Order effects: a randomised study of three major cancer-specific quality of life instruments.
BACKGROUND
In methodological studies and outcomes research, questionnaires often comprise several health-related quality of life (HRQoL) measures. Previous psychological studies have suggested that changing the sequential order of measurement scales within a questionnaire could alter the pattern of responses. Yet, information on the presence or absence of order effects on the assessment of HRQoL in cancer patients is limited.


METHODS
An incomplete block design was used in this study of 1277 cancer patients. Each patient filled out a questionnaire package that contained two of the three major cancer-specific HRQoL instruments, namely the Functional Assessment of Cancer Therapy--General, the European Organization for the Research and Treatment of Cancer Core Quality of Life Questionnaire and the Functional Living Index--Cancer. Within a questionnaire package the sequential order of the instruments contained were randomised. Measurement properties of the instruments, including the number of missing values, mean HRQoL scores, known-groups validity and internal consistency were compared between samples of different presentation orders.


RESULTS
No effect of presentation order on the four properties aforementioned was found.


CONCLUSIONS
Presentation order is unlikely to alter the responses to these HRQoL instruments administered in cancer patients when any two of them are used together.
Cheung
Yin-Bun
YB
MRC Tropical Epidemiology Group, London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK. yinbun.cheung@lshtm.ac.uk
Lim
Celestine
C
Goh
Cynthia
C
Thumboo
Julian
J
Wee
Joseph
J
D000203:Activities of Daily Living; D000328:Adult; D000704:Analysis of Variance; D016009:Chi-Square Distribution; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000208:ethnology / Q000523:psychology* / Q000628:therapy; D018579:Patient Selection; D011788:Quality of Life / Q000523:psychology*; D018434:Sickness Impact Profile; D012846:Singapore; D011795:Surveys and Questionnaires