Table 1.
Characteristics of patients who underwent cancer surgery according to hospital volume
| Variable | Hospital volumea | p-valueb | ||||
|---|---|---|---|---|---|---|
| Total | Very low | Low | High | Very high | ||
| Pneumonectomyc (n = 7,720) | (< 26) | (26–50) | (51–133) | (> 133) | ||
| Female gender | 2,340 (30.31) | 582 (30.81) | 565 (29.99) | 457 (27.48) | 736 (32.22) | < 0.05 |
| Age (y) | < 0.001 | |||||
| < 50 | 1,738 (22.51) | 471 (24.93) | 453 (24.04) | 280 (16.84) | 534 (23.38) | |
| 50–59 | 1,781 (23.07) | 391 (20.70) | 444 (23.57) | 395 (23.75) | 551 (24.12) | |
| 60–69 | 2,935 (38.02) | 688 (36.42) | 698 (37.05) | 697 (41.91) | 852 (37.30) | |
| > 69 | 1,266 (16.40) | 339 (17.95) | 289 (15.34) | 291 (17.50) | 347 (15.19) | |
| Contributiond | < 0.001 | |||||
| < 28,010 | 1,781 (23.07) | 558 (29.54) | 480 (25.48) | 387 (23.27) | 356 (15.59) | |
| 28,010–74,720 | 3,942 (51.06) | 944 (49.97) | 1,030 (54.67) | 861 (51.77) | 1,107 (48.47) | |
| > 74,720 | 1,997 (25.87) | 387 (20.49) | 374 (19.85) | 415 (24.95) | 821 (35.95) | |
| Residential area | < 0.001 | |||||
| Metropolitan | 5,048 (65.39) | 1,177 (62.31) | 1,176 (62.42) | 1,112 (66.87) | 1,583 (69.31) | |
| Urban | 1,838 (23.81) | 473 (25.04) | 493 (26.17) | 387 (23.27) | 485 (21.23) | |
| Rural | 834 (10.80) | 239 (12.65) | 215 (11.41) | 164 (9.86) | 216 (9.46) | |
| Routine admission | 6,537 (84.68) | 1,571 (83.17) | 1,432 (76.01) | 1,485 (89.30) | 2,049 (89.71) | < 0.001 |
| Charlson score | < 0.001 | |||||
| 0 | 3,277 (42.45) | 784 (41.50) | 907 (48.14) | 693 (41.67) | 893 (39.10) | |
| 1 | 1,786 (23.13) | 556 (29.43) | 522 (27.71) | 387 (23.27) | 321 (14.05) | |
| > 2 | 2,657 (34.42) | 549 (29.06) | 455 (24.15) | 583 (35.06) | 1,070 (46.85) | |
| Private ownership | 7,653 (99.13) | 1,822 (96.45) | 1,884 (100) | 1,663 (100) | 2,284 (100) | < 0.001 |
| Hospital location | < 0.001 | |||||
| Metropolitan | 7,206 (93.34) | 1,476 (78.14) | 1,783 (94.64) | 1,663 (100) | 2,284 (100) | |
| Urban | 338 (4.38) | 338 (17.89) | 0 (0) | 0 (0) | 0 (0) | |
| Rural | 176 (2.28) | 75 (3.97) | 101 (5.36) | 0 (0) | 0 (0) | |
| Hospital size (beds) | < 0.001 | |||||
| < 500 | 371 (4.81) | 185 (9.79) | 0 (0) | 186 (11.18) | 0 (0) | |
| 500–699 | 1,118 (14.48) | 612 (32.40) | 0 (0) | 506 (30.43) | 0 (0) | |
| > 699 | 6,231 (80.71) | 1,092 (57.81) | 1,884 (100) | 971 (58.39) | 2,284 (100) | |
| Teaching hospital | 6,944 (89.95) | 1,810 (95.82) | 1,884 (100) | 966 (58.09) | 2,284 (100) | < 0.001 |
| Colectomyc (n = 16,085) | (< 33) | (33–52) | (53–100) | (> 100) | ||
| Female gender | 7,117 (44.25) | 1,562 (42.90) | 1,960 (46.74) | 1,789 (43.68) | 1,806 (43.47) | < 0.01 |
| Age (y) | < 0.001 | |||||
| < 50 | 4,411 (27.42) | 1,077 (29.58) | 1,170 (27.90) | 1,057 (25.81) | 1,107 (26.64) | |
| 50–59 | 3,022 (18.79) | 622 (17.08) | 782 (18.65) | 739 (18.04) | 879 (21.16) | |
| 60–69 | 4,627 (28.77) | 934 (25.65) | 1,150 (27.43) | 1,249 (30.49) | 1,294 (31.14) | |
| > 69 | 4,025 (25.02) | 1,008 (27.68) | 1,091 (26.02) | 1,051 (25.66) | 875 (21.06) | |
| Contributiond | < 0.001 | |||||
| < 28,010 | 3,921 (24.38) | 1,007 (27.66) | 1,082 (25.80) | 1,035 (25.27) | 797 (19.18) | |
| 28,010–74,720 | 8,064 (50.13) | 1,823 (50.07) | 2,156 (51.42) | 2,092 (51.07) | 1,993 (47.97) | |
| > 74,720 | 4,100 (25.49) | 811 (22.27) | 955 (22.78) | 969 (23.66) | 1,365 (32.85) | |
| Residential area | < 0.001 | |||||
| Metropolitan | 10,486 (65.19) | 2,141 (58.80) | 2,683 (63.99) | 2,792 (68.16) | 2,870 (69.07) | |
| Urban | 3,909 (24.30) | 988 (27.14) | 1,134 (27.05) | 851 (20.78) | 936 (22.53) | |
| Rural | 1,690 (10.51) | 512 (14.06) | 376 (8.97) | 453 (11.06) | 349 (8.40) | |
| Routine admission | 11,194 (69.59) | 2,726 (74.87) | 2,742 (65.39) | 2,723 (66.48) | 3,003 (72.27) | < 0.001 |
| Charlson score | < 0.001 | |||||
| 0 | 8,165 (50.76) | 1,985 (54.52) | 2,053 (48.96) | 2,174 (53.08) | 1,953 (47.00) | |
| 1 | 3,580 (22.26) | 977 (26.83) | 987 (23.54) | 898 (21.92) | 718 (17.28) | |
| > 2 | 4,340 (26.98) | 679 (18.65) | 1,153 (27.50) | 1,024 (25.00) | 1,484 (35.72) | |
| Private ownership | 15,810 (98.29) | 3,463 (95.11) | 4,096 (97.69) | 4,096 (100) | 4,155 (100) | < 0.001 |
| Hospital location | < 0.001 | |||||
| Metropolitan | 13,763 (85.56) | 2,461 (67.59) | 3,222 (76.84) | 3,925 (95.83) | 4,155 (100) | |
| Urban | 1,976 (12.28) | 1,099 (30.18) | 706 (16.84) | 171 (4.17) | 0 (0) | |
| Rural | 346 (2.15) | 81 (2.22) | 265 (6.32) | 0 (0) | 0 (0) | |
| Hospital size (beds) | < 0.001 | |||||
| < 500 | 3,207 (19.94) | 2,348 (64.49) | 637 (15.19) | 222 (5.42) | 0 (0) | |
| 500–699 | 3,091 (19.22) | 1,011 (27.77) | 1,462 (34.87) | 215 (5.25) | 403 (9.70) | |
| > 699 | 9,787 (60.85) | 282 (7.75) | 2,094 (49.94) | 3,659 (89.33) | 3,752 (90.30) | |
| Teaching hospital | 13,530 (84.12) | 2,094 (57.51) | 3,588 (85.57) | 4,096 (100) | 3,752 (90.30) | < 0.001 |
| Mastectomyc (n = 33,225) | (< 70) | (70–142) | (142–357) | (> 357) | ||
| Female gender | 31,394 (94.49) | 7,120 (84.59) | 7,725 (96.42) | 7,934 (97.87) | 8,615 (99.15) | < 0.001 |
| Age (y) | < 0.001 | |||||
| < 50 | 21,266 (64.01) | 5,452 (64.77) | 5,216 (65.10) | 5,057 (62.38) | 5,541 (63.77) | |
| 50–59 | 7,170 (21.58) | 1,546 (18.37) | 1,709 (21.33) | 1,883 (23.23) | 2,032 (23.39) | |
| 60–69 | 3,618 (10.89) | 1,009 (11.99) | 817 (10.20) | 915 (11.29) | 877 (10.09) | |
| > 69 | 1,171 (3.52) | 410 (4.87) | 270 (3.37) | 252 (3.11) | 239 (2.75) | |
| Contributiond | < 0.001 | |||||
| < 28,010 | 8,049 (24.23) | 2,466 (29.30) | 1,967 (24.55) | 1,956 (24.13) | 1,660 (19.10) | |
| 28,010–74,720 | 16,423 (49.43) | 4,267 (50.70) | 4,042 (50.45) | 4,012 (49.49) | 4,102 (47.21) | |
| > 74,720 | 8,753 (26.34) | 1,684 (20.01) | 2,003 (25.00) | 2,139 (26.38) | 2,927 (33.69) | |
| Residential area | < 0.001 | |||||
| Metropolitan | 23,219 (69.88) | 4,978 (59.14) | 6,059 (75.62) | 5,940 (73.27) | 6,242 (71.84) | |
| Urban | 7,485 (22.53) | 2,500 (29.70) | 1,424 (17.77) | 1,658 (20.45) | 1,903 (21.90) | |
| Rural | 2,521 (7.59) | 939 (11.16) | 529 (6.61) | 509 (6.28) | 544 (6.26) | |
| Routine admission | 28,404 (85.49) | 7,091 (84.25) | 7,106 (88.69) | 7,652 (94.39) | 6,555 (75.44) | < 0.001 |
| Charlson score | < 0.001 | |||||
| 0 | 21,404 (64.42) | 5,526 (65.65) | 5,480 (68.40) | 5,998 (73.99) | 4,400 (50.64) | |
| 1 | 2,883 (8.68) | 994 (11.81) | 864 (10.78) | 581 (7.17) | 444 (5.11) | |
| > 2 | 8,938 (26.90) | 1,897 (22.54) | 1,668 (20.82) | 1,528 (18.85) | 3,845 (44.25) | |
| Private ownership | 32,889 (98.99) | 8,081 (96.01) | 8,012 (100) | 8,107 (100) | 8,689 (100) | < 0.001 |
| Hospital location | <0.001 | |||||
| Metropolitan | 30,441 (91.62) | 5,937 (70.54) | 7,708 (96.21) | 8,107 (100) | 8,689 (100) | |
| Urban | 2,156 (6.49) | 2,156 (25.61) | 0 (0.00) | 0 (0.00) | 0 (0.00) | |
| Rural | 628 (1.89) | 324 (3.85) | 304 (3.79) | 0 (0.00) | 0 (0.00) | |
| Hospital size (beds) | < 0.001 | |||||
| < 500 | 5,993 (18.04) | 3,207 (38.10) | 711 (8.87) | 661 (8.15) | 1,414 (16.27) | |
| 500–699 | 5,265 (15.85) | 2,761 (32.80) | 1,095 (13.67) | 1,409 (17.38) | 0 (0.00) | |
| > 699 | 21,967 (66.12) | 2,449 (29.10) | 6,206 (77.46) | 6,037 (74.47) | 7,275 (83.73) | |
| Teaching hospital | 28,939 (87.10) | 6,337 (75.29) | 7,215 (90.05) | 6,698 (82.62) | 8,689 (100) | < 0.001 |
| Cystectomyc (n = 1,688) | (< 25) | (25–42) | (42–72) | (> 72) | ||
| Female gender | 347 (20.56) | 67 (18.72) | 88 (19.38) | 88 (19.64) | 104 (24.30) | NS |
| Age (y) | <0.001 | |||||
| < 50 | 264 (15.64) | 59 (16.48) | 50 (11.01) | 61 (13.62) | 94 (21.96) | |
| 50–59 | 270 (16.00) | 42 (11.73) | 79 (17.40) | 79 (17.63) | 70 (16.36) | |
| 60–69 | 616 (36.49) | 111 (31.01) | 167 (36.78) | 178 (39.73) | 160 (37.38) | |
| > 69 | 538 (31.87) | 146 (40.78) | 158 (34.80) | 130 (29.02) | 104 (24.30) | |
| Contributiond | < 0.001 | |||||
| < 28,010 | 427 (25.30) | 105 (29.33) | 123 (27.09) | 122 (27.23) | 77 (17.99) | |
| 28,010–74,720 | 860 (50.95) | 181 (50.56) | 235 (51.76) | 227 (50.67) | 217 (50.70) | |
| > 74,720 | 401 (23.76) | 72 (20.11) | 96 (21.15) | 99 (22.10) | 134 (31.31) | |
| Residential area | NS | |||||
| Metropolitan | 1,122 (66.47) | 219 (61.17) | 295 (64.98) | 312 (69.64) | 296 (69.16) | |
| Urban | 378 (22.39) | 90 (25.14) | 104 (22.91) | 94 (20.98) | 90 (21.03) | |
| Rural | 188 (11.14) | 49 (13.69) | 55 (12.11) | 42 (9.38) | 42 (9.81) | |
| Routine admission | 1,381 (81.81) | 307 (85.75) | 378 (83.26) | 341 (76.12) | 355 (82.94) | < 0.01 |
| Charlson score | < 0.001 | |||||
| 0 | 818 (48.46) | 185 (51.68) | 194 (42.73) | 230 (51.34) | 209 (48.83) | |
| 1 | 475 (28.14) | 101 (28.21) | 142 (31.28) | 144 (32.14) | 88 (20.56) | |
| > 2 | 395 (23.40) | 72 (20.11) | 118 (25.99) | 74 (16.52) | 131 (30.61) | |
| Private ownership | 1,673 (99.11) | 346 (96.65) | 451 (99.34) | 448 (100) | 428 (100) | < 0.001 |
| Hospital location | < 0.001 | |||||
| Metropolitan | 1,521 (90.11) | 265 (74.02) | 380 (83.70) | 448 (100) | 428 (100) | |
| Urban | 134 (7.94) | 60 (16.76) | 74 (16.30) | 0 (0) | 0 (0) | |
| Rural | 33 (1.95) | 33 (9.22) | 0 (0) | 0 (0) | 0 (0) | |
| Hospital size (beds) | < 0.001 | |||||
| < 500 | 162 (9.60) | 117 (32.68) | 6 (1.32) | 39 (8.71) | 0 (0) | |
| 500–699 | 304 (18.01) | 151 (42.18) | 82 (18.06) | 71 (15.85) | 0 (0) | |
| > 699 | 1,222 (72.39) | 90 (25.14) | 366 (80.62) | 338 (75.45) | 428 (100) | |
| Teaching hospital | 1,590 (94.19) | 321 (89.66) | 451 (99.34) | 390 (87.05) | 428 (100) | < 0.001 |
| Esophagectomyc (n = 3,831) | (<13) | (13–36) | (37–94) | (>94) | ||
| Female gender | 337 (8.80) | 86 (9.36) | 84 (8.77) | 78 (8.29) | 89 (8.79) | NS |
| Age (y) | NS | |||||
| < 50 | 411 (10.73) | 111 (12.08) | 109 (11.38) | 83 (8.82) | 108 (10.66) | |
| 50–59 | 915 (23.88) | 205 (22.31) | 242 (25.26) | 224 (23.80) | 244 (24.09) | |
| 60–69 | 1,872 (48.86) | 431 (46.90) | 466 (48.64) | 484 (51.43) | 491 (48.47) | |
| > 69 | 633 (16.52) | 172 (18.72) | 141 (14.72) | 150 (15.94) | 170 (16.78) | |
| Contributiond | <0.001 | |||||
| < 28,010 | 1,061 (27.70) | 319 (34.71) | 298 (31.11) | 255 (27.10) | 189 (18.66) | |
| 28,010–74,720 | 2,059 (53.75) | 452 (49.18) | 490 (51.15) | 537 (57.07) | 580 (57.26) | |
| > 74,720 | 711 (18.56) | 148 (16.10) | 170 (17.75) | 149 (15.83) | 244 (24.09) | |
| Residential area | < 0.001 | |||||
| Metropolitan | 2,223 (58.03) | 529 (57.56) | 583 (60.86) | 518 (55.05) | 593 (58.54) | |
| Urban | 986 (25.74) | 233 (25.35) | 252 (26.30) | 239 (25.40) | 262 (25.86) | |
| Rural | 622 (16.24) | 157 (17.08) | 123 (12.84) | 184 (19.55) | 158 (15.60) | |
| Routine admission | 3,180 (83.01) | 735 (79.98) | 838 (87.47) | 734 (78.00) | 873 (86.18) | < 0.001 |
| Charlson score | < 0.001 | |||||
| 0 | 1,320 (34.46) | 286 (31.12) | 398 (41.54) | 245 (26.04) | 391 (38.60) | |
| 1 | 1,408 (36.75) | 293 (31.88) | 321 (33.51) | 444 (47.18) | 350 (34.55) | |
| >2 | 1,103 (28.79) | 340 (37.00) | 239 (24.95) | 252 (26.78) | 272 (26.85) | |
| Private ownership | 3,791 (98.96) | 879 (95.65) | 958 (100) | 941 (100) | 1,013 (100) | < 0.001 |
| Hospital location | < 0.001 | |||||
| Metropolitan | 3,586 (93.60) | 722 (78.56) | 910 (94.99) | 941 (100) | 1,013 (100) | |
| Urban | 163 (4.25) | 163 (17.74) | 0 (0) | 0 (0) | 0 (0) | |
| Rural | 82 (2.14) | 34 (3.70) | 48 (5.01) | 0 (0) | 0 (0) | |
| Hospital size (beds) | < 0.001 | |||||
| < 500 | 288 (7.52) | 53 (5.77) | 0 (0) | 235 (24.97) | 0 (0) | |
| 500–699 | 610 (15.92) | 237 (25.79) | 48 (5.01) | 325 (34.54) | 0 (0) | |
| > 699 | 2,933 (76.56) | 629 (68.44) | 910 (94.99) | 381 (40.49) | 1,013 (100) | |
| Teaching hospital | 3,400 (88.75) | 890 (96.84) | 881 (91.96) | 616 (65.46) | 1,013 (100) | < 0.001 |
Values are presented as number (%). NS, not significant.
a
To estimate average total hospital volume, we divided the observed Medicare volume (per year) by the proportion of Medicare patients undergoing each procedure (as determined by the Nationwide Inpatient Sample).
b
All p-values reflect two-sided comparisons within hospital volume groups, and were calculated using the chi-squared test.
c
Cutoffs for hospital volume quartiles are reported in parentheses.
d
Contribution unit Korean Won/month.