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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