16. Clinical Interpretation

  1. Peter M. Fayers1,2 and
  2. David Machin3,4

Published Online: 8 MAR 2002

DOI: 10.1002/0470846283.ch16

Quality of Life: Assessment, Analysis and Interpretation

Quality of Life: Assessment, Analysis and Interpretation

How to Cite

Fayers, P. M. and Machin, D. (2000) Clinical Interpretation, in Quality of Life: Assessment, Analysis and Interpretation, John Wiley & Sons, Ltd, Chichester, UK. doi: 10.1002/0470846283.ch16

Author Information

  1. 1

    Medical Research Council Clinical Trials Unit, London, UK

  2. 2

    Unit of Applied Clinical Research, Norwegian University of Science and Technology, Trondheim, Norway

  3. 3

    NMRC Clinical Trials & Epidemiology Research Unit, Singapore

  4. 4

    School of Health and Related Research, University of Sheffield, UK

Publication History

  1. Published Online: 8 MAR 2002
  2. Published Print: 18 APR 2000

ISBN Information

Print ISBN: 9780471968610

Online ISBN: 9780470846285



  • statistical significance;
  • absolute levels;
  • population norms;
  • threshold values;
  • effect size;
  • meta-analysis;
  • patient variables


Interpretation of QoL scores raises many issues. The scales and instruments used may be unfamiliar to many clinicians and patients, who may be uncertain of the meaning of the scale values and summary scores. Various methods aimed at providing familiarity of scale scores and understanding the meaning of changes in scores are described. As well as the use of population-based reference values from healthy individuals and from groups of patients with known health status and various illnesses, patient-orientated methods are discussed. These include identification of the minimal changes in QoL that are discernible by patients, or are important to patients; the impact of QoL states upon behaviour; and the changes in QoL that are caused by major life events. Data-derived “effect sizes”, which consider the random variability of the observed data, provide yet another method and can be particularly useful when reference values and patient-orientated information are not available.