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Table 5 Results of linear regression analysis for Total WOMAC score

From: Variations in the pre-operative status of patients coming to primary hip replacement for osteoarthritis in European orthopaedic centres

  Univariate Multivariate
  Mean WOMAC score (95%CI) Mean WOMAC score (95%CI)
Age groups:   
   < 50 56.8 (53.8, 59.8) 58.4 (54.7, 62.1)
   50–69 58.2 (57.0, 59.4) 57.5 (56.0, 59.0)
   70+ (reference) 61.0 (59.5, 62.5) 61.0 (59.2, 62.8)
P for trend 0.002 0.18
P for nonlinear trend 0.51 0.04
Sex:   
   Male (reference) 56.1 (54.7, 57.4) 55.7 (54.1, 57.3)
   Female 61.5 (60.3, 62.7) 61.6 (60.1, 63.1)
Obesity:   
   Not obese (reference) 58.2 (57.1, 59.2) 57.5 (56.2, 58.8)
   Obese 62.9 (61.0, 64.8) 62.5 (60.2, 64.7)
   Morbidly Obese 69.6 (61.0, 78.1) 67.2 (57.6, 76.7)
P for trend < 0.001 0.028
P for nonlinear trend 0.68 0.81
Employment status:   
   Employed 55.9 (54.1, 57.7) 56.7 (54.6, 58.9)
   Retired (reference) 59.6 (58.4, 60.8) 58.8 (57.3, 60.2)
   Retired Early 65.9 (62.8, 69.0) 65.3 (61.5, 69.1)
   Other 59.8 (56.9, 62.8) 59.6 (55.9, 63.3)
Qualifications after leaving school:   
   Postgraduate degree (reference) 49.3 (44.9, 53.7) 48.9 (43.3, 54.6)
   University degree 54.0 (51.4, 56.6) 53.8 (50.8, 56.7)
   College diploma, or equivalent 56.4 (54.8, 58.1) 56.9 (54.9, 58.9)
   None 62.1 (60.8, 63.4) 62.2 (60.7, 63.8)
P for trend < 0.001 < 0.001
P for nonlinear trend 0.31 0.96
ASA status:   
   1 55.5 (53.3, 57.7) 53.2 (50.5, 55.9)
   2 (reference) 58.7 (57.5, 59.9) 58.4 (57.0, 59.8)
   3 65.6 (63.4, 67.7) 64.6 (62.2, 67.1)
   4 59.3 (48.3, 70.3) 54.7 (40.3, 69.0)
P for trend < 0.001 < 0.001
P for nonlinear trend 0.042 0.06
Kellgren & Lawrence Grade:   
   0 60.1 (47.4, 72.8) 53.6 (37.0, 70.1)
   1 70.7 (56.7, 84.6) 77.1 (60.6, 93.7)
   2 55.7 (50.2, 61.2) 55.4 (49.4, 61.4)
   3 58.0 (56.5, 59.4) 58.4 (56.8, 60.0)
   4 (reference) 59.9 (58.5, 61.4) 59.4 (57.8, 61.0)
P for trend 0.16 0.66
P for nonlinear trend 0.12 0.14
  1. The square of the correlation coefficient (R-squared) in the multivariate model is 0.164, so the variables included in the regression model account for 16.4% of the variation in the total WOMAC score