ArticlesInfluence of context effects on health outcomes: a systematic review
Introduction
As long ago as 400 BC, Hippocrates wrote of how “the patient, though conscious that his condition is perilous, may recover his health simply through his contentment with the goodness of the physician”.1 Balint added that what mattered was “not only the medicine…or the pills…but the way the doctor gave them to the patient—in fact the whole atmosphere in which the drug was given”.2 Although many have suggested that good doctor-patient relationships can have a therapeutic effect irrespective of any specific treatments provided by the practitioner, the extent to which this assumption is based on rigorous empirical evidence is not known. This lack of evidence is possibly a result of the focus of clinical research on the assessment of surgical and pharmacological interventions, and little emphasis on the effects of human care or “bedside manner” on health outcomes.
Nowadays, the influence of patients' expectations and the power of suggestion tend to be controlled for rather than investigated, and when noted, these effects are discounted as “non-specific” or “placebo” effects.3 However, given the proportion of patients who get better after receiving placebos,4 such effects are potentially of great value, and investigation of their healing properties is a worthwhile undertaking. In 1994, a series of articles5, 6, 7 and a review8 in The Lancet highlighted various aspects of the placebo effect, outlining how non-specific or “context” factors such as the method of treatment delivery interact with specific therapies (figure 1).
A systematic review by Turner and colleagues on pain and the placebo effect concluded that “The quality of the interaction between physician and patient can be extremely influential in patient outcomes, and…patient and provider expectations may be more important than specific treatment”.4 Effects originating from health-care interactions include factors common to all medical, alternative, and psychological therapies—eg, attention, bedside manner, empathy, positive regard, compassion, hope, and enthusiasm.9 Although a great deal of research has assessed the effects of training in studies do little to highlight the mechanisms by which health professionals can influence patients' health. Interventions tend to be complex, and researchers have little control over what occurs during consultations. Establishment of any cause-effect relation between components of the intervention and changes in the physiological state of the patient is therefore difficult. To understand how health practitioners can influence disease processes it is important to examine pathways and possible mechanisms by focusing on context interventions.
A useful framework to understand how these factors may influence healing is Leventhal's self-regulatory theory.11 This model suggests that when threatened by signs and symptoms of illness, individuals respond with cognitive and emotional reactions. For example, sudden pain may cause an individual to feel anxious and to try to make sense of the situation by thinking about what it might be, what caused it, whether it is curable, what the consequences could be, and how long these symptoms might last. In consultations, health professionals can be instrumental in shaping the way patients think and feel about their illness or their treatment, through the information and reassurance they provide. Alongside the use of appropriate diagnostic tests and treatment such as medication and surgery (physical care) and advice to practise a healthier lifestyle (behavioural care), practitioners can thus practise cognitive and emotional care as well (figure 2).
Cognitive care describes the ways by which practitioners can influence patients' beliefs about the effects of treatment or about the illness—eg, by giving a label to the condition or by giving a positive prognosis. Patients' expectations about a treatment can be made positive if they are told to expect the therapy to be “good”, “safe”, and “effective"; or negatively, if they are informed that the therapy they are about to receive is “dangerous”, “unsafe”, “ineffective”, “limited”, or has “potential side-effects”. Expectations can also be kept neutral, by withholding information or by giving unrelated information about the effects of a specific therapy. The term “emotional care” is used to refer to ways through which health professionals can lower unhelpful emotions such as fear or anxiety by providing support, empathy, reassurance, and warmth. Emotional and cognitive care are expected to work in an interactive manner, and to enhance substantially the effectiveness of therapy or physical care.
Some reviewers argue that the therapeutic influence of expectations and health-care interactions is real and powerful,12 whereas others feel that this effect is simply the result of methodological bias.13 Such debates are understandable given the conceptual and operational difficulties associated with the term “placebo effect”.14 In this study, we use the neutral and broader term “context effects” to refer to placebo effects deriving from patient-practitioner relationships. Since the assessment of therapeutic efficacy is best done by summarising evidence from randomised controlled trials, we did a systematic review of all such trials of the effects of patient-practitioner relationships on patients' health outcomes.
Section snippets
Methods
We designed comprehensive search strategies for a large number of medical, psychological, and sociological electronic databases (MEDLINE, Cochrane Controlled Trials Register, Cinahl, PsycLIT, Amed, Sociofile, Social Science Citation Index, Science Citation Index, EMBASE, SIGLE, and Dissertation Abstracts). These strategies are available from the authors. For MEDLINE alone, 183 search terms were used. These terms were related to the characteristics of practitioners, the patient-practitioner
Data collection
The hit rate from electronic searches was 23 645, of which 624 were selected as potentially relevant to the review. 25 trials, with a total of 3611 patients, met our inclusion criteria.16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38
Only 12 of the 25 studies presented enough information for a potential meta-analysis. Interventions in the eight trials with dichotomous outcomes were very different: they examined the effects of positive consultations,16, 17
Discussion
In reviewing context effects, we identified 25 trials that fulfilled our inclusion criteria. About half of these studies found positive effects on patients' health status after manipulation of patient-practitioner relationships. Conflicting findings are likely to have been influenced by the level of heterogeneity in the type of intervention, clinical sample, health outcomes, the methodological quality, and timing of the studies.
A combination of emotional and cognitive care (positive
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