Measuring individual quality of life in patients receiving radiation therapy: the SEIQoL-Questionnaire.

Purpose: Quality of life (QoL) is one of the most important outcomes in cancer care. Although a number of instruments to measure health-related QoL (HRQoL) exist, there are few suitable instruments to measure individual QoL. The best established instrument is the Schedule for the Evaluation of Individual Quality of Life (SEIQoL). The disadvantage of this questionnaire is its use of semi-structured interviews, which are very time-consuming. The purpose of our study was to transform the SEIQoL into an economical instrument that can be used in clinical trials with large samples.

Methods: We developed the SEIQoL-Questionnaire (SEIQoL-Q) on the basis of the SEIQoL-Direct Weighting (SEIQoL-DW) by transforming the interview guide into a written questionnaire. Patients (N = 1,108) in all three phases of radiation treatment (first consultation, ongoing irradiation, and aftercare) were asked to complete the SEIQoL-Q and the European Organization for Research and Treatment of Cancer QLQ-C30.

Results: While the average HRQoL measured by the QLQ-C30 was 55.6, the average SEIQoL-Q index was 59.6. The most important life domain was "physical health," followed by "emotional well-being" and "family." Patients attributed the highest level of satisfaction to "home/housing," followed by "family" and "partnership." Male patients were shown to have a significantly better QoL than females. The SEIQoL-Q index correlates moderately with the QLQ-C30 functioning scale "global quality of life" [r = .42 (p < .001)].

Conclusions: According to our findings, the SEIQoL-Q appears to be a feasible and economical instrument for use in quantitative research among cancer patients in different stages of their disease.