BLISS index using WOMAC index detects between-group differences at low-intensity symptom states in osteoarthritis

Bellamy, Nicholas; Bell, Mary J.; Goldsmith, Charlie H.; Lee, Shelley; Maschio, Michael; Raynauld, Jean-Pierre; Torrance, George W.; Tugwell, Peter

doi:10.1016/j.jclinepi.2009.07.011

« Previous Next »Journal of Clinical Epidemiology
Volume 63, Issue 5 , Pages 566-574, May 2010

BLISS index using WOMAC index detects between-group differences at low-intensity symptom states in osteoarthritis

Nicholas Bellamy
- Centre of National Research on Disability and Rehabilitation Medicine (CONROD), The University of Queensland, Level 3, Mayne Medical School, Herston Road, Brisbane, QLD 4006, Australia
- Corresponding author. Tel.: +011-61-7-3365-5558; fax: +011-61-7-3346-4603.
Mary J. Bell
- Rheumatology and Clinical Epidemiology, Sunnybrook & Women's College Health Sciences Centre, University of Toronto, Toronto, Ontario, Canada
Charlie H. Goldsmith
- Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, Ontario, Canada
Shelley Lee
- i3 Innovus, Burlington, Ontario, Canada
Michael Maschio
- i3 Innovus, Burlington, Ontario, Canada
Jean-Pierre Raynauld
- Department of Medicine, University of Montreal, Montreal Institute of Rheumatology, Montreal, PQ, Canada
George W. Torrance
- Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, Ontario, Canada
- i3 Innovus, Burlington, Ontario, Canada
Peter Tugwell
- Department of Medicine, Faculty of Medicine, Ottawa Hospital, General Campus, Ottawa, Ontario, Canada
- Centre for Global Health, Institute of Population Health, University of Ottawa, Ottawa, Ontario, Canada

Accepted 4 August 2009. published online 09 November 2009.

Abstract

Objectives

The ability of the Bellamy et al. Low-Intensity Symptom State-attainment (BLISS) Index to differentiate between treatment groups (hylan G-F 20 vs. appropriate care) at low and very low levels of state attainment in patients with knee osteoarthritis was explored using the stiffness, function, and total index (TI) components of the WOMAC.

Study Design and Setting

Six different BLISS measures were analyzed using five WOMAC score thresholds: ≤5 normalized units (NUs): ≤10, ≤15, ≤20, and ≤25 (lower=better health).

Results

More patients in the hylan G-F 20 group achieved BLISS states in all three WOMAC subscales for all six BLISS analyses. These differences were statistically significant for the BLISS response at any time at all threshold levels except ≤5NU.

Conclusions

The six BLISS measures and threshold levels of stiffness, function, and TI score were able to statistically discriminate between treatment groups. BLISS-10 is a therapeutically attainable very low symptom state at which clinically important statistically significant between-group differences are detectable in pain, stiffness, function, and TI score and therefore may provide a benchmark against which therapeutic interventions can be assessed. However, the value to patients of these symptom states requires further elaboration.

Keywords: Effectiveness, Hylan G-F 20, Osteoarthritis, Randomized controlled trial, State attainment, WOMAC index