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J R Soc Med. 1997 December; 90(12): 652–656.
PMCID: PMC1296732

Are randomized controlled trials controlled? Patient preferences and unblind trials.

Abstract

The most reliable information about treatment effects comes from randomized controlled trials (RCTs). However, the possibility of subtle interactions--for example, between treatment preferences and treatment effects--is generally subordinated in the quest for evidence about main treatment effects. If patient preferences can influence the effectiveness of treatments through poorly understood (psychological) pathways, then RCTs, particularly when unblinded, may wrongly attribute effects solely to a treatment's physiological/pharmacological properties. To interpret the RCT evidence base it is important to know whether any preference effects exist and, if so, by how much they affect outcome. Reliable measurement of these effects is difficult and will require new approaches to the conduct of trials. In view of the fanciful image with which such effects are portrayed and the uncertainties about their true nature and biological mechanisms, existing evidence is unlikely to provide sufficient justification for investment in trials. This is a Catch 22. Until an escape is found we might never know, even approximately, how much of modern medicine is attributable to psychological processes.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.
  • O'Boyle CA. Diseases with passion. Lancet. 1993 Nov 6;342(8880):1126–1127. [PubMed]
  • Rücker G. A two-stage trial design for testing treatment, self-selection and treatment preference effects. Stat Med. 1989 Apr;8(4):477–485. [PubMed]
  • Torgerson DJ, Klaber-Moffett J, Russell IT. Patient preferences in randomised trials: threat or opportunity? J Health Serv Res Policy. 1996 Oct;1(4):194–197. [PubMed]
  • Lilford RJ, Jackson J. Equipoise and the ethics of randomization. J R Soc Med. 1995 Oct;88(10):552–559. [PMC free article] [PubMed]
  • Nicolaides K, Brizot M de L, Patel F, Snijders R. Comparison of chorionic villus sampling and amniocentesis for fetal karyotyping at 10-13 weeks' gestation. Lancet. 1994 Aug 13;344(8920):435–439. [PubMed]
  • McPherson K. The Cochrane Lecture. The best and the enemy of the good: randomised controlled trials, uncertainty, and assessing the role of patient choice in medical decision making. J Epidemiol Community Health. 1994 Feb;48(1):6–15. [PMC free article] [PubMed]
  • Chaput de Saintonge DM, Herxheimer A. Harnessing placebo effects in health care. Lancet. 1994 Oct 8;344(8928):995–998. [PubMed]
  • 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 Nov 12;344(8933):1347–1349. [PubMed]
  • Phillips DP, Ruth TE, Wagner LM. Psychology and survival. Lancet. 1993 Nov 6;342(8880):1142–1145. [PubMed]
  • Levy SM, Herberman RB, Lee J, Whiteside T, Beadle M, Heiden L, Simons A. Persistently low natural killer cell activity, age, and environmental stress as predictors of infectious morbidity. Nat Immun Cell Growth Regul. 1991;10(6):289–307. [PubMed]
  • Redd WH, Silberfarb PM, Andersen BL, Andrykowski MA, Bovbjerg DH, Burish TG, Carpenter PJ, Cleeland C, Dolgin M, Levy SM, et al. Physiologic and psychobehavioral research in oncology. Cancer. 1991 Feb 1;67(3 Suppl):813–822. [PubMed]
  • Macintyre IM. Tribulations for clinical trials. BMJ. 1991 May 11;302(6785):1099–1100. [PMC free article] [PubMed]
  • Pandora and the problem of evil. Lancet. 1996 Jan 6;347(8993):1–1. [PubMed]
  • Rothman KJ. Placebo mania. BMJ. 1996 Jul 6;313(7048):3–4. [PMC free article] [PubMed]
  • Chalmers I. What is the prior probability of a proposed new treatment being superior to established treatments? BMJ. 1997 Jan 4;314(7073):74–75. [PMC free article] [PubMed]
  • Brewin CR, Bradley C. Patient preferences and randomised clinical trials. BMJ. 1989 Jul 29;299(6694):313–315. [PMC free article] [PubMed]

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