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A comparison of the FACT-G and the Supportive Care Needs Survey (SCNS) in women with ovarian cancer: unidimensionality of constructs

Abstract

Purpose  

Health-related quality of life (HRQoL) and unmet needs (needs) questionnaires offer alternative perspectives for assessing
cancer patients’ concerns. We examined whether the conceptual differences underlying these alternative approaches yield corresponding
empirical differences.

Methods  

Eight-hundred and seventy-four women with ovarian cancer completed the Functional Assessment of Cancer Therapy scale (FACT-G;
HRQoL) and the Supportive Care Needs Survey (SCNS-SF34; needs) every 3 months for 2 years. Correlational analysis, exploratory
and confirmatory factor analysis (EFA/CFA), and Rasch analysis tested the relationship between patients’ responses to similar
domains and similar items across the two questionnaires.

Results  

Strong correlations were found between items with virtually identical wording (0.67–0.75), while moderate to strong correlations
(0.55–0.65) were found for those with very similar wording. EFA identified two common domains across the two questionnaires:
physical and psychological. For each common domain, CFA indicated models involving a single construct with systematic variation
within each questionnaire fit best. Rasch analysis including very similar items within the physical and psychological domains
(separately) demonstrated strong evidence of unidimensionality.

Conclusions  

The high degree of similarity between patient responses to items addressing the same or very similar concerns suggests either
that HRQoL and needs approaches do not reflect different constructs or that patients may not be able to differentiate between
the severity of a concern and the level of need associated with that concern, especially when these are assessed in quick
succession.

  • Content Type Journal Article
  • Pages 1-11
  • DOI 10.1007/s11136-011-9993-5
  • Authors
    • B. Colagiuri, Psycho-oncology Co-operative Research Group, The University of Sydney, Sydney, NSW, Australia
    • M. T. King, Psycho-oncology Co-operative Research Group, The University of Sydney, Sydney, NSW, Australia
    • P. N. Butow, Psycho-oncology Co-operative Research Group, The University of Sydney, Sydney, NSW, Australia
    • J. A. McGrane, Pearson Psychometric Laboratory, Graduate School of Education, The University of Western Australia, Crawley, WA, Australia
    • T. Luckett, Psycho-oncology Co-operative Research Group, The University of Sydney, Sydney, NSW, Australia
    • M. A. Price, Psycho-oncology Co-operative Research Group, The University of Sydney, Sydney, NSW, Australia
    • D. P. Birney, School of Psychology, The University of Sydney, Sydney, NSW, Australia
    • The Australian Ovarian Cancer Study Group, Department of Gynaecological Oncology, Westmead Hospital and Westmead Institute for Cancer Research, University of Sydney at the Westmead Millennium Institute, Westmead, NSW, Australia
    • The Australian Ovarian Cancer Study—Quality of Life Study Investigators, School of Psychology, The University of Sydney, Sydney, NSW, Australia