Psychometric properties of the Treatment Decision Evaluation Scale in patients with cancer in Turkey.

This paper is a report of a study to adapt the treatment decision evaluation scale for Turkish patients with cancer and to evaluate its psychometric properties. In 2006 a convenience sample of 199 patients with cancer at a Turkish university hospital completed a structured questionnaire including demographic characteristics and the treatment decision evaluation scale for patients with cancer. Item analysis, principal component analysis, internal consistency reliability, Cronbach's alpha, paired t-test and correlations were used to measure the psychometric properties of the items of the scale. In the assessment of construct validity, there were identified three factors with eigenvalues greater than 1 explained 43.3% of the total variance (Satisfaction-Uncertainty, Informed Choice and Decision Control). Factor analysis yielded that all of factor loadings were above 0.40 and factor loadings of the items ranged from 0.42 to 0.69 in the scales. Internal reliability coefficients of these three factors were found to be good, 0.74, 0.75 and 0.71, respectively. The present study provides evidence of the treatment decision evaluation scale's validity, reliability and acceptability in Turkish cancer patients. This scale should be further evaluated in different regions in Turkey and diverse populations. The scale has potential applications as it can be used both as a research or a regular treatment decision evaluation tool with clinical settings.