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. 2019 Jun;19(6):589–600. doi: 10.1016/S1473-3099(18)30755-2

Table.

Sample description and incidence rates

n Person-years of follow-up Cases Incidence rate per 1000 person-years (95% CI)
Patient characteristics
Sex
Female 386 047 1 913 858 1564 0·82 (0·78–0·86)
Male 292 963 1 418 437 2095 1·48 (1·41–1·54)
Age, years
<60 109 000 537 080 793 1·48 (1·38–1·58)
60–69 229 107 1 143 670 1342 1·17 (1·11–1·24)
70–79 247 636 1 233 478 1223 0·99 (0·94–1·05)
≥80 93 267 418 066 301 0·72 (0·64–0·81)
Ethnic origin
White 515 098 2 491 245 3066 1·23 (1·19–1·28)
Black African origin 6011 27 217 52 1·91 (1·43–2·51)
South Asian 15 510 69 500 94 1·35 (1·09–1·66)
Other and mixed 6513 28 414 40 1·41 (1·01–1·92)
Unclear 14 294 71 896 30 0·42 (0·28–0·60)
Unavailable* 121 584 644 023 377 0·59 (0·53–0·65)
BMI, kg/m2
<25 40 333 167 416 212 1·27 (1·10–1·45)
25–29·9 131 560 548 505 849 1·55 (1·45–1·66)
≥30 205 134 840 041 1558 1·85 (1·76–1·95)
Missing 301 983 1 776 333 1040 0·59 (0·55–0·62)
ASA grade
1 92 441 523 023 490 0·94 (0·86–1·02)
2 484 992 2 347 559 2460 1·05 (1·01–1·09)
3–5 101 577 461 713 709 1·54 (1·42–1·65)
Chronic pulmonary disease
No 478 788 2 350 416 2822 1·20 (1·16–1·25)
Yes 78 638 337 856 460 1·36 (1·24–1·49)
Unavailable* 121 584 644 023 377 0·59 (0·53–0·65)
Diabetes
No 490 521 2 398 439 2809 1·17 (1·13–1·22)
Yes 66 905 289 833 473 1·63 (1·49–1·79)
Unavailable* 121 584 644 023 377 0·59 (0·53–0·65)
Dementia
No 555 783 2 682 651 3274 1·22 (1·18–1·26)
Yes 1643 5621 8 1·42 (0·61–2·80)
Unavailable* 121 584 644 023 377 0·59 (0·53–0·65)
Liver disease
No 553 389 2 672 866 3237 1·21 (1·17–1·25)
Yes 4037 15 406 45 2·92 (2·13–3·91)
Unavailable* 121 584 644 023 377 0·59 (0·53–0·65)
Congestive heart failure
No 546 613 2 643 872 3211 1·21 (1·17–1·26)
Yes 10 813 44 399 71 1·60 (1·25–2·02)
Unavailable* 121 584 644 023 377 0·59 (0·53–0·65)
Connective tissue–rheumatic disease
No 526 493 2 547 415 3059 1·20 (1·16–1·24)
Yes 30 933 140 856 223 1·58 (1·38–1·81)
Unavailable* 121 584 644 023 377 0·59 (0·53–0·65)
Cancer
No 534 534 2 590 793 3170 1·22 (1·18–1·27)
Non-metastatic cancer 20 364 87 849 95 1·08 (0·87–1·32)
Metastatic cancer 2528 9629 17 1·77 (1·03–2·83)
Unavailable* 121 584 644 023 377 0·59 (0·53–0·65)
Cerebrovascular disease
No 546 047 2 640 626 3221 1·22 (1·18–1·26)
Yes 11 379 47 646 61 1·28 (0·98–1·64)
Unavailable* 121 584 644 023 377 0·59 (0·53–0·65)
Myocardial infarction
No 541 849 2 619 164 3186 1·22 (1·17–1·26)
Yes 15 577 69 107 96 1·39 (1·13–1·70)
Unavailable* 121 584 644 023 377 0·59 (0·53–0·65)
Paraplegia and hemiplegia
No 555 229 2 678 669 3263 1·22 (1·18–1·26)
Yes 2197 9603 19 1·98 (1·19–3·09)
Unavailable* 121 584 644 023 377 0·59 (0·53–0·65)
Peptic ulcer disease
No 549 071 2 649 116 3229 1·22 (1·18–1·26)
Yes 8355 39 155 53 1·35 (1·01–1·77)
Unavailable* 121 584 644 023 377 0·59 (0·53–0·65)
Peripheral vascular disease
No 547 096 2 645 530 3207 1·21 (1·17–1·25)
Yes 10 330 42 742 75 1·75 (1·38–2·20)
Unavailable* 121 584 644 023 377 0·59 (0·53–0·65)
Renal disease
No 539 605 2 628 852 3197 1·22 (1·17–1·26)
Yes 17 821 59 419 85 1·43 (1·14–1·77)
Unavailable* 121 584 644 023 377 0·59 (0·53–0·65)
Surgical characteristics
Osteoarthritis
No 18 529 92 371 157 1·70 (1·44–1·99)
Yes 660 481 3 239 923 3502 1·08 (1·05–1·12)
Trauma
No 675 193 3 313 911 3613 1·09 (1·05–1·13)
Yes 3817 18 383 46 2·50 (1·83–3·34)
Previous knee infection
No 678 522 3 329 986 3644 1·09 (1·06–1·13)
Yes 488 2309 15 6·50 (3·64–10·72)
Avascular necrosis
No 676 515 3 319 900 3638 1·10 (1·06–1·13)
Yes 2495 12 394 21 1·69 (1·05–2·59)
Inflammatory arthropathy
No 663 410 3 251 205 3534 1·09 (1·05–1·12)
Yes 15 600 81 089 125 1·54 (1·28–1·84)
Other indication
No 675 312 3 317 114 3636 1·10 (1·06–1·13)
Yes 3698 15 181 23 1·52 (0·96–2·27)
Surgical approach
Medial parapatellar 629 891 3 093 847 3 420 1·11 (1·07–1·14)
Midvastus 19 384 89 860 76 0·85 (0·67–1·06)
Lateral parapatellar 7992 42 506 47 1·11 (0·81–1·47)
Subvastus 9403 48 926 49 1·00 (0·74–1·32)
Other approach 12 340 57 155 67 1·17 (0·91–1·49)
Procedure
Primary TKR cemented 569 737 2 760 945 3227 1·17 (1·13–1·21)
Primary TKR uncemented 33 754 188 639 153 0·81 (0·69–0·95)
Primary TKR other 7699 48 490 52 1·07 (0·80–1·41)
Unicondylar 58 885 291 906 211 0·72 (0·63–0·83)
Patellofemoral 8935 42 314 16 0·38 (0·22–0·61)
Constraint
Unconstrained fixed 397 175 1 918 707 1987 1·04 (0·99–1·08)
Unconstrained mobile 47 532 262 875 278 1·06 (0·94–1·19)
Posterior stabilised fixed 144 960 705 782 981 1·39 (1·30–1·48)
Posterior stabilised mobile 9714 51 054 54 1·06 (0·79–1·38)
Constrained condylar 2968 11 498 43 3·74 (2·71–5·04)
Fixed 16 703 74 967 67 0·89 (0·69–1·14)
Mobile 41 297 212 086 141 0·66 (0·56–0·78)
Undetermined 18 661 95 326 108 1·13 (0·93–1·37)
General anaesthesia
No 381 156 1 788 490 1889 1·06 (1·01–1·10)
Yes 297 854 1 543 804 1770 1·15 (1·09–1·20)
Nerve block anaesthesia
No 547 783 2 644 393 2914 1·10 (1·06–1·14)
Yes 131 227 687 902 745 1·08 (1·01–1·16)
Epidural anaesthesia
No 621 572 2 987 043 3311 1·11 (1·07–1·15)
Yes 57 438 345 251 348 1·01 (0·90–1·12)
Spinal anaesthesia
No 283 120 1 499 422 1724 1·15 (1·10–1·21)
Yes 395 890 1 832 873 1935 1·06 (1·01–1·10)
Thromboprophylaxis regimen
Chemical 606 001 2 870 437 3204 1·12 (1·08–1·16)
Non-chemical 73 009 461 857 455 0·99 (0·90–1·08)
Femoral bone graft
No 675 147 3 317 925 3635 1·10 (1·06–1·13)
Yes 3863 14 370 24 1·67 (1·07–2·49)
Tibial bone graft
No 676 271 3 319 182 3629 1·09 (1·06–1·13)
Yes 2739 13 112 30 2·29 (1·54–3·27)
Intraoperative event
No 675 089 3 314 501 3636 ..
Yes 3921 17 794 23 1·29 (0·82–1·94)
Health system characteristics
Country of surgery
England 638 835 3 136 010 3461 1·10 (1·07–1·14)
Wales 40 175 196 285 198 1·01 (0·87–1·16)
Funding
NHS 574 433 2 722 013 3091 1·14 (1·10–1·18)
Private 75 507 395 514 362 0·92 (0·82–1·01)
Unspecified 29 070 214 768 206 0·96 (0·83–1·10)
Grade of operating surgeon
Consultant 572 464 2 767 937 3032 1·10 (1·06–1·14)
Other 106 546 564 357 627 1·11 (1·03–1·20)
Consultant involvement
Operating 572 464 2 767 937 3032 1·10 (1·06–1·14)
Assisting 38 327 188 754 223 1·18 (1·03–1·35)
Not involved 68 219 375 604 404 1·08 (0·97–1·19)
Total volume (operating surgeon) of knee replacements done in previous 12 months
≤25 173 288 988 694 1091 1·10 (1·04–1·17)
>25–50 160 104 815 890 983 1·20 (1·13–1·28)
>50–85 170 157 788 139 816 1·04 (0·97–1·11)
>85 175 461 739 571 769 1·04 (0·97–1·12)
Total volume (surgeon in charge) of knee replacements done in previous 12 months
≤38 173 204 1 010 739 1113 1·10 (1·04–1·17)
>38–70 174 209 872 816 986 1·13 (1·06–1·20)
>70–110 162 179 730 804 791 1·08 (1·01–1·16)
>110 169 418 717 936 769 1·07 (1·00–1·15)
Total volume (hospital) of knee replacements done in previous 12 months
≤150 167 930 1 008 852 984 0·98 (0·92–1·04)
>150–285 174 288 863 114 973 1·13 (1·06–1·20)
>285–440 169 780 743 102 893 1·20 (1·12–1·28)
>440 167 012 717 227 809 1·13 (1·05–1·21)

ASA=American Society of Anesthesiologists. TKR=total knee replacement. NHS=National Health Service.

*

Information about ethnicity and comorbidities is only available for the 557 426 patients operated on in England with a Hospital Episodes Statistics record, no record in the Patient Episode Database for Wales, and no evidence of residency outside England. See figure 1 and appendix p 2 for more details.