Patient expectations in placebo-controlled randomized clinical trials

J Eval Clin Pract. 2005 Feb;11(1):77-84. doi: 10.1111/j.1365-2753.2004.00512.x.


Objective: To explore participants' experience in placebo-controlled randomized clinical trials (RCTs) specifically in relationship to their expectations.

Background: Aspects of being in RCTs, such as informed consent, perception of benefit and understanding of randomization, have been examined. In contrast, little is known concerning the formation of patient expectations before and during trials.

Methods: Qualitative methods using in-depth interviews with a semi-structured interview guide of nine patients from four different RCTs. Data analysis was conducted using a codebook format arranging participant responses under broad analytical headings. The interviewer used a semi-structured interview guide to direct the conversation from one broad topic to the next within the context of the ongoing conversation. A checklist of topics encouraged participants to describe their experiences in RCTs. Narratives concerning expectation, blinding and placebo were compared to identify common themes.

Results: Patient anticipatory processes were influenced and modified both before and during the trial from multiple inputs. Such factors as past experiences in RCTs, past experiences of ineffective treatment, stress of being off regular medications, fear of being a 'placebo responder', input of non-study doctors or other health professionals, the experience of other participants, measurements of health parameters made during the trial and the presence or absence of side-effects all affected patient expectation.

Conclusion: Expectations in RCTs are not fixed and instead may be viewed as continuously shaped by multiple inputs that include experience and information received both before and during the trial. Variability in placebo response observed in previous studies may be related to the fluid nature of expectations. Trying to control and equalize expectations in RCTs may be more difficult than previously assumed.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Aged
  • Female
  • Hospitals, Teaching
  • Hospitals, Urban
  • Humans
  • Interviews as Topic
  • Male
  • Middle Aged
  • Patient Participation / psychology*
  • Perception
  • Pilot Projects
  • Randomized Controlled Trials as Topic / psychology*
  • Research Subjects / psychology*