controlled trials of new antihypertensive drugs

Historical Controls in Randomized Clinical Trials: Opportunities and Challenges

Randomized control trials (RCTs) with placebo are the gold standard for determining efficacy of novel pharmaceutical treatments. Since their inception, over 75 years ago, researchers have amassed a large body of underutilized data on outcomes in the placebo control arms of these trials. Although rare disease indications have used these historical placebo data as synthetic controls to reduce burden on patients and accelerate drug discovery, broad use of historical controls is in its infancy. Large-scale historical placebo data could be leveraged to benefit both drug developers and patients if warehoused and made more available to guide trial design and analysis. Here, we examine challenges in utilizing historical controls related to heterogeneity in trial design, outcome ascertainment, patient characteristics, and unmeasured pharmacogenomic effects. We then discuss the advantages and disadvantages of current approaches and propose a path forward to broader use of historical controls in RCTs.

Head-to-head trials of systemic psoriasis therapies: a systematic review of study design and maximum acceptable treatment differences

There is increasing use of head-to-head clinical trials in dermatology when establishing the efficacy of a new treatment. Active comparator trials (ACTs) can be classified into three distinct study trial designs: non-inferiority, equivalence and superiority. A better understanding of the statistical parameters, such as acceptable treatment differences (also known as the margin or delta), is necessary to properly design and interpret findings of active comparator trials (ACTs) in the field of dermatology. Therefore, the objective of this study was to summarize the maximum acceptable treatment differences in clinical trials that examine the efficacy of an oral or biologic psoriasis therapy with an active comparator. We conducted a systematic search using MEDLINE, Scopus, EMBASE, Cochrane Central Register of Controlled Trials, LILACS, Web of Science and ClinicalTrials.gov from inception to 31 August 2017. All ACTs with adult participants that had a primary outcome of the Psoriasis Area and Severity Index score were included. Bibliographies of articles were further reviewed. Two investigators independently assessed for article inclusion and separately completed data extraction of predefined data points. When there was a disagreement, a third investigator was consulted. Of the 49 ACTs included, there were 13 superiority, eight non-inferiority and seven equivalence trials. Another 21 studies had inadequate information for classification. All of the non-inferiority trials reported the margin, one of the superiority and six of the equivalence trials stated the treatment difference explicitly. For superiority trials, acceptable treatment differences ranged from 14% to 20%. The non-inferiority studies reported lower bound margins ranging from -20% to -10%. The equivalence trials reported upper and lower bound margins ranging from ±12.5% to ±18%. The results demonstrate the need for harmonization in the conduct of dermatological clinical trials and in the approaches of reporting research parameters.

Systemic Sclerosis Trial Design Moving Forward

The 2013 ACR-EULAR classification criteria for systemic sclerosis (SSc) have shifted the construct of SSc. The new reality is that patients recruited for trials may not be so severe and not so advanced. We can now look for therapeutics that might stop disease evolution and/or prevent organ involvement. This article highlights recent advances in research methodology, and broadens the potential range of design and analytic considerations when planning a SSc trial.

The challenges of control groups, placebos and blinding in clinical trials of dietary interventions

High-quality placebo-controlled evidence for food, nutrient or dietary advice interventions is vital for verifying the role of diet in optimising health or for the management of disease. This could be argued to be especially important where the benefits of dietary intervention are coupled with potential risks such as compromising nutrient intake, particularly in the case of exclusion diets. The objective of the present paper is to explore the challenges associated with clinical trials in dietary research, review the types of controls used and present the advantages and disadvantages of each, including issues regarding placebos and blinding. Placebo-controlled trials in nutrient interventions are relatively straightforward, as in general placebos can be easily produced. However, the challenges associated with conducting placebo-controlled food interventions and dietary advice interventions are protean, and this has led to a paucity of placebo-controlled food and dietary advice trials compared with drug trials. This review appraises the types of controls used in dietary intervention trials and provides recommendations and nine essential criteria for the design and development of sham diets for use in studies evaluating the effect of dietary advice, along with practical guidance regarding their evaluation. The rationale for these criteria predominantly relate to avoiding altering the outcome of interest in those delivered the sham intervention in these types of studies, while not compromising blinding.

Collective Equipoise, Disappointment, and the Therapeutic Misconception: On the Consequences of Selection for Clinical Research

Private information induces individuals to self-select as subjects into clinical research trials, and it induces researchers to select which trials they conduct. The authors show that selection can induce ex ante therapeutic misconception and ex post disappointment among research subjects, and it undermines the rationale of collective equipoise as an ethical basis for clinical trials. Selection provides a reason to make nontrivial payments to subjects, and it implies that researchers should not design experiments to maximize statistical power.

The placebo response of injectable GLP-1 receptor agonists vs. oral DPP-4 inhibitors and SGLT-2 inhibitors: a systematic review and meta-analysis

AIMS

The size of the placebo response in type 2 diabetes (T2DM) treatment and its relation to the route of drug administration have not been systematically reviewed. We aimed to determine weight loss, change in HbA1c and incidence of adverse events after treatment with injectable placebo GLP-1 receptor agonist (GLP-1ra), compared with oral placebo DPP-4 inhibitor (DPP-4i) and placebo SGLT-2 inhibitor (SGLT-2i).

METHODS

PubMed, EMBASE and Central were searched up to September 2014 for randomized placebo controlled trials investigating GLP-1ra, DPP-4i or SGLT2-i. Data on placebo groups were extracted and pooled using a generic inverse variance random effects model.

RESULTS

Sixty-seven trials were included, involving 2522, 5290 and 2028 patients randomized to placebo GLP-1ra, placebo DPP-4i and placebo SGLT-2i, respectively. Body weight decreased by -0.67 kg (95% CI -1.03, -0.31) after treatment with placebo GLP-1ra (-0.76 kg [95% CI -1.10, -0.43] with placebo short acting GLP-1ra and -0.32 kg [95% CI -1.75, 1.10] with placebo long acting GLP-1ra) and by -0.31 kg (95% CI -0.64, 0.01) with placebo DPP-4i (P = 0.06 for difference with placebo short acting GLP-1ra). Placebo SGLT-2i resulted in an intermediate -0.48 kg (95% CI -0.81, -0.15) weight loss. Weight loss with placebo showed a strong correlation with the active comparator drug (r(2)  = 0.40-0.78). HbA1c changed little with placebo treatment (-0.23%, 0.10% and -0.13% for placebo GLP-1ra, DPP-4i and SGLT-2i). Adverse events occurred frequently with placebo, were often similar to the active comparator drug and led to drop-out in 2.0-2.7% of cases.

CONCLUSIONS

The response to placebo treatment was related to its active comparator, with injectable placebo GLP-1ra showing a relevant response on weight, whereas oral placebo DPP4i showed no significant response. These findings may suggest that subjective expectations influence T2DM treatment efficacy, which can possibly be employed therapeutically.

Placebo-controlled clinical trials: how trial documents justify the use of randomisation and placebo

BACKGROUND

Randomised clinical trials (RCTs) involve procedures such as randomisation, blinding, and placebo use, which are not part of standard medical care. Patients asked to participate in RCTs often experience difficulties in understanding the meaning of these and their justification.

METHODS

We reviewed RCT protocols, statements of the principal investigator (PI), and participant-information materials, as submitted for opinion to a research ethics committee. We evaluated how the justification for the use of placebo was described in these documents and how the participants had been informed about randomisation, placebo use, and the possible risks of receiving placebo.

RESULTS

In total, 52 RCTs were identified. Eighteen of the study protocols (35%) provided some rationale for the use of placebo. In 15 (29%) of the statements, the PI had provided justification for its use. Possible risks related to placebo use were described in nine (17%) of the statements. An explanation as to why placebo was necessary featured in only 12 (23%) of the sets of participant-information materials, and only six (12%) of the documents discussed the possible risks associated with placebo.

CONCLUSIONS

The justification of placebo control was inadequately described in the RCT study protocols, by principal or national co-ordinating investigators, and in participant-information documents. Furthermore, possible health-related risks associated with the use of placebo were poorly explained in the participant-information documents. Ethics committes and study participants need to be better informed of the rationale for the use of placebo, along with the associated risks.

Geometry of the randomized evidence for treatments of pulmonary hypertension

OBJECTIVE

We studied the entire agenda of randomized clinical trials in pulmonary hypertension (PH) using sociological methods. We explored the geometry of the PH network to interpret the evidence on multiple competing treatments for the same indication.

DESIGN

We searched MEDLINE, Embase and Cochrane Library Databases for published studies. We queried clinicaltrials.gov and WHO International Clinical Trials Registry platform for non-published studies.

RESULTS

We found 75 randomized trials (41 published [n = 4136 participants] and 34 registered unpublished [planned n = 3470 participants]). Of the published randomized studies, all used placebo as the comparator arm except for two nonindustry-sponsored comparisons between phosphodiestearase-5 (PDE-5) inhibitors and endothelin receptor antagonists (ERA), and one study comparing two different regimens of treprostinil. Similarly, only five unpublished/ongoing trials used an active PH treatment as comparator (PDE-5 inhibitors versus ERA (n = 3), different doses of sildenafil (n = 1) and two formulations of epoprostenol (n = 1). Of the 75 trials, 47 were sponsored by the manufacturer of the tested active product(s), and only two trials were sponsored by two companies comparing their products.

CONCLUSIONS

The relative merits of different treatment options are not directly known, as there are very few head-to-head comparisons. A limited number of ongoing studies are using active FDA-approved PH-treatments for comparison. This lack of information can be overcome by carefully designing comparative effectiveness trials.

A web-based patient activation intervention to improve hypertension care: study design and baseline characteristics in the web hypertension study

BACKGROUND

Despite the known health risks of hypertension, many hypertensive patients still have uncontrolled blood pressure. Clinical inertia, the tendency of physicians not to intensify treatment, is a common barrier in controlling chronic diseases. This trial is aimed at determining the impact of activating patients to ask providers to make changes to their care through tailored feedback.

METHODS

Diagnosed hypertensive patients were enrolled in this RCT and randomized to one of two study groups: (1) the intervention condition--Web-based hypertension feedback, based on the individual patient's self-report of health variables and previous BP measurements, to prompt them to ask questions during their next physician's visit about hypertension care (2) the control condition--Web-based preventive health feedback, based on the individual's self-report of receiving preventive care (e.g., pap testing), to prompt them to ask questions during their next physician's visit about preventive care. The primary outcome of the study is change in blood pressure and change in the percentage of patients in each group with controlled blood pressure.

CONCLUSION

Five hundred participants were enrolled and baseline characteristics include a mean age of 60.0 years; 57.6% female; and 77.6% white. Overall 37.7% participants had uncontrolled blood pressure; the mean body mass index (BMI) was in the obese range (32.4) and 21.8% had diabetes. By activating patients to become involved in their own care, we believe the addition of the web-based intervention will improve blood pressure control compared to a control group who receive web-based preventive messages unrelated to hypertension.

Developments in post-marketing comparative effectiveness research

Physicians and insurers need to weigh the effectiveness of new drugs against existing therapeutics in routine care to make decisions about treatment and formularies. Because Food and Drug Administration (FDA) approval of most new drugs requires demonstrating efficacy and safety against placebo, there is limited interest by manufacturers in conducting such head-to-head trials. Comparative effectiveness research seeks to provide head-to-head comparisons of treatment outcomes in routine care. Health-care utilization databases record drug use and selected health outcomes for large populations in a timely way and reflect routine care, and therefore may be the preferred data source for comparative effectiveness research. Confounding caused by selective prescribing based on indication, severity, and prognosis threatens the validity of non-randomized database studies that often have limited details on clinical information. Several recent developments may bring the field closer to acceptable validity, including approaches that exploit the concepts of proxy variables using high-dimensional propensity scores, within-patient variation of drug exposure using crossover designs, and between-provider variation in prescribing preference using instrumental variable (IV) analyses.

[Perceptions of patients and physicians involved in clinical trials: an overview of the literature]

OBJECTIVE - METHOD: The purpose of this review is to explore the expectations of patients and physicians prior to participate to a clinical trial and their positive or negative experiences after participating. A systematic review of Medline database from 1966 to 2005 identified 79 papers reported patients and physicians perceptions of clinical trials (only 3 in French), whom 27 English surveys conducted on patients and physicians.

RESULTS

If primary patients' motivation for enrolment was altruistic, physicians wish to help their patient. After enrolment, the most perceived positive benefit for patients and physicians are, respectively, the emotional improvement and the greater opportunity for personal benefit offered to enrolled patients. Most physicians' negative experience included logistical difficulties while patients are unease with randomisation and often uncomfortable with medical procedures. Unlike patients, all physicians' expectations seem to be fulfilled.

CONCLUSION

The knowledge of patients' and physicians' perception of participation may improve recruitment in clinical trials.

Simultaneous assessment of short-term gastrointestinal benefits and cardiovascular risks of selective cyclooxygenase 2 inhibitors and nonselective nonsteroidal antiinflammatory drugs: An instrumental variable analysis

OBJECTIVE

To simultaneously assess the short-term reduction in risk of gastrointestinal (GI) complications and increase in risk of acute myocardial infarction (MI) by celecoxib compared with rofecoxib and several nonselective nonsteroidal antiinflammatory drugs (NSAIDs) using instrumental variable analysis.

METHODS

A population of 49,711 Medicare beneficiaries ages 65 years and older who initiated nonselective NSAID or selective cyclooxygenase 2 inhibitor therapy between January 1, 1999, and December 31, 2002, was identified. The increase in risk of GI complications and MI within 180 days after initiation of NSAID (rofecoxib, diclofenac, ibuprofen, and naproxen compared with celecoxib) therapy was assessed using instrumental variable analysis.

RESULTS

Compared with nonselective NSAIDs, celecoxib reduced the risk of GI complications by 1.4 per 100 users but increased the risk of MI by 0.3 per 100 users. Rofecoxib decreased GI complications by 1.1 per 100 users and increased the risk of MI by 0.3 per 100 users. Using celecoxib as the reference exposure showed an increase in the MI risk for rofecoxib (risk difference [RD] 1.40, 95% confidence interval [95% CI] -0.20, 3.01) and diclofenac (RD 6.07, 95% CI -0.02, 12.15). The RD for naproxen as well as its upper 95% CI was the lowest of all NSAIDs (RD -0.30, 95% CI -2.74, 2.14) and there was no significant difference in GI complication rates among all NSAIDs.

CONCLUSION

In this instrumental variable analysis, diclofenac and rofecoxib had the least favorable benefit-risk balance among NSAIDs in older adults.

Clinical trials in children

The imperative to undertake randomised trials in children arises from extraordinary advances in basic biomedical sciences, needing a matching commitment to translational research if child health is to reap the benefits from this new knowledge. Unfortunately, many prescribed treatments for children have not been adequately tested in children, sometimes resulting in harmful treatments being given and beneficial treatments being withheld. Government, industry, funding agencies, and clinicians are responsible for research priorities being adult-focused because of the greater burden of disease in adults, coupled with financial and marketing considerations. This bias has meant that the equal rights of children to participate in trials has not always been recognised. This is changing, however, as the need for clinical trials in children has been increasingly recognised by the scientific community and broader public, leading to new legislation in some countries making trials of interventions mandatory in children as well as adults before drug approval is given. Trials in children are more challenging than those in adults. The pool of eligible children entering trials is often small because many conditions are uncommon in children, and the threshold for gaining consent is often higher and more complex because parents have to make decisions about trial participation on behalf of their child. Uncertain about what is best, despite supporting the notion of trials in principle, parents and paediatricians generally opt for the new intervention or for standard care rather than trial participation. In this review, we explore issues relating to trial participation for children and suggest some strategies for improving the conduct of clinical trials involving children.

Hypertensive patients' willingness to participate in placebo-controlled trials: implications for recruitment efficiency

BACKGROUND

Underenrollment and selective enrollment plague many clinical trials. Little is known about why hypertensive patients agree or refuse to participate in placebo-controlled trials (PCT) of antihypertensive drugs, whether the prospect of receiving placebo influences willingness to participate (WTP), or whether patients who participate differ from those who do not.

METHODS

We described a hypothetical PCT of a new antihypertensive drug to 126 patients who would be eligible for ongoing phase III trials. We solicited patient motivations and concerns regarding trial participation by using open-ended questions, assessed the patients' stated WTP, and used logistic regression to determine patient characteristics associated with WTP. We reassessed WTP in 62 patients after revealing, in random order, that 10%, 30%, and 50% of patients would receive placebo.

RESULTS

The most commonly cited motivations for participating included personal health benefits (40%), helping other patients (37%), and contributing to scientific knowledge (15%). The most common concerns were having to stop current medications (56%), inconvenience/annoyance (38%), fear of known side effects (35%), and the possibility of receiving placebo (24%). Overall, 47% of patients (95% confidence interval, 38% to 56%) were willing to participate. Younger patients (57% versus 37%; P =.01), nonsmokers (50% versus 24%; P =.04), and patients who had participated in research previously (77% versus 20%; P =.009) were all significantly more willing to participate. Fewer patients were willing to participate as the percentage who would receive placebo increased (P =.02), but randomly assigning fully half of patients to placebo still yielded maximal recruitment efficiency.

CONCLUSIONS

Hypertensive patients participate in trials for altruistic and personal health reasons. Differences between patients who do or do not participate may influence trial outcomes. The proportion of patients receiving placebo influences some patients' enrollment decisions but is not a key determinant of recruitment efficiency.

Using empirical data to inform the ethical evaluation of placebo controlled trials

There has been considerable debate about the ethical acceptability of using placebo-controls in clinical research. Although this debate has been rich in rhetoric, considering that much of this research is predicated upon the assumption that data from this research is vital to clinical decision-making, it is ironic that researchers have introduced little data into these discussions. Using some published research concerning the use of placebo-controls in clinical research in hypertension and psychiatric drug trials, I suggest some ways that such data might be incorporated into the ethical analysis concerning placebo use in clinical trials. This approach promises to be important for enhancing conceptual and scientific understanding as well as public policy decision-making.