Table 2.
Baseline characteristics according to 31-180-day readmission
| Characteristic | All patients (n=6497) | Hospital Frailty Risk Score |
Adjusted P value∗ |
||
|---|---|---|---|---|---|
| Low (n=2976) | Intermediate (n=2898) | High (n=623) | |||
| Patient characteristics | |||||
| Age, y | 75 (70-81) | 75 (70-81) | 75 (69-81) | 75 (70-81) | 0.26 |
| Women | 1816 (28) | 762 (26) | 860 (30) | 194 (31) | <0.001 |
| Nonelective admission | 4828 (74) | 1803 (61) | 2458 (85) | 567 (91) | <0.001 |
| Weekend admission | 1181 (18) | 401 (13) | 629 (22) | 151 (24) | <0.001 |
| Median zip code income† | |||||
| 76-100th percentile | 1192 (19) | 514 (18) | 529 (19) | 149 (24) | 0.006 |
| 51-75th percentile | 1559 (24) | 691 (24) | 720 (25) | 148 (24) | |
| 26-50th percentile | 1845 (29) | 841 (29) | 825 (29) | 179 (29) | |
| 0-25th percentile | 1796 (28) | 878 (30) | 780 (27) | 138 (22) | |
| Expected primary payer | |||||
| Medicare | 5673 (87) | 2581 (87) | 2541 (88) | 551 (88) | 0.42 |
| Medicaid | 88 (1.4) | 39 (1.3) | 42 (1.4) | <11 (1.3) | |
| Private | 489 (7.5) | 250 (8.4) | 193 (6.7) | 46 (8.3) | |
| Others | 247 (3.8) | 106 (3.6) | 122 (4.2) | 19 (3.4) | |
| Comorbidities | |||||
| Smoking | 2082 (32) | 861 (29) | 1011 (35) | 210 (34) | <0.001 |
| Dyslipidemia | 4563 (70) | 2190 (74) | 1969 (68) | 404 (65) | <0.001 |
| Hypertension | 5628 (87) | 2517 (85) | 2565 (89) | 546 (88) | <0.001 |
| Diabetes mellitus | 2752 (42) | 1147 (39) | 1316 (45) | 289 (46) | <0.001 |
| Previous myocardial infarction | 1408 (22) | 659 (22) | 626 (22) | 123 (20) | 0.63 |
| Cardiac arrhythmias | 2774 (43) | 1031 (35) | 1392 (48) | 351 (56) | <0.001 |
| Previous PCI | 1186 (18) | 611 (21) | 467 (16) | 108 (17) | <0.001 |
| Previous CABG | 798 (12) | 440 (15) | 294 (10) | 64 (10) | <0.001 |
| Valvular disease | 1805 (28) | 715 (24) | 887 (31) | 203 (33) | <0.001 |
| Previous cerebrovascular disease | 804 (12) | 289 (9.7) | 373 (13) | 142 (23) | <0.001 |
| Fluid and electrolyte disorders | 17 (0.3) | <11 (0.1) | <11 (0.3) | <11 (0.6) | 0.05 |
| Peripheral vascular disease | 1237 (19) | 510 (17) | 592 (20) | 135 (22) | 0.003 |
| Chronic pulmonary disease | 1722 (27) | 649 (22) | 865 (30) | 208 (33) | <0.001 |
| Renal disease | 2305 (35) | 606 (20) | 1360 (47) | 339 (54) | <0.001 |
| Obesity | 1068 (16) | 414 (14) | 525 (18) | 129 (21) | <0.001 |
| Peptic ulcer disease | 44 (0.7) | <11 (0.2) | 28 (1.0) | <11 (1.4) | <0.001 |
| Rheumatic disease | 169 (2.6) | 68 (2.3) | 87 (3.0) | 14 (2.2) | 0.25 |
| Liver disease | 167 (2.6) | 50 (1.7) | 84 (2.9) | 33 (5.3) | <0.001 |
| Cancer | 361 (5.6) | 138 (4.6) | 189 (6.5) | 34 (5.5) | 0.001 |
| Anemia | 1887 (29) | 494 (17) | 1107 (38) | 286 (46) | <0.001 |
| Charlson Comorbidity Index | 3.5 ± 2.4 | 2.7 ± 2.1 | 4.0 ± 2.4 | 4.8 ± 2.6 | <0.001 |
| 0 | 352 (5.4) | 270 (9.1) | 73 (2.5) | <11 (1.4) | <0.001 |
| 1 | 1100 (17) | 673 (23) | 366 (13) | 61 (9.8) | |
| 2 | 1109 (17) | 676 (23) | 384 (13) | 49 (7.9) | |
| ≥3 | 3936 (61) | 1357 (46) | 2075 (72) | 504 (81) | |
| Elixhauser Comorbidity Score | 12.5 ± 7.6 | 9.6 ± 6.7 | 14.4 ± 7.2 | 17.8 ± 8.2 | <0.001 |
| ≤0 | 451 (6.9) | 367 (12) | 79 (2.7) | <11 (0.8) | <0.001 |
| 1-5 | 609 (9.4) | 378 (13) | 205 (7.1) | 26 (4.2) | |
| 6-10 | 1542 (24) | 931 (31) | 528 (18) | 83 (13) | |
| ≥11 | 3895 (60) | 1300 (44) | 2086 (72) | 509 (82) | |
| Hospital Frailty Risk Score | 6.8 ± 5.8 | 2.1 ± 1.5 | 9.0 ± 2.8 | 19.3 ± 4.1 | <0.001 |
| Diagnosis on admission | |||||
| STEMI | 943 (15) | 387 (13) | 450 (16) | 106 (17) | 0.001 |
| NSTEMI | 1890 (29) | 675 (23) | 1016 (35) | 199 (32) | <0.001 |
| Chronic coronary syndrome | 1998 (31) | 1365 (46) | 568 (20) | 65 (10) | <0.001 |
| Malignant arrhythmias/cardiac arrest | 334 (5.1) | 140 (4.7) | 163 (5.6) | 31 (5.0) | 0.35 |
| Heart failure and cardiogenic shock | 668 (10) | 205 (6.9) | 373 (13) | 90 (14) | <0.001 |
| Hospital characteristics | |||||
| Resident in same hospital state | 5918 (91) | 2696 (91) | 2642 (91) | 580 (93) | 0.38 |
| Teaching status of hospital | |||||
| Metropolitan teaching | 5145 (79) | 2254 (76) | 2374 (82) | 517 (83) | <0.001 |
| Metropolitan nonteaching | 1134 (17) | 597 (20) | 443 (15) | 94 (15) | |
| Nonmetropolitan hospital | 218 (3.4) | 125 (4.2) | 81 (2.8) | 12 (1.9) | |
| Hospital urban-rural designation | |||||
| Large metropolitan areas with at least 1 million residents | 3535 (54) | 1487 (50) | 1640 (57) | 408 (65) | <0.001 |
| Small metropolitan areas with <1 million residents | 2744 (42) | 1364 (46) | 1177 (41) | 203 (33) | |
| Micropolitan areas | 208 (3.2) | 123 (4.1) | 77 (2.7) | <11 (1.3) | |
| Not metropolitan or micropolitan (nonurban residual) | <11 (0.2) | <11 (0.07) | <11 (0.1) | <11 (0.6) | |
| Hospital bed size | |||||
| Small | 577 (8.9) | 296 (9.9) | 229 (7.9) | 52 (8.3) | 0.45 |
| Medium | 1647 (25) | 757 (25) | 723 (25) | 167 (27) | |
| Large | 4273 (66) | 1923 (65) | 1946 (67) | 404 (65) | |
| In-hospital procedures | |||||
| PCI | 5135 (79) | 2478 (83) | 2200 (76) | 457 (73) | <0.001 |
| CABG | 413 (6.4) | 131 (4.4) | 231 (8.0) | 51 (8.2) | <0.001 |
| Year of Impella procedure | |||||
| 2016 (January-November) | 726 (11) | 356 (12) | 327 (11) | 43 (6.9) | 0.03 |
| 2017 (January-November) | 1082 (17) | 507 (17) | 473 (16) | 101 (16) | |
| 2018 (January-November) | 1509 (23) | 706 (24) | 653 (23) | 150 (24) | |
| 2019 (January-November) | 1731 (27) | 773 (26) | 783 (27) | 175 (28) | |
| 2020 (January-November) | 1450 (22) | 634 (21) | 662 (23) | 154 (25) | |
| In-hospital complications | |||||
| Bleeding complications | 377 (5.8) | 112 (3.8) | 221 (7.6) | 44 (7.1) | <0.001 |
| Vascular complications | 102 (1.6) | 31 (1.0) | 58 (2.0) | 13 (2.1) | 0.003 |
| Stroke | 145 (2.2) | <11 (0.3) | 89 (3.1) | 48 (7.7) | <0.001 |
| Length of stay, median, d | 8 (3-15) | 4 (2-7) | 11 (7-18) | 21 (14-31) | <0.001 |
| ≤8 d | 3466 (53) | 2369 (80) | 1048 (36) | 49 (7.9) | <0.001 |
| >8 d | 3031 (47) | 607 (20) | 1850 (64) | 574 (92) | |
| Index cost (USD)‡ | 65,188 (46,546-93,362) | 52,705 (39,431-70,949) | 75,251 (55,319-106,289) | 104,724 (75,540-147,610) | <0.001 |
| Discharge destination | |||||
| Home (self-care) | 3146 (48) | 2068 (70) | 996 (34) | 82 (13) | <0.001 |
| Short-term hospital | 206 (3.2) | 64 (2.2) | 120 (4.1) | 22 (3.5) | |
| Transfer to other institution§ | 1617 (25) | 297 (10) | 994 (34) | 326 (52) | |
| Home health care | 1499 (23) | 537 (18) | 775 (27) | 187 (30) | |
| Against medical advice | 21 (0.3) | <11 (0.3) | <11 (0.3) | <11 (0.6) | |
Values are expressed as mean ± standard deviation, median (interquartile range), or counts (%) unless otherwise noted. Exact counts for variables with <11 patients are not detailed per the Healthcare Cost and Utilization Project data use agreement. Boldface indicates statistical significance (P < .05).
CABG, coronary artery bypass surgery; CI, confidence interval; MAE, major adverse event; NSTEMI, non–ST elevation myocardial infarction; OR, odds ratio; PCI, percutaneous coronary intervention; STEMI, ST-elevation myocardial infarction; USD, US dollar.
∗
Adjusted P values for each variable were computed from adjusting sampling design by discharge-level weights, cluster, and strata.
†
Median zip code income was missing in 1.5%.
‡
Index cost was missing in 0.1%.
§
Other institutions included skilled nursing facilities, intermediate care, or other types of facilities not elsewhere included.