«Abstract There is debate regarding the effectiveness of homeopathy and its continuing provision in the NHS, and despite 150+ clinical trials there ...»
A new design for pragmatic randomised
controlled trials: a ‘Patient Cohort’ RCT of
treatment by a homeopath for menopausal
Clare Relton, School of Health and Related Research,
University of Sheffield
PhD Thesis, April 2009
There is debate regarding the effectiveness of homeopathy and its continuing provision in the
NHS, and despite 150+ clinical trials there are conflicting opinions as to what can be concluded
from these trials.
This thesis addresses the question: “What type of clinical trial design can provide the information needed to make decisions about the provision of homeopathy in a publicly funded healthcare system?” A critique of the methods used in existing clinical trial designs was undertaken which identified twelve key criteria for appropriate clinical trial design; methods from existing standard and alternative clinical trial designs were adapted in order to derive a new clinical trial design that has the potential to meet all twelve key criteria (the ‘Patient Cohort’ RCT design).
A current clinical question was identified: ‘What is the clinical & cost effectiveness of treatment by a homeopath for women with menopausal hot flushes?” and a population based survey confirmed the importance of this question. The ‘Patient Cohort’ RCT design was piloted in an NHS setting in order to address this current clinical question.
Seventy ‘with need’ women were recruited to the Hot Flush Cohort of whom forty-eight were eligible for the treatment, a proportion of whom were randomly selected to be offered the treatment. 70.8% of those offered treatment accepted the offer and completion of outcome measures was high (93.7%). The results indicate that a full trial of this treatment for this condition may be worthwhile conducting.
A full RCT using this design would be an appropriate clinical trial design to provide answers as to the provision of homeopathy and other clinician delivered interventions in publicly funded healthcare system such as the NHS. The ‘Patient Cohort’ RCT design can be usefully applied to clinical questions that require very pragmatic approaches yet need the scientific rigour of randomisation.
Chapter 1 Introduction
1.1 The need for clinical trials Worldwide, publicly funded healthcare systems spend vast amounts of money on healthcare with the world’s largest publicly funded health service (the UK’s National Health Service) spending an estimated £98.6 billion for 2008-9 (HM Treasury 2008). Principal fund holders in the NHS are urged to commission healthcare which has the ‘best evidence’ (Sackett et al., 2000a) and advocate that patients should receive treatments which are supported by the most scientifically valid medical research and that evidence from clinical trials and systematic reviews of clinical trials are the highest ranked scientific evidence (Sackett et al., 2000a). Central to this search for the best evidence is the conduct of clinical trials to provide answers to questions which will allow more effective healthcare. Information from clinical trials is required by the publicly funded healthcare systems such as the NHS and the question of the most appropriate clinical trial design is thus an important question.
1.2 Clinical trials and their design
1.2.1 Definitions A clinical trial is defined in the Dictionary of Epidemiology (Last, 2001) as a ‘research activity that involves the administration of a test regimen to humans to evaluate its efficacy and safety’.
Clinical trials are also sometimes called ‘interventional studies’ in order to differentiate them from observational studies where the researchers do not actively manage the experiment.
Medical Subject Headings (MeSH) Terms are the United States National Library of Medicines controlled vocabulary used for indexing articles on MEDLINE/PubMed. MeSH terminology provides a consistent way to retrieve information that may use different terminology for the same concepts (http://www.ncbi.nlm.nih.gov/sites/entrez?db=mesh accessed 2.6.08)
The MeSH definition of ‘clinical trial’ is:
“Pre-planned studies of the safety, efficacy, or optimum dosage schedule (if appropriate) of one or more diagnostic, therapeutic, or prophylactic drugs, devices, or techniques selected according to predetermined criteria of eligibility and observed for predefined evidence of favorable and unfavorable effects”.
1.2.2 Types of trials There are many different types of trials and different ways of classifying and describing trials. A trial can be a controlled trial or a randomised controlled trial (RCT). An RCT is where groups have been formed through random allocation (Torgerson & Torgerson, 2008). The limitation of randomisation is that it is a method based on probability, and therefore one cannot assume that simply because randomisation has been used, that the groups being compared do not differ in terms of any baseline differences which could confound the interpretation of the trial results.
However, the strength of the RCT is that by randomisation, assuming adequate concealment of group allocation, the distribution of any known or unknown prognostic factors at baseline arises purely by chance, thus randomisation is the main method that ensures that allocation bias is eliminated at baseline (Torgerson & Torgerson, 2008).
1.2.3 Purposes of trials Clinical trials are often described in terms of drug therapy, but they can be used to assess any aspect of healthcare. The purpose of a clinical trial can be to identify one or more of the following aspects of any type of healthcare: safety, adverse reactions, mode of action, specific pharmacological effect, optimum dose schedule, efficacy, effects of long term use, cost effectiveness, compliance, acceptability etc. Efficacy is the extent to which a specific intervention, procedure, regimen, or service produces a beneficial result under ‘ideal conditions’. Ideally, the determination of efficacy is based on the results of a randomised controlled trial (RCT) (Last, 2001).
1.2.4 Explanatory trials It can be seen that there are many different types of clinical trial designs, yet the double blind randomised controlled trial has generally been regarded by many as the ‘gold standard’ of clinical trial designs; this type of trial is used to estimate the efficacy of an intervention. In such a trial, the intervention is compared to placebo control and neither the investigator nor the subjects know which treatment is being assigned to whom and the assignments are randomised. These types of trials are also known as ‘explanatory’ trials – they explain whether an intervention is efficacious, i.e. whether it can have a beneficial effect in an ideal situation.
‘An explanatory study is a study whose main objective is to explain rather than merely describe a situation by isolating the effects of specific variables and understanding the mechanisms of action’ (Last, 2001, p66).
Most healthcare trials are explanatory or mechanistic studies (Torgerson & Torgerson, 2008).
The term ‘controlled’ refers to the persons in a comparison group that differs in allocation to a regimen from the subjects of the study (Last, 2001).
1.2.5 Pragmatic trials However, evidence from explanatory trials is uninformative about a range of implementation issues and policy questions e.g. under what conditions the outcomes of the trial can be replicated, whether the interventions are safe, effective and acceptable in routine practice. Thus the need to estimate the ‘effectiveness’ of an intervention in real world clinical practice has given rise to an interest in practice based evidence from either non randomised studies (observational studies) or pragmatic randomised controlled trials. The term pragmatic was first applied to clinical trials by Schwartz & Lellouch (1967) whose seminal work made the distinction between explanatory trials (which aim to further knowledge as to how and why) and pragmatic/practical trials (which aim to inform healthcare decisions within routine practice). The
Dictionary of Epidemiology defines a pragmatic study as a study whose aim is to:
“improve health status or health care of a specified population, provide a basis for decisions about health care, or evaluate previous actions” (Last, 2001, p140).
1.2.6 Publicly funded healthcare systems and clinical trials The primary audience for this thesis is publicly funded healthcare systems. A publicly funded healthcare system is not a single entity or audience, but is made up of many different perspectives. The purpose of this thesis is to search for an appropriate clinical trial design, and this search is examined from a variety of perspectives within a healthcare system (Section 1.9.2). This thesis has taken the UK National Health Service (NHS) as an example of a publicly funded healthcare system and explored the question of appropriate clinical trial design within the context of the NHS. However the questions and answers will be applicable in varying degrees to all publicly funded healthcare systems.
1.2.7 The NHS and clinical trials Clinical trials are designed and conducted to maximise the chance of societal benefit although they are made up of treatments normally intended to be for individual benefit. In the UK, the Department of Health (DH) and its partners have spent many millions of pounds on research regarding the design, methods, operational aspects and evaluation of clinical trials. For example, the DH funded Health Technology Assessment (HTA) Methodology programme has to date funded 44 projects with an estimated total cost of £5.4 million (www.pcpoh.bham.ac.uk/publichealth/nccrm/Portfolio.htm accessed 24.4.08).
Two DH funded sources which the NHS uses to help deliver the best care are The National Institute for Health and Clinical Excellence (NICE) and the National Institute for Health Research (NIHR) Health Technology Assessment (HTA) programme. The National Institute for Health and Clinical Excellence (NICE) was set up in 1999 as a special health authority in the NHS. NICE publishes clinical appraisals of particular treatments for the NHS. These appraisals are based primarily on cost effectiveness and use data primarily from clinical trials. Whereas NICE assesses and evaluates the clinical research information that already exists, there are several organisations which fund research into the best methods for producing and evaluating clinical research information. In England this was the Health Technology Assessment Methodology programme, but this programme, now renamed the Methodology Research Programme, is supported by the Medical Research Council (MRC) and has the aim of supporting the development of methodological tools and theories to underpin health research (www.mrc.ac.uk/ApplyingforaGrant/CallsforProposals).
Homeopathy is currently provided in several publicly funded healthcare systems (UK, Holland, Germany, France, Brazil) and in the UK has been provided in the NHS since its inception in
1948. Homeopathy is defined by the US National Library of Medicine as a:
“A system of therapeutics founded by Samuel Hahnemann (1755-1843), based on the Law of Similars where "like cures like". Diseases are treated by highly diluted substances that cause, in healthy persons, symptoms like those of the disease to be treated. The dilutions are repeated so many times that there is less than one molecule per dose and it is suggested that benefit is from the energetic life force of the original substance.” (http://www.nlm.nih.gov/cgi/mesh/ accessed 1.10.07).
Homeopathy can be delivered in two ways – either by buying over the counter homeopathic remedies or by consulting a homeopath who then prescribes individualised homeopathic remedies. There are two ongoing and sometimes intertwined debates about homeopathy – the efficacy of homeopathic remedies, and the effectiveness and cost effectiveness of the provision of homeopathy.
1.3.1 Debate about homeopathy The efficacy of homeopathic remedies has been a topic of debate since the inception of homeopathy in 1792 and which is still ongoing e.g. currently contradictory conclusions are drawn from the same five meta-analyses of clinical trial evidence of homeopathy (Fisher, 2008;
Goldacre, 2008). In reference to a comparative meta-analysis of homeopathy and allopathy which examined clinical trials of homeopathic remedies (Shang et al., 2005), the editorial of a leading medical journal stated that: “Now doctors need to be bold and honest with their patients about homoeopathy’s lack of benefit.” (Horton, 2005)
1.3.2 Homeopathy and clinical trials
The meta-analysis results change sensitively to the chosen threshold defining large sample sizes thus the results and conclusions are less definite than had been presented (Lütdke & Rutten, 2008). Others have suggested that the results are post hoc rationalisations and that its publication was a result of a breakdown of peer review and standards (Frass, 2005).
Homeopathy has its own tradition of empirical research which represents practice relevant research (provings, evaluations of reactions). Discussions as to clinical trial design for homeopathy are not a new phenomena, as clinical trial design and homeopathy trial design are inextricably linked with the first placebo clinical trials conducted in homeopathic medicines as early as 1829 when bread pills and lactose powders were prescribed as placebos in St Petersburg (Dean, 2004).
Currently homeopathy (and complementary and alternative medicine) researchers have a particular interest in driving debate about how best to evaluate complex healthcare systems as they struggle with demands to meet the standards of evidence based medicine (Boon et al., 2006). In the UK there is a growing realization that if questions as to the validity of NHS provision of homeopathy are to be answered then pragmatic trials of homeopathy are needed.
“Many clinicians are clear that they can now see a role for homeopathy, even if it does perform no better than placebo. I would hope that homeopaths might now divert their attention to performing randomised controlled (albeit unblinded) trials comparing ‘visiting a homeopathy clinic’ against “general practitioner’s treatment as usual”, since this might be the clinical question of more interest to patients i.e. not “do the pills work better than placebo” but “will the experience of visiting a homeopath help me feel better” (Goldacre, 2008)