Table 2

Univariate and multivariate association models to assess the relationship between risk factors and incident KOA in RS-I

UnivariateMultivariate 1Multivariate 2Multivariate 3
Risk factorOR95% CIp ValueOR95% CIp ValueOR95% CIp ValueOR95% CIp Value
Gender (% F)2.131.72 to 2.644.3×10−121.901.47 to 2.446.8×10−71.851.42 to 2.404.7×10−61.661.25 to 2.193.9×10−4
Age (years)0.990.89 to 1.100.840.990.89 to 1.100.850.990.89 to 1.100.830.890.79 to 1.000.06
BMI (kg/m2)1.411.28 to 1.555.0×10−121.361.23 to 1.508.8×10−101.361.23 to 1.509.6×10−101.281.15 to 1.427.3×10−6
Knee pain*1.811.42 to 2.322.4×10−61.651.27 to 2.141.7×10−41.641.26 to 2.132.0×10−41.621.22 to 2.160.001
Disability index*1.080.98 to 1.190.110.970.87 to 1.080.610.970.88 to 1.090.640.950.84 to 1.070.41
General health*0.950.63 to 1.420.790.860.55 to 1.340.500.860.55 to 1.330.490.990.62 to 1.580.96
Smoking*0.660.53 to 0.817.8×10−50.920.73 to 1.170.510.920.73 to 1.170.490.980.76 to 1.260.85
Educational level*0.950.90 to 1.000.071.010.95 to 1.080.691.010.95 to 1.080.691.010.95 to 1.080.71
Heavy work*0.750.55 to 1.030.080.860.62 to 1.190.350.860.62 to 1.190.350.870.61 to 1.240.44
Genetic score1.171.06 to 1.290.0021.040.94 to 1.160.441.120.99 to 1.250.07
Hand OA†1.821.47 to 2.254.7×10−81.441.13 to 1.840.003
Hip OA†1.080.75 to 1.530.691.010.68 to 1.520.95
Baseline knee KL score 1†7.295.77 to 9.213.1×10−626.975.48 to 8.871.8×10−56
  • Standardised scores ((x-mean)/SD) were made for continuous variables, such that the OR in the multivariate models was expressed as percentage of increased or decreased risk per SD.

  • For continuous variables, the OR per increase in SD is shown (age, BMI, disability index and genetic score).

  • *‘Questionnaire’ variables.

  • †X-ray variables.

  • BMI, body mass index; KL, Kellgren & Lawrence; KOA, knee osteoarthritis; OA, osteoarthritis; RS-I, Rotterdam Study I.