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Table 1 Cohort description

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

Observations: n

126,064

Gender: n (%)

 Female

68,114 (54%)

 Male

49,306 (39%)

 Not specified

106 (0%)

 Missing

8538 (7%)

Age band: n (%)

 40–49 years of age

258 (0%)

 50–59 years of age

11,380 (9%)

 60–69 years of age

43,583 (35%)

 70–79 years of age

48,073 (38%)

 80–89 years of age

14,226 (11%)

 90+ years of age

6 (0%)

 Missing

8538 (7%)

Pre-op OKS score1

 Mean (SD)

19.0 (8)

 Median (IQR)

19 (11)

 Missing

1473 (1%)

Pre-op EQ-5D index2

 Mean (SD)

0.414(0.31)

 Median (IQR)

0.587 (0.603)

 Missing

7077 (6%)

Pre-op EQ-5D VAS3 “Your own health state today”

 Mean (SD)

68.2(20)

 Median (IQR)

70 (25)

 Missing

13,110 (10%)

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

 Excellent

31,827 (25%)

 Very good

44,472 (35%)

 Good

30,670 (24%)

 Fair or Poor

18,355 (15%)

 Missing

740 (1%)

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

 Much better

92,164 (73%)

 A little better

20,276 (16%)

 About the same

5775 (5%)

 A little or much worse

7388 (6%)

 Missing

461 (0%)

Post-op OKS scorea

 Mean (SD)

35.2 (10)

 Median (IQR)

37 (14)

 Missing

46 (0%)

Post-op EQ-5D indexb

 Mean (SD)

0.734(0.25)

 Median(IQR)

0.760 (0.344)

 Missing

6084 (5%)

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

 Mean (SD)

73.8 (20)

 Median (IQR)

80 (25)

 Missing

6746 (5%)

  1. acaptures knee pain and function, scored from 0 to 48 where 0 indicates most and 48 least pain and functional limitations
  2. ba health-related quality of life measure where 0 represents death and 1 refers to perfect health
  3. ca Visual Analogue Scale ranging from 0 to 100, where 0 represents the worst and 100 the best imaginable health state