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Table 2 Cohort description by pain group

From: Identifying individuals with chronic pain after knee replacement: a population-cohort, cluster-analysis of Oxford knee scores in 128,145 patients from the English National Health Service

 

Low pain (OKS-PS > 14)

High pain (OKS-PS ≤ 14)

Observations: n (%)

107,542 (85.3%)

18,522 (14.7%)

Gender: n (%)

 Female

57,771 (54%)

10,343 (56%)

 Male

42,683 (40%)

6623 (36%)

 Not specified

98 (0%)

8 (0%)

Missing

6990 (7%)

1548 (8%)

Age band: n (%)

 40–49 years of age

167 (0%)

91 (0%)

 50–59 years of age

8668 (8%)

2712 (15%)

 60–69 years of age

37,112 (35%)

6471 (35%)

 70–79 years of age

42,070 (39%)

6003 (32%)

 80–89 years of age

12,529 (12%)

1697 (9%)

 90+ years of age

6 (0%)

0 (0%)

Missing

6990 (7%)

1548 (8%)

Pre-op OKS score1

 Mean (SD)

19.8 (8)

14.4 (8)

 Median (IQR)

20 (11)

14 (10)

Missing

1229 (1%)

244 (1%)

Standardised pre-op OKS-Pain score 2

 Mean (SD)

36.5 (16)

25.6 (15)

 Median (IQR)

35.7 (21.42)

25.0 (21.42)

Missing

1227 (1%)

243 (1%)

Standardised pre-op OKS-Function score 3

 Mean (SD)

48.0 (18)

36.4 (17)

 Median (IQR)

45 (25)

35 (20)

Missing

1185 (1%)

240 (1%)

Pre-op EQ-5D index4

 Mean (SD)

0.442 (0.30)

0.249 (0.32)

 Median (IQR)

0.620 (0.532)

0.159 (0.603)

Missing

5887 (5%)

1990 (11%)

Pre-op EQ-5D VAS5 “Your own health state today”

 Mean (SD)

69.6 (19)

59.8 (22)

 Median (IQR)

74 (25)

60 (35)

Missing

10,807 (10%)

2304 (12%)

“How would you describe the results of your operation?” n (%)

 Excellent

31,212 (29%)

615 (3%)

 Very good

42,716 (40%)

1756 (9%)

 Good

25,755 (24%)

4915 (27%)

 Fair

6740 (6%)

7273 (39%)

 Poor

602 (1%)

3740 (20%)

Missing

517 (0%)

223 (1%)

“Overall, how are your problems now, compared to before your operation?” n (%)

 Much better

89,210 (83%)

2954 (16%)

 A little better

14,271 (13%)

6005 (32%)

 About the same

2286 (2%)

3489 (19%)

 A little worse

1237 (1%)

3227 (18%)

 Much worse

227 (0%)

2647 (14%)

Missing

331 (0%)

150 (1%)

Post-op OKS scorea

 Mean (SD)

38.2 (7)

17.8 (6)

 Median (IQR)

39 (11)

19 (8)

Missing

44 (0%)

2 (0%)

Standardised post-op OKS-Pain scoreb

 Mean (SD)

82.4 (14)

36.0 (12)

 Median (IQR)

85.7 (25.0)

39.3 (17.9)

Missing

0 (0%)

0 (0%)

Standardised post-op OKS-Function scorec

 Mean (SD)

75.4 (8)

38.8 (8)

 Median (IQR)

80 (25)

40 (20)

Missing

44 (0%)

2 (0%)

Post-op EQ-5D indexd

 Mean (SD)

0.792 (0.19)

0.395 (0.30)

 Median (IQR)

0.796 (0.309)

0.516 (0.532)

Missing

4934 (5%)

1150 (6%)

Post-op EQ-5D VASe “Your own health state today”

 Mean (SD)

76.9 (16)

55.1 (20)

 Median (IQR)

80 (20)

55 (30)

Missing

5413 (5%)

1333 (7%)

  1. acaptures knee pain and function, scored from 0 to 48 where 0 indicates most and 48 least pain and functional limitations
  2. bOKS Pain subscale as captured by seven questions, scored 0–100 where 0 indicates most and 100 least pain
  3. cOKS Function subscale as captured by five questions, scored 0–100 where 0 indicates most and 100 least functional limitations
  4. da health-related quality of life measure where 0 represents death and 1 refers to perfect health
  5. ea Visual Analogue Scale ranging from 0 to 100, where 0 represents the worst and 100 the best imaginable health state