Table 1 Characteristics of patients undergoing percutaneous coronary intervention according to hospital volume of throughput, Scotland, 1997–2003.
| Low volume (<400 PCIs pa) n = 3756 | Medium volume (400–750 PCIs pa) n = 10 419 | High volume (>750 PCIs pa) n = 3242 | p Value* | |
|---|---|---|---|---|
| Age group (years) | ||||
| <56 | 1259 (34%) | 3426 (33%) | 925 (29%) | <0.001 |
| 56–65 | 1376 (37%) | 3594 (35%) | 1125 (35%) | |
| 66–75 | 942 (25%) | 2730 (26%) | 895 (28%) | |
| >75 | 179 (5%) | 669 (6%) | 297 (9%) | |
| Missing | 0 | 0 | 0 | |
| Sex | ||||
| Male | 2554 (68%) | 7202 (69%) | 2322 (72%) | 0.004 |
| Female | 1202 (32%) | 3212 (31%) | 920 (28%) | |
| Missing | 0 | 0 | 0 | |
| Urgency | ||||
| Emergency | 567 (15%) | 1120 (11%) | 288 (9%) | 0.006 |
| Urgent | 1285 (34%) | 3482 (33%) | 1387 (43%) | |
| Elective | 1904 (51%) | 5816 (56%) | 1567 (48%) | |
| Missing | 0 | 1 | 0 | |
| Indication | ||||
| Primary | 86 (2%) | 111 (1%) | 48 (2%) | <0.001 |
| Rescue | 223 (6%) | 193 (2%) | 125 (4%) | |
| Unstable angina | 1412 (39%) | 3916 (38%) | 1379 (43%) | |
| Stable angina | 1536 (42%) | 4820 (47%) | 1543 (48%) | |
| Other | 405 (11%) | 1212 (12%) | 147 (5%) | |
| Missing | 94 | 167 | 0 | |
| Number of arteries with ⩾70% stenosis | ||||
| 0 | 28 (1%) | 431 (5%) | 307 (10%) | <0.001 |
| 1 | 1690 (49%) | 4751 (50%) | 1603 (50%) | |
| 2 | 1126 (33%) | 2650 (28%) | 879 (27%) | |
| 3 | 509 (15%) | 1399 (15%) | 338 (11%) | |
| Left main stem | 79 (2%) | 261 (3%) | 90 (3%) | |
| Missing | 324 | 927 | 25 | |
| Left ventricular impairment | ||||
| None | 2143 (66%) | 5384 (58%) | 1525 (48%) | <0.001 |
| Mild/moderate | 1004 (31%) | 3680 (40%) | 1610 (51%) | |
| Severe | 89 (3%) | 183 (2%) | 51 (2%) | |
| Missing | 520 | 1172 | 56 | |
| Previous coronary revascularisation | ||||
| No | 2707 (80%) | 6774 (73%) | 2263 (76%) | <0.001 |
| Yes | 697 (21%) | 2592 (27%) | 736 (25%) | |
| Missing | 352 | 1153 | 243 | |
| Diabetes mellitus | ||||
| No | 3116 (90%) | 8095 (88%) | 2549 (86%) | <0.001 |
| Yes | 337 (10%) | 1154 (13%) | 415 (14%) | |
| Missing | 303 | 1170 | 278 | |
| Smoking status | ||||
| Non‐smoker | 1089 (33%) | 3323 (38%) | 1164 (40%) | <0.001 |
| Current smoker | 997 (30%) | 2473 (28%) | 953 (33%) | |
| Former smoker | 1238 (37%) | 3037 (34%) | 779 (27%) | |
| Missing | 432 | 1586 | 346 | |
| Obesity | ||||
| No | 2003 (77%) | 5331 (73%) | 1644 (71%) | <0.001 |
| Yes | 609 (23%) | 1983 (27%) | 678 (29%) | |
| Missing | 1144 | 3105 | 920 | |
| Hypertension | ||||
| No | 2272 (66%) | 5571 (63%) | 1610 (55%) | <0.001 |
| Yes | 1161 (34%) | 3318 (37%) | 1307 (45%) | |
| Missing | 323 | 1530 | 325 | |
| Hyperlipidaemia | ||||
| No | 1114 (33%) | 2701 (31%) | 723 (26%) | <0.001 |
| Yes | 2283 (67%) | 6129 (69%) | 2089 (74%) | |
| Missing | 359 | 1589 | 430 | |
| Deprivation quintile | ||||
| 1 (most affluent) | 821 (23%) | 1626 (16%) | 594 (19%) | <0.001 |
| 2 | 706 (20%) | 1798 (17%) | 518 (16%) | |
| 3 | 759 (21%) | 2094 (20%) | 608 (19%) | |
| 4 | 681 (19%) | 2181 (21%) | 719 (22%) | |
| 5 (most deprived) | 610 (17%) | 2657 (26%) | 774 (24%) | |
| Missing | 179 | 63 | 29 | |
*χ2 test for trend for ordinal variables (age group, urgency, left ventricular impairment and deprivation quintile), χ2 test for all other variables.
pa, per annum; PCI, percutaneous coronary intervention.