# Table 3 Multinomial regression function: 'any OA'

N 666
Missing 49
NONE ISO-PF COMB
n = 212 n = 170 n = 284
aOR (95% CI)*   aOR (95% CI)*
Age (per year) 0.96 (0.93, 0.99) 1 1.04 (1.01, 1.07)
Female gender 2.87 (1.79, 4.59) 1 1.56 (0.99, 2.47)
BMI (per kg/m2) 0.94 (0.89, 0.99) 1 1.04 (0.99, 1.09)
Whole leg pain 2.12 (1.10, 4.08) 1 0.74 (0.37, 1.50)
Difficulty descending stairs 0.45 (0.27, 0.73) 1 1.15 (0.74, 1.80)
Intercondylar gap > 0 cm 1.38 (0.75, 2.57) 1 2.34 (1.32, 4.14)
Knee effusion† 0.82 (0.49, 1.35) 1 2.42 (1.55, 3.77)
Fixed flexion deformity 0.20 (0.04, 0.93) 1 2.31 (1.13, 4.77)
Coarse crepitus‡ 0.64 (0.40, 1.02) 1 1.57 (1.03, 2.41)
Knee flexion ROM (per degree) 0.99 (0.96, 1.01) 1 0.96 (0.94, 0.98)
Nagelkerke's Pseudo R2 0.41
Pearson goodness-of-fit P = 0.45
Pre-test probability 0.32 0.26 0.43
Correctly classified on 'balance of probabilities' 136 (64%) 36 (21%) 220 (77%)
Correctly classified on 'confident diagnosis' (probability ≥0.8) 18 (8%) 0 79 (28%)
1. * odds ratio with 95% confidence interval, adjusted for all other covariates in model. aOR is interpreted as the odds relative to the ISO-PF group (for example, compared to those people with ISO-PF, people with COMB have 2.4 times the odds of having knee effusion; compared with ISO-PF, those with no ROA have 0.45 times the odds of difficulty descending stairs, that is, lower risk).
2. †Mild/Moderate/Gross
3. ‡Possible/definite