Historically, a pill with no active ingredients. The concept is sometimes extended to include more sophisticated sham 'interventions'. Therapy given to conscious patients has the potential for at least four effects:
- Placebo effect
- Nocebo effect
- Beneficial biomedical effect
- Adverse biomedical effect
An observation that giving a placebo can produce reported improvements in symptoms despite the absence of active ingredients. Partly explained by the fact that many symptoms, for instance pain, are strongly modulated by psychological aspects so that fear and anxiety tend to accentuate pain.
Components of the Placebo Effect
It has been demonstrated that some of the factors contributing to the placebo effect can be separately analysed. This actually has produced results consistent with what is known of much of the art of medicine. Thus in one study the placebo of sham acupuncture produced a 16% improvement in adequate pain relief while the addition of a designed warmth, attention, and confidence building patient-practitioner relationship produced a further 18% gain .
Size of placebo effect
The size of the placebo effect is related to the parameter evaluated. One early overview of 15 controlled trials suggested 35.2%. In one study of the same stable asthmatics, that compared subjective improvement on visual analogue score, the improvement was 50% with salbutamol inhaler, 45% with placebo inhaler, 46% with sham acupuncture and 21% with no-intervention control (apart from interaction with study researchers). This study also showed that the objective measure FEV1 improved in 20.1% on the salbutamol but by only 7.3% in the other interventions.
- ↑ de Craen AJ, Roos PJ, Leonard de Vries A, Kleijnen J. Effect of colour of drugs: systematic review of perceived effect of drugs and of their effectiveness. BMJ. 1996 Dec 21-28;313(7072):1624-6. (Direct link)
- ↑ Kaptchuk TJ, Stason WB, Davis RB, Legedza AR, Schnyer RN, Kerr CE, et al. Sham device v inert pill: randomised controlled trial of two placebo treatments. BMJ (Clinical research ed.) 2006;332:391-7. (Direct link – subscription may be required.)
- ↑ Kleijnen J, de Craen AJ, van Everdingen J, Krol L. Placebo effect in double-blind clinical trials: a review of interactions with medications. Lancet. 1994;344:1347-9.
- ↑ Kaptchuk TJ, Kelley JM, Conboy LA, Davis RB, Kerr CE, Jacobson EE, Kirsch I, Schyner RN, Nam BH, Nguyen LT, Park M, Rivers AL, McManus C, Kokkotou E, Drossman DA, Goldman P, Lembo AJ. Components of placebo effect: randomised controlled trial in patients with irritable bowel syndrome. BMJ (Clinical research ed.). 2008 Apr 3.(Epub ahead of print) (Link to article – subscription may be required.)
- ↑ Woolf J, McManus IC. Medical stereotypes and medical realities. British medical journal (Clinical research ed.). 1987 Jun 27; 294(6588):1660.
- ↑ Furnham AF. Medical students' beliefs about nine different specialties. British medical journal (Clinical research ed.). 1986 Dec 20-27; 293(6562):1607-10.
- ↑ Fennema K, Meyer DL, Owen N. Sex of physician: patients' preferences and stereotypes. The Journal of family practice. 1990 Apr; 30(4):441-6.
- ↑ BEECHER HK. The powerful placebo. Journal of the American Medical Association. 1955 Dec 24; 159(17):1602-6.
- ↑ Wechsler ME, Kelley JM, Boyd IO, Dutile S, Marigowda G, Kirsch I, Israel E, Kaptchuk TJ. Active albuterol or placebo, sham acupuncture, or no intervention in asthma. The New England journal of medicine. 2011 Jul 14; 365(2):119-26.(Link to article – subscription may be required.)