Baseline characteristics of patients in the QResearch derivation cohort, the QResearch validation cohort and the CPRD validation cohort
| QResearch derivation (n=2 849 381) | QResearch validation (n=1 340 622) | CPRD validation (n=2 475 360) | |
|---|---|---|---|
| Female | 1 446 784 (50.8) | 677 897 (50.6) | 1 260 015 (50.9) |
| Male | 1 402 597 (49.2) | 662 725 (49.4) | 1 215 345 (49.1) |
| Mean age (SD) | 46.3 (18.9) | 47.8 (18.6) | 48.2 (18.6) |
| Strategic Health Authority | |||
| East Midlands SHA | 225 092 (7.9) | 165 734 (12.4) | 70 695 (2.9) |
| Yorkshire & Humberside SHA | 220 560 (7.7) | 75 976 (5.7) | 287 374 (11.6) |
| East of England SHA | 197 453 (6.9) | 158 962 (11.9) | 390 573 (15.8) |
| London SHA | 560 544 (19.7) | 234 346 (17.5) | 52 618 (2.1) |
| North East SHA | 141 974 (5.0) | 103 200 (7.7) | 398 889 (16.1) |
| North West SHA | 268 958 (9.4) | 264 508 (19.7) | 317 867 (12.8) |
| South Central SHA | 310 830 (10.9) | 74 588 (5.6) | 274 296 (11.1) |
| South East SHA | 253 288 (8.9) | 63 455 (4.7) | 314 779 (12.7) |
| South West SHA | 421 052 (14.8) | 92 822 (6.9) | 275 566 (11.1) |
| West Midlands SHA | 249 630 (8.8) | 107 031 (8.0) | 92 703 (3.7) |
| Ethnicity | |||
| Ethnicity recorded | 2 129 124 (74.7) | 1 015 630 (75.8) | 1 301 115 (52.6) |
| White/not recorded | 2 554 557 (89.7) | 1 212 057 (90.4) | 2 320 487 (93.7) |
| Indian | 49 360 (1.7) | 22 888 (1.7) | 31 800 (1.3) |
| Pakistani | 23 947 (0.8) | 15 243 (1.1) | 13 739 (0.6) |
| Bangladeshi | 22 309 (0.8) | 11 076 (0.8) | 4482 (0.2) |
| Other Asian | 38 463 (1.3) | 14 870 (1.1) | 22 394 (0.9) |
| Caribbean | 23 704 (0.8) | 9038 (0.7) | 11 086 (0.4) |
| Black African | 43 471 (1.5) | 22 355 (1.7) | 26 533 (1.1) |
| Chinese | 28 803 (1.0) | 8086 (0.6) | 7514 (0.3) |
| Other | 64 767 (2.3) | 25 009 (1.9) | 37 325 (1.5) |
| Smoking status | |||
| Smoking status recorded | 2 766 234 (97.1) | 1 300 728 (97.0) | 2 388 744 (96.5) |
| Non-smoker | 1 568 956 (55.1) | 731 480 (54.6) | 1 220 054 (49.3) |
| Ex-smoker | 612 156 (21.5) | 288 031 (21.5) | 642 110 (25.9) |
| Light smoker (1–9/day) | 353 026 (12.4) | 165 471 (12.3) | 161 185 (6.5) |
| Moderate smoker (10–19/day) | 152 631 (5.4) | 75 157 (5.6) | 210 441 (8.5) |
| Heavy smoker (20+/day) | 79 465 (2.8) | 40 589 (3.0) | 120 768 (4.9) |
| Smoker amount not recorded | n/a | n/a | 34 186 (1.4) |
| Alcohol intake | |||
| Alcohol status recorded | 2 340 360 (82.1) | 1 097 278 (81.8) | 1 968 156 (79.5) |
| Non-drinker | 746 788 (26.2) | 354 328 (26.4) | 393 692 (15.9) |
| Trivial <1 unit/day | 792 730 (27.8) | 368 465 (27.5) | 878 965 (35.5) |
| Light 1–2 units/day | 365 897 (12.8) | 166 881 (12.4) | 508 687 (20.6) |
| Moderate 3–6 units/day | 387 161 (13.6) | 183 738 (13.7) | 150 466 (6.1) |
| Heavy 7–9 units/day | 27 501 (1.0) | 13 579 (1.0) | 17 695 (0.7) |
| Very Heavy >9 units/day | 16 260 (0.6) | 8112 (0.6) | 18 651 (0.8) |
| Drinker—amount not recorded | 4023 (0.1) | 2175 (0.2) | 0 (0) |
| Emergency admissions in the past year (HES record) | |||
| No emergency admission (HES record) | 2 695 651 (94.6) | 1 264 555 (94.3) | 2 334 640 (94.3) |
| 1 emergency admission (HES record) | 118 002 (4.1) | 58 078 (4.3) | 107 182 (4.3) |
| 2 emergency admissions (HES record) | 23 301 (0.8) | 11 687 (0.9) | 21 802 (0.9) |
| 3+ emergency admissions (HES record) | 12 427 (0.4) | 6302 (0.5) | 11 736 (0.5) |
| Emergency admissions in the past year (GP record) | |||
| No emergency admission (GP record) | 2 731 533 (95.9) | 1 283 422 (95.7) | 2 261 885 (91.4) |
| 1 emergency admission (GP record) | 89 457 (3.1) | 44 263 (3.3) | 158 723 (6.4) |
| 2 emergency admissions (GP record) | 19 581 (0.7) | 8812 (0.7) | 36 567 (1.5) |
| 3+ emergency admissions (GP record) | 8810 (0.3) | 4125 (0.3) | 18 185 (0.7) |
| Clinical values, family history and deprivation | |||
| Body mass index recorded | 2 281 550 (80.1) | 1 083 278 (80.8) | 1 980 327 (80.0) |
| Mean body mass index (SD) | 26.1 (4.9) | 26.4 (4.9) | 26.4 (5.0) |
| Systolic blood pressure recorded* | 2 437 745 (85.6) | 1 186 261 (88.5) | n/a |
| Mean systolic blood pressure (SD) | 127.0 (16.4) | 127.3 (16.5) | n/a |
| Cholesterol/HDL recorded* | 824 938 (29.0) | 413 117 (30.8) | n/a |
| Mean cholesterol/HDL ratio | 3.8 (1.2) | 3.8 (1.2) | n/a |
| Family history CHD* | 327 668 (11.5) | 169 286 (12.6) | n/a |
| Mean Townsend score (SD) | 0.1 (3.6) | 0.1 (3.5) | −0.7 (3.1) |
| Haemoglobin recorded | 1 645 857 (57.8) | 816 261 (60.9) | 1 512 841 (61.1) |
| Haemoglobin < 11 g/dl | 56 293 (2.0) | 28 113 (2.1) | 49 339 (2.0) |
| Platelets recorded | 1 632 357 (57.3) | 810 551 (60.5) | 1 505 945 (60.8) |
| Platelets > 480 | 16 501 (0.6) | 8434 (0.6) | 14 127 (0.6) |
| Liver function test recorded | 1 225 813 (43.0) | 628 439 (46.9) | 1 148 893 (46.4) |
| Abnormal liver function tests | 34 260 (1.2) | 19 112 (1.4) | 32 230 (1.3) |
| ESR recorded | 755 536 (26.5) | 409 183 (30.5) | n/a |
| Abnormal ESR | 5989 (0.2) | 3306 (0.2) | n/a |
| Comorbidity | |||
| Type 1 diabetes | 11 000 (0.4) | 5445 (0.4) | 9854 (0.4) |
| Type 2 diabetes | 125 374 (4.4) | 63 461 (4.7) | 117 754 (4.8) |
| Atrial fibrillation | 52 603 (1.8) | 26 285 (2.0) | 48 490 (2.0) |
| Cardiovascular disease | 154 825 (5.4) | 79 116 (5.9) | 150 108 (6.1) |
| Congestive cardiac failure | 27 404 (1.0) | 14 304 (1.1) | 22 685 (0.9) |
| Venous thromboembolism | 42 870 (1.5) | 21 298 (1.6) | 37 925 (1.5) |
| Cancer | 97 279 (3.4) | 48 370 (3.6) | 82 513 (3.3) |
| Asthma or COPD | 378 048 (13.3) | 179 635 (13.4) | 342 371 (13.8) |
| Epilepsy | 36 615 (1.3) | 17 904 (1.3) | 34 607 (1.4) |
| Falls | 124 248 (4.4) | 64 299 (4.8) | 172 555 (7.0) |
| Manic depression or schizophrenia | 21 277 (0.7) | 10 155 (0.8) | 16 792 (0.7) |
| Chronic renal disease | 9841 (0.3) | 4700 (0.4) | 9476 (0.4) |
| Conditions leading to malabsorption | 29 206 (1.0) | 14 432 (1.1) | 19 078 (0.8) |
| Chronic liver disease or pancreatitis | 15 811 (0.6) | 7669 (0.6) | 10 895 (0.4) |
| Valvular heart disease* | 30 924 (1.1) | 15 960 (1.2) | n/a |
| Treated hypertension* | 371 503 (13.0) | 188 901 (14.1) | n/a |
| Rheumatoid arthritis or SLE* | 45 966 (1.6) | 23 020 (1.7) | n/a |
| Depression (QOF definition)* | 372 341 (13.1) | 176 638 (13.2) | n/a |
| Current prescribed medication | |||
| Statins* | 341 765 (12.0) | 174 252 (13.0) | |
| NSAIDs | 416 749 (14.6) | 208 936 (15.6) | 365 927 (14.8) |
| Anticoagulants | 38 790 (1.4) | 19 764 (1.5) | 36 166 (1.5) |
| Corticosteroids | 101 067 (3.5) | 49 683 (3.7) | 109 847 (4.4) |
| Antidepressants | 341 194 (12.0) | 168 305 (12.6) | 302 457 (12.2) |
| Antipsychotics | 74 039 (2.6) | 38 324 (2.9) | 69 498 (2.8) |
Values are numbers (percentages of total number in cohort) unless stated otherwise.
CPRD, Clinical Practice Research DataLink; COPD, chronic obstructive pulmonary disease; CHD, coronary heart disease; ESR, erythrocyte sedimentation rate; GP, general practitioner; HES, hospital episode statistics; HDL, high-density lipoprotein; NSAIDs, non-steroidal anti-inflammatory drugs; SHA, Strategic Health Authority; SLE, systemic lupus erythematosus
*Variables which were considered but did not meet the criteria for inclusion in the final model. These variables were therefore not needed from CPRD for the external validation, so they have been reported as not applicable.