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From *the Institute for Work and Health, Toronto, Ont., the Departments of
Public Health Sciences and of
Family and Community Medicine, University of Toronto, Toronto, Ont., and
the Population Health Program, Canadian Institute for Advanced Research, Toronto, Ont.
Correspondence to: Dr. Donald C. Cole, Institute for Work and Health, 702250 Bloor St. E, Toronto ON M4W 1E6; dcole{at}iwh.on.ca
| Abstract |
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Methods: We searched MEDLINE for English-language articles published from 1966 to June 1998 with a title or abstract containing at least 1 of the medical subject headings (MeSH) "self-assessment," "self-concept" or "attitude to health," or the MeSH subheading "psychology," and at least 1 word from each of 3 sets: "patient" and similar words; a form of "expectation," "belief" or "prediction"; and a form of "recover," "outcome," "survival" or "improve." Relevant articles contained original research data, measured patients' recovery expectations, independently measured a subsequent health outcome and analyzed the relation between expectations and outcomes. We assessed internal validity using quality criteria for prognostic studies based on 6 categories (case definition; patient selection; extent of follow-up; objective outcome criteria; measurement and reporting of recovery expectations; and analysis).
Results: A total of 1243 titles or abstracts were identified through the computer search, and 93 full-text articles were retrieved. Forty-one of these articles met the relevance criteria, along with 4 additional articles identified through other means. Agreement beyond chance on quality assessments of 18 randomly selected articles was high (kappa = 0.87, p = 0.001). Sixteen of the 45 articles provided moderate-quality evidence and included a range of clinical conditions and study designs; 15 of the 16 showed that positive expectations were associated with better health outcomes. The strength of the relation depended on the clinical conditions and the measures used.
Interpretation: Consistency across the studies reviewed and the evidence they provided support the need for clinicians to clarify patients' expectations and to assist them in having appropriate expectations of recovery. The understanding of the nature, extent and clinical implications of the relation between expectations and outcomes could be enhanced by more conceptually driven and methodologically sound research, including evaluations of intervention effectiveness.
Yet despite useful narrative reviews on expectancy of therapeutic gain5 >and the mechanisms by which expectancy can affect outcomes,6 we were unable to locate a systematic review of the predictive relation between patients' recovery expectations and subsequent health outcomes. In this article we report on such a review we conducted using accepted procedures for locating, selecting and evaluating the quality of evidence.7 We summarize qualitatively the results of studies in the medical literature that provide at least moderate-quality evidence, comment on approaches to utilization of existing evidence and suggest fruitful research avenues.
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A quality assessment modelled after approaches described elsewhere8,9 was used to assess the internal validity of the identified studies (Table 1). To be considered as providing moderate-quality evidence, the studies had to have a follow-up of 80% of the total sample, have outcome criteria appropriate to the research question, clearly describe the instrument used to measure recovery expectations, and have a stratified analysis, adjustment for a single confounder or presentation of data in a manner that would allow analysis of subsets. One of us (M.V.M.) assessed the validity of each of the selected articles. Another (D.C.C.), who was blind to the assessment of the first author, independently evaluated 18 randomly selected articles for quality of evidence. Agreement beyond chance between assessors on a dichotomous classification of moderate versus weak quality was calculated using Cohen's kappa statistic.10 The second reviewer subsequently assessed the validity of all the articles deemed by the first author as having provided moderate-quality evidence. Disagreements in assessments of quality of evidence at this stage were resolved by consensus.
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Substantial differences in conditions, questions, outcomes and analytic strategies prevented more formal quantitative summation of effect sizes. Qualitative interpretation of effect sizes was done in keeping with Cohen's approach.11 Synthesis thus relied on the qualitative approach of reflecting on commonalities and differences, and on linking with conceptual work and research findings.12
| Results |
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Table 3 describes the questions, results and effect sizes for the different clinical conditions in the 16 studies that provided moderate-quality evidence. Fifteen of the studies were observational, and 1 was experimental.15 Myocardial infarction was the most commonly studied condition (in 3 of the studies);13,17,25 the next most commonly studied conditions were cardiac surgery,18,22 chronic pain14,26 and psychiatric conditions15,27 (each in 2 studies). Only 2 studies shared a common question regarding expectations (anticipation of postoperative pain on a scale ranging from "not at all" to "extremely").16,23 Studies tended to include a minimum of 1 variable covering at least 2 of the biologic and physiologic, psychological or social domains (e.g., peak creatinine kinase and mental health index in myocardial infarction patients,25 or Nottingham Health Profile and occupation in prostatectomy cases6).
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Simultaneous control for the effects of biologic and physiologic variables or of psychological or social variables6,13,15,16,17,19,22,25 usually had little effect on the strength of the relation between expectations and outcome, which indicated an independent influence of recovery expectations on health outcomes. Maximum effect sizes within a study for differences in recovery expectations, estimable for all but one of the studies, ranged from small (4 of 15 studies) through medium (5 studies) to large (6 studies). Little differentiation in effect size by type of condition was apparent, although smaller effect sizes tended to be more common for psychological conditions (e.g., social phobia), and larger effect sizes for medical conditions (e.g., obesity). Measures of the predictive utility of measurements of recovery expectations were minimal (only 1 study reported on the sensitivity and specificity of a question [68% and 71% respectively], which asked patients with chronic low-back pain to predict the outcome of a vocational rehabilitation program14). Estimates of relative risks of a given outcome for various levels of recovery expectations were absent. Emphasis was on statistical inference testing rather than on predictive utility.28,29
| Interpretation |
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Most authors suggested ways to apply their research; for example, patients who expect complications should be "targeted for psychological support and patient education prior to surgery,"16 and the assessment of illness perceptions may help to identify which patients "may benefit from another intervention before attending a rehabilitation programme."25 Uncertainty about the causal versus the predictive role of patients' recovery expectations, hesitation in deliberately manipulating expectations, and limited rigorous evaluation of interventions to modify expectations (in 1 of the studies we reviewed) may limit such suggestions. Yet the consistency across studies and the supporting body of corroborative evidence argue for more confidence in the research findings. While avoiding the generation of false hopes and assisting patients with appropriate recovery expectations, physicians may improve adherence to treatment regimens and foster patient behaviours that "not only require positive motivation but also the knowledge and skills to pursue the desired goals."17
Considerable scope exists for improving the validity and utility of research into the effect of recovery expectations on health outcomes. Ways to achieve this could include working toward a core set of reliable and valid measures of recovery expectations, bearing in mind that "the best prediction of outcome would be an expectancy-measure whose domain of behaviour matches that of the outcome";17 including such measures in prognostic models37,38,39,40 while articulating better the effect size associated with such measures for clinical audiences;8,41,42 and incorporating such measures into trials that treat recovery expectations as an intermediate variable, measured at baseline and modified through interventions. Such research should improve treatment recommendations for effective methods of fostering more positive recovery expectations and of ultimately improving patient health outcomes.
| Acknowledgments |
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This project was sponsored by the Institute for Work and Health. The institute, an independent, not-for-profit research organization, receives support from the Ontario Workplace Safety and Insurance Board.
| Footnotes |
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Contributors: Drs. Mondloch and Cole were responsible for the concept and design of the study, the analysis and interpretation of the data, and the writing and revising of the manuscript; Dr. Mondloch was also responsible for data collection. Dr. Frank was responsible for the design of the study, the analysis and interpretation of the data, and the revising of the manuscript.
Competing interests: None declared.
| References |
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