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BLISS index for analyzing knee osteoarthritis trials data
Nicholas Bellamy1, Mary J Bell, Dan Pericak
1Centre of National Research on Disability and Rehabilitation Medicine (CONROD), The University of Queensland, Queensland, Australia, 4006. n.bellamy@uq.edu.au
Journal of Clinical Epidemiology
|January 9, 2007
Summary
The BLISS Index effectively differentiates knee osteoarthritis treatment groups using the WOMAC Pain Scale at low pain levels. This new method helps identify patients achieving a good health state post-treatment.
Area of Science:
- Rheumatology
- Clinical Trial Methodology
Background:
- Knee osteoarthritis (OA) management requires sensitive outcome measures.
- Differentiating treatment efficacy at low symptom levels is challenging.
Purpose of the Study:
- To evaluate the BLISS (Bellamy et al. Low Intensity Symptom State-attainment) Index for analyzing knee OA clinical trial data.
- To determine if the WOMAC Pain Scale (WOMAC-P) at various thresholds can differentiate treatment groups (hylan G-F 20 vs. appropriate care) at low and very low pain states.
Main Methods:
- Five analyses using the BLISS Index were performed: time to first BLISS day, BLISS days over 12 months, BLISS response at month 12, BLISS response at any time, and number of BLISS periods.
- The WOMAC Pain Scale (WOMAC-P) thresholds examined were <=5, <=10, <=15, <=20, and <=25 normalized units (NU).
Main Results:
- The hylan G-F 20 group showed greater achievement of BLISS states across all five analyses.
- Statistically significant differences between treatment groups were observed for all WOMAC-P pain thresholds except <=5 NU.
Conclusions:
- The proposed BLISS Index methods, using prespecified pain thresholds, successfully discriminated between treatment groups.
- BLISS-10 represents a therapeutically attainable low symptom state, offering a benchmark for assessing interventions in knee OA.
- Further research is needed to elaborate on the patient-reported value of achieving low and very low pain intensity states.