Table 3

 Predictive factors of response to treatment: results of the logistic regression in the two study groups*

Paracetamol (n = 396)Placebo (n = 365)
ParameterOdds ratio95% CI†p Values‡Odds ratio95% CI†p Values‡
*Response to treatment was defined as a decrease of at least 30% in pain intensity during the 6 weeks of the study (ITT analysis). Patients included in these analyses are all the patients of the ITT population for whom complete data for the independent variables were available; †95% CI, 95% confidence interval; ‡Wald’s test; §MTF, medial tibiofemoral compartment; ¶NR, not relevant.
Sudden increase of pain within the 2 weeks before inclusion1.611.04 to 2.490.03381.651.05 to 2.580.0297
Morning stiffness (>20 minutes)1.641.05 to 2.540.0294NR
Pain at nightNR¶1.591.03 to 2.450.0370
Kellgren and Lawrence radiological score for MTF§0.780.65 to 0.940.0081NR
Body mass index (unit = 10 kg/cm2)1.681.10 to 2.560.0157NR
WOMAC function subscale (unit = 10 points)0.880.76 to 1.020.0965NR
Patient’s global assessment of knee OA (unit  =  10 mm)NR0.880.78 to 0.990.0385
Aetiology (primary or secondary OA)NR0.510.22 to 1.150.1022