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________________________________________ From: Evidence based health (EBH) [[log in to unmask]] on behalf of Juan Gérvas [[log in to unmask]] Sent: 03 August 2016 09:28 To: [log in to unmask] Subject: A +B versus B design, acupunture and more Acupuntura (y otros tratamientos). Diseño de ensayo clínico que lleva a resultados positivos. Acupunture (and others treatment). A trial design that generates only ''positive'' results. In recent years, we have seen a plethora of RCTs adopting a design where patients are randomized to receive either usual care (the control group) or usual care plus the experimental treatment. Schematically this design could be depicted as 'A + B versus B'. At first glance, such comparisons may seem reasonable. However, on closer inspection, doubts emerge regarding whether such RCTs are fair scientific tests of the experimental intervention. These doubts originate from the theoretical view that 'A plus B' will invariably amount to more than 'B' alone. Even in cases where treatment A is a pure placebo, its placebo and other nonspecific effects could lead to a better outcome in the experimental group than in the control group. This would be particularly likely if i) the experimental treatment is associated with sizable nonspecific effects, ii) a subjective outcome measure is used, and iii) the experimental intervention 'A' causes a deterioration of the condition being treated. http://www.jpgmonline.com/article.asp?issn=0022-3859;year=2008;volume=54;issue=3;spage=214;epage=216;aulast=Ernst Effectiveness of acupuncture for the prevention of episodic migraine. Cochrane. NNTB of 4. http://www.ncbi.nlm.nih.gov/pubmed/27351677?dopt=Abstract -un saludo juan gérvas @JuanGrvas