Order effects in the assessment of quality of life in cancer patients

Abstract

Methodological studies and outcome research often include several health-related quality of life (HRQoL) measurement scales in one questionnaire. Psychological studies have previously demonstrated that changing the sequential order of measurement scales within a questionnaire can alter the pattern of responses. Little is known, however, about whether there are order effects on the assessment of HRQoL in cancer patients. Here we address this issue in a study of 190 Singaporean cancer patients who were assessed using two different HRQoL instruments placed in alternating sequence within a questionnaire package. Measurement properties of the instruments, including the number of missing values, means, variability, known-group validity and internal consistency, were compared in the two samples representing different presentation orders. The HRQoL instruments administered in different sequential orders appeared to be equivalent in several aspects. No major effect of presentation order on outcomes was shown. The reasons and implications of the absence of an order effect are discussed. We conclude that presentation order is unlikely to alter the responses to the two HRQoL instruments.

Validation of the English and Chinese versions of the Quick-FLIC quality of life questionnaire

“…However, recent studies suggested that the context of HRQoL assessment has little effect on HRQoL scores (Kemmler et al, 1999;Cheung et al, 2004b). Furthermore, a comparison of the findings of the Chinese Quick-FLIC in this study with our previous study, where the 11 items Quick-FLIC was administered as an independent instrument showed similar results.…”

“…One challenge may be that the validity and reliability of these 11 items administered as part of the FLIC could have been affected by the other FLIC items. However, recent studies suggested little context effect in quality of life assessment (Kemmler et al, 1999;Cheung et al, 2004b). Furthermore, we also used the same 11 items in Chinese to re-evaluate the Chinese version of Quick-FLIC.…”

Validity and Responsiveness of Generic Preference-based HRQOL Instruments in Chronic Epilepsy

“…Order was not specified, so it is unlikely that instruments were administered in the same order across study sites and time periods. Order effects are found more often in large population-based surveys of predominantly healthy individuals than in surveys of smaller samples of the chronically ill [74][75][76]. This may reflect limited power to detect small effects.…”

Mapping the eight-item Parkinson’s Disease Questionnaire (PDQ-8) to the EQ-5D utility index

“…One of the two surveys used PDQ-8 alone, whereas the other administered the eight items embedded in the PQD-39. However, various studies have shown that there is little context effect in the qualityof-life assessment [27,28], so we believed that the data from the two surveys can be pooled. We also used the present data to explore the possibility of a context effect.…”