The ethics of using placebo in hypertension clinical trials

Clinical trials of antihypertensives: Nature of control and design

This paper reviews the critical issues in the control and design of antihypertension (anti-HT) clinical trials. The international guidelines and current clinical and biostatistical practices were reviewed for relevant clinical, design, end-point assessments and regulatory issues. The results are grouped mainly into ethical, protocol and assessment issues. Ethical issues arise as placebo-controlled trials (PCTs) for HT-lowering agents in patients with moderate to severe HT are undertaken. Patients with organ damage due to HT should not be included in long-term PCT. Active-control trials, however, are suitable for all randomized subsets of patients, including men and women, and different ethnic and age groups. Severity subgroups must be studied separately with consideration to specific study design. Mortality and morbidity outcome studies are not required in anti-HT trials except when significant mortality and cardiovascular morbidity are suspected. Generally, changes in both systolic and diastolic blood pressures (BP) at the end of the dosing interval from the baseline are compared between the active and the control arms as the primary endpoint of anti-HT effect. Onset of the anti-HT effect can be studied as the secondary endpoint. For maintenance of efficacy, long-term studies of ≥6 months need to be undertaken. Error-free measurement of BP is a serious issue as spontaneous changes in BP are large and active drug effect on diastolic BP is often small. Placebo-controlled short-term studies (of ~12 weeks) for dose-response and titration are very useful. Safety studies must be very vigilant on hypotension, orthostatic hypotension and effects on heart. In dose-response studies, at least three doses in addition to placebo should be used to well characterize the benefits and side-effects.

Can we justify goal blood pressure of <140/90 mm hg in most hypertensives?

Hypertension is a common disorder with well-recognized consequences on the heart, brain, and kidney as target organs. Guidelines espouse a treatment goal of blood pressure reduction to <140 mm Hg for the systolic pressure and <90 mm Hg for the diastolic pressure in most hypertensive patients. In this review, the basis for these recommendations, the practical achievement of these goals in various practice settings, and the risk versus the benefit of achieving such goals in most hypertensive patients are examined.

The revision of the Declaration of Helsinki: past, present and future

The World Medical Association's Declaration of Helsinki was first adopted in 1964. In its 40-year lifetime the Declaration has been revised five times and has risen to a position of prominence as a guiding statement of ethical principles for doctors involved in medical research. The most recent revision, however, has resulted in considerable controversy, particularly in the area of the ethical requirements surrounding placebo-controlled trials and the question of responsibilities to research participants at the end of a study. This review considers the past versions of the Declaration of Helsinki and asks the question: How exactly has the text of the Declaration changed throughout its lifetime? Regarding the present form of the Declaration of Helsinki we ask: What are the major changes in the most recent revision and what are the controversies surrounding them? Finally, building on the detailed review of the past and present versions of the Declaration of Helsinki, we give consideration to some of the possible future trajectories for the Declaration in the light of its history and standing in the world of the ethics of medical research.

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.

Effect of Omacor on HRV parameters in patients with recent uncomplicated myocardial infarction - A randomized, parallel group, double-blind, placebo-controlled trial: study design [ISRCTN75358739]

BACKGROUND: A large body of data derived from animal, epidemiological and clinical studies indicate that n-3 polyunsaturated fatty acids have a favourable effect on the prognosis of patients with cardiovascular disease in general, and on reducing sudden death in particular.Depressed heart rate variability (HRV), an indicator of impairment of the autonomic nervous system, has been shown to be a powerful predictor of subsequent mortality in patients surviving an acute myocardial infarction. A multitude of studies have demonstrated this strong association, suggesting that the imbalance in the sympathic/parasympathetic system may facilitate emergence of ventricular arrhythmias.Heart rate variability parameters will be assessed in the present study, with the primary objective of evaluating the possible superiority of Omacor (a highly refined, concentrated omega-3 fatty acid) versus placebo in improving HRV from baseline to endpoint in patients with recent uncomplicated myocardial infarction. Both groups will receive optimal conventional treatment.The study will also explore and quantify improvement in time domain HRV indices and will assess the safety of administering Omacor to optimally treated post-infarction patients (conventional treatment). METHODS: This multi-centre study will evaluate the effect of Omacor 1 g, o.d. on time-domain HRV parameters in comparison to placebo o.d. in patients with recent uncomplicated transmural myocardial infarction.Patients will be screened during the first few days after the acute event as appropriate for the patient's condition, and after obtaining informed consent. Based on inclusion/exclusion criteria, a first 24-hour Holter recording will be performed. Two to five days later, screened patients still eligible for the study will undergo a second 24-hour Holter recording. After the second Holter recording, all patients will be randomly allocated to treatment with Omacor 1 g, o.d. or placebo o.d.One hundred patients will be followed in double-blind fashion for a six-month period after randomization. Visits, including 24-hour Holter recording and assessment of adverse events, will take place at one-month intervals +/- five days after randomization, i.e., six times in all.

Ethics of placebo use in pediatric clinical trials: the case of antihypertensive drug studies

Industry-sponsored pediatric clinical trials of antihypertensive medications have greatly increased in number since passage of the Food and Drug Modernization Act of 1997. This development should ultimately benefit the treatment of hypertensive children by increasing the amount of scientific knowledge regarding the efficacy and safety of antihypertensive agents in children. However, the designs of many of these trials raise ethical questions related to the inclusion of placebo controls, a practice that has largely been abandoned in trials of antihypertensives in adults because of the well-known adverse consequences of untreated hypertension. This is an especially important issue in pediatric hypertension, as many hypertensive children have either secondary forms of hypertension or hypertension-induced target organ damage, potentially increasing the risk of harm during exposure to placebo. Against this background, and with a strong emphasis on protection of this vulnerable patient population, a strict set of conditions for use of placebos in pediatric antihypertensive trials is proposed.

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

OBJECTIVE

To evaluate physicians' preferences for referring patients to, and using information from, active-controlled trials (ACTs) versus placebo-controlled trials (PCTs) of new antihypertensive drugs.

DESIGN AND SETTING

Nationwide mailed survey, with telephone contact of nonresponders to assess nonresponse bias.

PARTICIPANTS

One thousand two hundred primary care physicians randomly selected from the American Medical Association's Master File. Of 1,154 physicians eligible to respond, 651 (56.4%) returned completed questionnaires.

MEASUREMENTS AND MAIN RESULTS

We measured physicians' stated willingness to encourage hypertensive patients to enroll in ACTs and PCTs of new antihypertensive drugs, their views of the relative merits of ACTs versus PCTs, their stated willingness to prescribe new drugs tested in ACTs or PCTs, and their views regarding the overall justifiability of the 2 designs. Physicians were significantly more likely to indicate they would encourage their patients to enroll in ACTs than in PCTs (P <.0001). Physicians thought ACTs provided more valuable information for their practices, were more likely to lead to a public health benefit, offered enrolled patients greater opportunity for personal benefit, and were less likely to expose enrolled patients to unnecessary risks (all P <.0001). Physicians were more likely to prescribe new drugs that had been compared in ACTs (P <.0001), and viewed ACTs as a more justifiable method for testing new antihypertensive drugs (P <.0001). There was no evidence of nonresponse bias for these main results.

CONCLUSIONS

Although PCTs remain the standard method for testing new antihypertensive drugs, physicians strongly prefer ACTs. Using ACTs to test new antihypertensive drugs may enhance the efficiency of patient recruitment and more strongly influence physicians' prescribing practices.

Efficient trial designs to reduce placebo requirements

This brief discussion summarizes possible trial design changes that could be utilized to reduce the number of subjects exposed to ineffective treatment--in this case placebo; however, these designs are fairly complex and have not been implemented sufficiently to judge their utility. Clearly, such studies are essential before embarking on these paradigms as a primary method for assessing antidepressant efficacy.