A therapy impact questionnaire for quality-of-life assessment in advanced cancer research.

The first part of the validation procedure used for a Therapy Impact Questionnaire (TIQ) on quality-of-life assessment in advanced cancer patients is described. The TIQ is composed of 36 items which assess both disease and therapy impact according to four dimensions that operationally define quality of life: physical symptoms (24 items), functional status (3 items), concomitant emotional and cognitive factors (6 items) and social interaction (2 items). A global judgement expressed as "have you been feeling ill" further completes the TIQ. Patients answered each question using a 4-point verbal Likert scale: not at all, slight, a lot and very much. The TIQ was given to 1,000 consecutive patients who were no longer responsive to cancer treatment and presented symptoms due to disease progression. The compliance rate was quite high (87%). Results of confirmatory factor analysis were consistent with the operational dimensions identified during questionnaire construction. In particular, the dichotomized answers to 3 functional status items could be used as a Guttman scale. In a sub-sample of 50 patients, the reproducibility of functional status items was assessed using a 7-item parallel form. The intraclass correlation coefficient obtained indicated a reasonably high reproducibility. On the basis of the analyses conducted, the TIQ appears to be a reliable and concise instrument for studies aimed to assess the effectiveness of therapies in advanced cancer patients.