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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