Patient Expectations of Assigned Treatments Impact Strength of Randomised Control Trials

Roberto Truzoli; Phil Reed; Lisa A Osborne

doi:10.3389/fmed.2021.648403

Patient Expectations of Assigned Treatments Impact Strength of Randomised Control Trials

Front Med (Lausanne). 2021 Jun 17:8:648403. doi: 10.3389/fmed.2021.648403. eCollection 2021.

Authors

Roberto Truzoli¹, Phil Reed², Lisa A Osborne^{3

4}

Affiliations

¹ Department of Biomedical and Clinical Sciences "L. Sacco", University of Milan, Milan, Italy.
² Department of Psychology, Swansea University, Swansea, United Kingdom.
³ School of Psychology and Counselling, The Open University, Milton Keynes, United Kingdom.
⁴ Women's Health, Swansea Bay University Health Board, Swansea, United Kingdom.

Abstract

Patient engagement with treatments potentially poses problems for interpreting the results and meaning of Randomised Control Trials (RCTs). If patients are assigned to treatments that do, or do not, match their expectations, and this impacts their motivation to engage with that treatment, it will affect the distribution of outcomes. In turn, this will impact the obtained power and error rates of RCTs. Simple Monto Carlo simulations demonstrate that these patient variables affect sample variance, and sample kurtosis. These effects reduce the power of RCTs, and may lead to false negatives, even when the randomisation process works, and equally distributes those with positive and negative views about a treatment to a trial arm.

Keywords: Monte Carlo simulations; RCT; clinical outcome-effectiveness; false negatives; patient expectations; patient variables.