Sophisticated research design in chiropractic and manipulative therapy; “what you learn depends on how you ask.” Part A. Quantitative research: size does matter

Abstract

Many chiropractors remain sceptical of evidence-based practice (EBP) and some may view it as an attack on the profession which they feel must be resisted. A counter-argument is centred on the primacy afforded quantitative methodology as epitomised by the randomised controlled trial (RCT). This defensive posture may be mitigated by recognising the role complex research has played in the legitimisation of the profession. The pre-eminence of the randomised controlled trial (RCT), considered by many as the gold-standard of evidence, has led some authors to go so far as to functionally disregard all evidence that is not an RCT. However, it is readily apparent the RCT is not always the most appropriate study design to gather evidence, especially in the CAM health sector. This paper discusses the role of sophisticated design in quantitative chiropractic research, presenting examples sequentially through the traditional quantitative hierarchy and concludes that optimal methodology depends on the research question. Research design must allow for the various dimensions of the (chiropractic) clinical encounter, and may be sophisticated at all levels, but must above all, be contextual. The ‘best available’ or most relevant evidence depends on what one needs for a specific purpose. A critical caution is the proviso that care must be exercised not to draw inappropriate conclusions such as causation from descriptive studies.