Complementary Therapiesin Medicine (1997) 5, 90-93 © Pearson Professional Ltd 1997 Evaluating complementary therapies for use in the National Health Service: 'Horses for courses'. Part 1: The design chaHenge M. J. Fitter, K. J. Thomas Foundation for Traditional Chinese Medicine, York and Medical Care Research Unit, University of Sheffield, Sheffield, UK SUMMARY. Despite the amount that has been written about research methodologies for evaluating medical interventions (conventional and non-conventional), there remains a need to clarify which specific research designs are most appropriate and under what circumstances. This paper, the first of two, discusses a number of substantial problems with using a classical randomized controlled clinical trial design for assessing complex interventions, such as many complementary therapies, and identifies a set of design challenges that arise from these problems. In particular, we recognize the need to retain randomization in the research design. Despite the practical difficulties that can arise, the arguments for randomization are compelling. However, we argue for the use of randomization in a way that maximizes the proportion of the population that is included in the evaluation and builds on patients' preferences as much as possible. Additionally, we argue for a design that leaves practitioners free to give individualized treatments as appropriate and enables them to develop their relationship with each patient without constraint. In effect, we want to be able to evaluate the therapy or service delivered under 'normal' service conditions as near as is possible. Our second paper argues that the search for appropriate methods need not be a 'one horse race' and describes two trial designs that appear to meet these challenges without sacrificing methodological rigour. INTRODUCTION Despite the amount that has been written about research methodologies for evaluating medical inter- ventions (conventional and non-conventional) there remains a need to clarify which specific research designs are most appropriate and under what circum- stances. The importance of this issue should not be underestimated, as one commentator has stated 'evaluation which addresses the wrong problems or addresses the right problems badly must run the risk of failing to persuade'.' Vickers 2has summarized the 'methodology debate' in relation to complementary therapies in the UK over the past 10 years, and has mapped out the main 'courses' that must be run. That is, he has identified many of the key research questions and the broad types of research design that can address these ques- tions. Our aim in this paper is to explore some of the assumptions that underpin these research methodolo- gies and to identify their strengths and weaknesses. Mike Fitter, Foundation for TraditionalChineseMedicine, 124 Acomb Road, YorkYO2 4EY,UK. Kate Thomas, SCHARR, Medical Care ResearchUnit, University of Sheffield, Regent Court, 30 RegentStreet, Sheffield S1 4DA, UK. Correspondence to M. Jr.Fitter. That is, to study the 'form' of the 'horses'. In particu- lar, we focus on research designs that may be appropriate for evaluating the potential benefit of introducing complementary therapies within the British National Health Service (NHS). THE CHANGING HEALTH SERVICE CONTEXT Within Western medical culture, the traditional need- to-know question, that can be traced back at least as far as the Hippocratic Oath and which is still at the forefront of any medical practitioner's decision- making, is: What treatment should I offer my patient with this condition? This has led to the formulation of a specific research question which directs empirical research to gather the evidence to answer the need-to-know question. The research question is What is the efficacy of treatment A for condition B? The most appropriate methodology for answering this question is, by general consent, the explanatory 90