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The Nocebo Effect: Patient Expectations and Medication Side Effects Kate Faasse, Keith J Petrie

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The Nocebo Effect: Patient Expectations and Medication Side Effects Kate Faasse, Keith J Petrie Downloaded from pmj.bmj.com on July 11, 2013 - Published by group.bmj.com PGMJ Online First, published on July 10, 2013 as 10.1136/postgradmedj-2012-131730 Review The nocebo effect: patient expectations and medication side effects Kate Faasse, Keith J Petrie Department of Psychological ABSTRACT illness.7 When patients are prescribed a new drug Medicine, Faculty of Medical Expectation of treatment side effects is consistently or change to a new drug, many common unrelated and Health Sciences, The linked with those symptoms being realised. Patient symptoms are available to be mistakenly attributed University of Auckland, 1 Auckland, New Zealand expectations, including those generated by the informed to the new treatment. A review of clinical drug consent process, can have a large influence on the side trials showed that about one in five placebo-treated Correspondence to effects that patients feel after starting a new medical participants spontaneously reported side effects,8 Professor Keith Petrie, treatment. Such symptoms may be the result of the and almost 1 in 10 placebo users withdrew from Department of Psychological 9 Medicine, Faculty of Medical nocebo effect, whereby the expectation of side effects treatment because of side effects. and Health Sciences, The leads to them being experienced. Side effects may also This misattribution of symptoms appears to be par- University of Auckland, Private be due to the misattribution of pre-existing or unrelated ticularly common for people who experience higher Bag 92019, Auckland 1142, symptoms to the new medication. Medical professionals’ levels of negative emotions, with those reporting New Zealand; [email protected] own negative beliefs about a treatment, especially higher levels of psychological distress also reporting generic drugs, may further enhance patients’ higher rates of physical symptoms. Patients receiving Received 9 January 2013 expectations of adverse effects. The news media may chemoprevention treatment and travel vaccinations Revised 10 May 2013 also influence expectations, particularly when media who experience more negative emotions report sig- Accepted 20 June 2013 attention is directed towards a health or medication nificantly more symptoms after treatment, and attri- scare. This field of research has ethical and clinical bute more of these symptoms to treatment side implications for both medical professionals and the news effects.10 11 Symptoms of an underlying illness may media with respect to the level and type of information also be mistaken for treatment side effects.12 about treatment side effects that is provided to patients Expectations also play an important role in or members of the public. symptom misattribution. Participants’ beliefs about the likelihood of experiencing side effects, as well as expectations about the specific side effects of the INTRODUCTION active treatment, can influence outcomes in the The simple act of informing patients about the pos- placebo group of clinical trials. Participants in clin- sible side effects of a medication can dramatically ical drug trials are typically provided with informa- increase the number of patients who will experi- tion about the drug under investigation, including ence them. For example, patients who were told the likely adverse effects associated with the active that they might experience sexual side effects after treatment ingredient. Investigations show that treatment with β blocker drugs or hair loss medica- the side effects reported by the placebo group are tion reported these symptoms between three and usually the same side effects as those that are four times more often than patients in a control experienced by participants who are receiving group who were not informed about these symp- the active treatment.913 toms (32% vs 8%; 44% vs 15%, respectively).12 The experience of symptoms following medical The informed consent process involving the expli- treatment can have clinical implications for cit mention of medication side effects has the patients’ adherence to a treatment, and thus the potential to increase patients’ experience of them.3 longer-term success of the medical regimen. While The increase in side effects reported following it is widely acknowledged that drugs may generate information about a medical treatment might be the adverse events, some reported side effects are not result of a nocebo-like process. The nocebo effect related to the physiological action of the medica- occurs when the expectation of side effects results in tion. Evidence indicates that the experience of these symptoms being experienced in response to an symptoms of both the underlying condition and inert medication or procedure.4 While the nocebo medication side effects significantly reduces patient effect occurs in response to an inert treatment, there adherence across a range of chronic condi- – is also a nocebo component in the response to active tions.14 16 Patients may increase their medication treatment. Similarly, negative treatment expectations use in order attempt to control illness symptoms, may reduce drug effectiveness. In a recent study of or may reduce their dose if side effects of the medi- the opioid analgesic remifentanil, expectations of a cation are experienced.17 Lack of treatment adher- positive treatment outcome doubled the analgesic ence may result in inadequate therapeutic effects, effect of the drug, while expectations of a negative prompting medical professionals to increase medi- outcome eliminated the analgesic effect.5 cation dosage or discontinue treatment.17 To cite: Faasse K, Petrie KJ. It is also possible that in some cases patients may This paper examines how expectations influence Postgrad Med J Published Online First: [please include misattribute pre-existing or unrelated symptoms to the reporting of side effects of medical treatment. Day Month Year] the effects of a drug. Healthy people commonly We also discuss the role of expectations in health doi:10.1136/postgradmedj- experience somatic symptoms,6 and these symp- scares, and the part played by the media in influen- 2012-131730 toms are typically not indicative of underlying cing health worries and symptom complaints. The FaasseCopyright K, et al. Postgrad Article Med Jauthor2013;0:1– 7.(or doi:10.1136/postgradmedj-2012-131730 their employer) 2013. Produced by BMJ Publishing Group Ltd under licence. 1 Downloaded from pmj.bmj.com on July 11, 2013 - Published by group.bmj.com Review paper ends by looking at how expectations influence patient opioid. Similarly, negative expectations can reverse the analgesic outcomes in clinical settings, with a particular focus on the effect of nitrous oxide in dental pain.34 issues involved in providing accurate information to patients Some of the earliest research evidence that expectations can without causing unnecessary harm. influence the experience and reporting of adverse medication effects came about through the accidental omission of a small HOW DO EXPECTATIONS INFLUENCE SYMPTOM amount of information on a consent form. In a multicentre REPORTING? aspirin trial the information on the consent form across study Expectation of drug side effects can focus attention on these sites differed slightly; some participants received consent forms symptoms, resulting in greater detection and reporting of that included information about possible gastrointestinal side expected side effects. Greater self-focus on internal sensations is effects of the treatment, while others received consent forms associated with increased levels of symptom reporting.18 19 not containing this information. As a result, six times more par- Increasing the level of attention directed towards physical symp- ticipants who received the ‘additional’ information withdrew toms by the use of external cues, instructions, or information from the study because of gastrointestinal side effects.35 – provision also increases reported symptoms.20 22 It is likely that Manipulating patients’ expectations can also influence other such cues act to influence expectations about symptoms, and medical treatment. Patients who were receiving a local anaes- result in the selective monitoring only of symptoms that are in thetic injection were given either a positive expectation: ‘we are line with these expectations.23 going to inject the local anaesthetic that will numb the area and Holding a particular expectation about an illness or treatment you will be comfortable during the procedure,’ or a negative outcome can increase the experience of physical symptoms by expectation: ‘you are going to feel a big sting and burn in your directing attention towards particular symptoms, and thus increas- back now, like a big bee sting; this is the worst part of the proced- ing symptom reporting. These expectations and beliefs appear to ure’ (Varelmann et al,36 p.868). Patients who received the nega- facilitate a search process which results in people selectively search- tive information reported significantly greater pain from the ing for, and attending to, information that is in line with their injection than those who received more reassuring information. beliefs, as well as discounting expectation-inconsistent informa- Patients’ expectations about the outcome of a medical treat- tion.24 Directing attention towards illness expectations and beliefs ment or test may be influenced indirectly by experience, includ- using priming increases attention towards illness-specific words,25 ing previous medical treatments.32 The experience of and subsequently increases
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