Journal Outcomes Research

Measurement of rapid changes in health outcomes in people with influenza symptoms

Richard H Osborne PhD1,2, Graeme Hawthorne PhD3, Margaret Papanicolaou BSc4 and Yann Wegmueller BSc, MBA5

1 Department of Epidemiology and Biostatistics, Erasmus University Medical Centre, Rotterdam, The Netherlands
2 Centre for Genetic Epidemiology, The University of Melbourne, Melbourne, Australia.
3 Centre for Health Program Evaluation, Department of General Practice and Public Health, The University of Melbourne, Melbourne, Australia
4 Synermedica Pty Ltd, Malvern, Australia
5 F. Hoffmann-La Roche Ltd, Basel, Switzerland

Keywords: health-related quality of life, influenza, psychometrics, questionnaire, acute disease, clinical trial

Summary
Clinical trials' outcomes assessment requires symptoms and health status tracking, particularly where symptoms come and go rapidly. We report indicators assessing health in people suffering influenza symptoms where changes occur daily.

Thirty-six people with influenza symptoms completed self-report questionnaires daily for 8 days: including the Influenza Impact Wellbeing Scale (IIWS) probing health, sleep quality and ability to perform usual activities; and the Assessment of Quality of Life (AQoL), a health-related quality of life instrument. An 11-item checklist, the Influenza Symptom Severity (ISS) scale, assessed influenza symptoms severity. Psychometric properties of the IIWS and ISS are reported.

Over the 8 days, ISS scores decreased by 75%, IIWS scores increased by 58% and AQoL scores improved by 10% (all p <0.01). Influenza symptoms recorded by the ISS scale predicted 50% of the variation in the IIWS.

All three instruments were sufficiently sensitive to track rapid health status changes and may be useful outcomes measures in clinical trials involving influenza patients. These are promising results that require confirmation in larger studies.