ABSTRACT
BACKGROUND: Patients' expectations, as a central mechanism behind placebo and nocebo effects, are an important predictor of health outcomes. Yet, theoretically based generic assessment tools allowing for an integrated understanding of expectations across conditions and treatments are lacking. Based on the preliminary 35-item version, this study reports the development and validation of the Treatment Expectation Questionnaire (TEX-Q), a generic, multidimensional self-report scale measuring patients' expectations of medical and psychological treatments. METHODS: The TEX-Q was developed in a validation sample of n = 251 patients undergoing different treatments using exploratory factor analyses and item analyses, as well as analysis of convergent and divergent validity. Confirmatory factor analysis was conducted in an independent sample of n = 303 patients undergoing cancer treatment. Two-weeks test-retest reliability was assessed in n = 28 psychosomatic outpatients. RESULTS: Factor analyses revealed six theoretically founded stable subscales. The TEX-Q assesses expectations of treatment benefit, positive impact, adverse events, negative impact, process and behavioural control with a total of 15 items. Results for the subscales and the sum score indicated good internal consistency (α = .71-.92), moderate to high test-retest reliability (r = .39-.76) as well as good convergent validity with regard to other expectation measures (r = .42-.58) and divergent validity with regard to measures of generalized expectations (r < .32) and psychopathology (r < .28). CONCLUSIONS: While further validation is needed, the results suggest that the TEX-Q is a valid and reliable scale for the generic, multidimensional assessment of patients' treatment expectations. The TEX-Q overcomes constraints of ad-hoc and disease-specific scales, while allowing to compare the impact of different expectation constructs across conditions and treatments.
Subject(s)
Motivation , Humans , Reproducibility of Results , Psychometrics , Surveys and Questionnaires , Self ReportABSTRACT
OBJECTIVE: Patients' expectations-as a central mechanism of placebo and nocebo effects-are an important predictor of health outcomes. However, the lack of a way to assess expectations across different settings restricts progress in understanding the role of expectations and to quantify their importance in medical and psychological treatments. The aim of this study was to develop a theory-based, generic, multidimensional measure assessing patient expectations of medical and psychological treatments. DESIGN: The Treatment Expectation Questionnaire (TEX-Q) was developed based on the integrative model of expectations and a systematic literature review of treatment expectation scales. After creating a comprehensive item pool, the scale was further refined by use of expert ratings and patient interviews. SETTING: Patients were recruited in primary care at two hospitals in Hamburg, Germany. PARTICIPANTS: 13 scientific experts participated in the expert survey. 11 patients waiting for psychological or surgical treatments participated in the qualitative interviews. RESULTS: The 2×2×2 multidimensional structure of the TEX-Q assesses two expectation constructs (probabilistic vs value-based) across two outcome domains with two valences (direct benefits and adverse events, broader positive and negative impact), plus process and behavioural control expectations. We examined 583 items from 38 scales identified in the systematic review and developed 78 initial items. Content validity was then rated by experts according to item fit and comprehensibility. The best 53 items were further evaluated for comprehensibility, acceptability, phrasing preference and understanding by interviewing patients prior to treatment using the 'think aloud' technique. This resulted in a first 35-item version of the TEX-Q. CONCLUSIONS: The TEX-Q is a generic, multidimensional measure to assess patient expectations of medical and psychological treatments and allows comparison of the impact of multidimensional expectations across different conditions. The final TEX-Q will be available after psychometric validation.
