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

Objectives: The ability of the Bellamy et\ua0al. 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 ≤5 NU. 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