Table 1. Characteristics of patients in training sample by 30d readmission status.
| Variable | All Discharges N=4950 | Followed by Readmission N=978 | No Readmission N=3972 | P value |
|---|---|---|---|---|
| Age, N (%) | 0.47 | |||
| <50 years | 415 (8.4) | 99 (10.1) | 316 (8.0) | |
| 50-59 years | 955 (19.3) | 172 (17.6) | 783 (19.7) | |
| 60-69 years | 1541 (31.1) | 282 (28.8) | 1259 (31.7) | |
| 70+ years | 2039 (41.2) | 425 (43.5) | 1614 (40.6) | |
| Gender, N (%) | 0.54 | |||
| Female | 2322 (46.9) | 474 (48.5) | 1848 (46.5) | |
| Male | 2628 (53.1) | 504 (51.5) | 2124 (53.5) | |
| Marital status, N (%) | <0.001 | |||
| Married | 1969 (39.8) | 373 (38.1) | 1596 (40.2) | |
| Single | 2842 (57.4) | 593 (60.6) | 2249 (56.6) | |
| Other or unknown | 139 (2.8) | 12 (1.2) | 127 (3.2) | |
| Race/ethnicity, N (%) | <0.001 | |||
| Black | 1497 (30.2) | 365 (37.3) | 1132 (28.5) | |
| Hispanic | 463 (9.4) | 95 (9.7) | 368 (9.3) | |
| White | 1778 (35.9) | 252 (25.8) | 1526 (38.4) | |
| Other or unknown | 1212 (24.5) | 266 (27.2) | 946 (62.0) | |
| English speaking, N (%) | 0.35 | |||
| Yes | 4092 (82.7) | 814 (83.2) | 3278 (82.5) | |
| No | 858 (17.3) | 164 (16.8) | 694 (17.5) | |
| Insurance status, N (%) | ||||
| Medicaid | 574 (11.6) | 125 (12.8) | 449 (11.3) | <0.001 |
| Medicare | 2258 (45.6) | 440 (45.0) | 1818 (45.8) | |
| None | 119 (2.4) | 13 (1.3) | 106 (2.7) | |
| Private | 1074 (21.7) | 173 (17.7) | 901 (22.7) | |
| Unknown | 925 (18.7) | 227 (23.2) | 698 (17.6) | |
| Home zip code, N (%) | <0.001 | |||
| ≥5 miles from hospital | 2090 (42.2) | 263 (26.9) | 1827 (46.0) | |
| <5 miles from hospital | 2860 (57.8) | 715 (73.1) | 2145 (54.0) | |
| Education level, N (%) | <0.001 | |||
| Less than high school | 589 (11.9) | 122 (12.5) | 467 (11.8) | |
| Any high school | 2456 (49.6) | 603 (61.7) | 1853 (46.7) | |
| Some college | 339 (6.9) | 67 (6.9) | 272 (6.9) | |
| College graduate | 862 (17.4) | 120 (12.3) | 742 (18.7) | |
| Unknown | 704 (14.2) | 66 (6.8) | 638 (16.1) | |
| Employment, N (%) | <0.001 | |||
| Disabled | 850 (17.2) | 232 (23.7) | 618 (15.6) | |
| Employed | 533 (10.8) | 56 (5.7) | 477 (12.0) | |
| Retired | 2439 (49.3) | 515 (52.7) | 1924 (48.4) | |
| Unemployed | 915 (18.5) | 166 (18.1) | 749 (18.9) | |
| Other or unknown | 213 (4.3) | 9 (0.9) | 204 (5.1) | |
| Pre-admission sulfonylurea use, N (%) | 0.015 | |||
| Yes | 765 (15.5) | 180 (18.4) | 585 (14.7) | |
| No | 4185 (84.6) | 798 (81.6) | 3387 (85.3) | |
| Pre-admission metformin use, N (%) | <0.001 | |||
| Yes | 1283 (25.9) | 197 (20.1) | 1086 (27.3) | |
| No | 3667 (74.1) | 781 (79.9) | 2886 (72.7) | |
| Pre-admission thiazolidinedione use, N (%) | 0.014 | |||
| Yes | 358 (7.2) | 60 (6.1) | 298 (7.5) | |
| No | 4592 (92.8) | 918 (93.9) | 3674 (92.5) | |
| Pre-admission insulin use, N (%) | <0.001 | |||
| Yes | 1807 (36.5) | 444 (45.4) | 1363 (34.3) | |
| No | 3143 (63.5) | 534 (54.6) | 2609 (65.7) | |
| Pre-admission glucocorticoid use, N (%) | <0.001 | |||
| Yes | 330 (6.7) | 110 (11.3) | 220 (5.5) | |
| No | 4620 (93.3) | 868 (88.8) | 3752 (94.5) | |
| Most extreme blood glucose level, N (%) | <0.001 | |||
| 40-69 or 181-300 mg/dL | 2422 (48.9) | 482 (49.3) | 1940 (48.8) | |
| 70-180 mg/dL | 1757 (35.5) | 308 (31.5) | 1449 (36.5) | |
| <40 or >300 mg/dL | 771 (15.6) | 188 (19.2) | 583 (14.7) | |
| Diabetes inpatient consultation, N (%) | 0.30 | |||
| Yes | 743 (15.0) | 145 (14.8) | 598 (15.1) | |
| No | 4207 (85.0) | 833 (85.2) | 3374 (84.9) | |
| Current or prior DKA or HHS, N (%) | <0.001 | |||
| Yes | 142 (2.9) | 57 (5.8) | 85 (2.1) | |
| No | 4808 (97.1) | 921 (94.2) | 3887 (97.9) | |
| Microvascular complications,a N (%) | <0.001 | |||
| 0 | 3411 (68.9) | 550 (56.2) | 2861 (72.0) | |
| 1 | 918 (18.6) | 214 (21.9) | 704 (17.7) | |
| 2 | 398 (8.0) | 135 (13.8) | 263 (6.6) | |
| 3 | 223 (4.5) | 79 (8.1) | 144 (3.6) | |
| Macrovascular complications,b N (%) | <0.001 | |||
| 1 | 2258 (45.6) | 315 (32.2) | 1943 (48.9) | |
| 2 | 1956 (39.5) | 454 (46.4) | 1502 (37.8) | |
| 3 | 570 (11.5) | 160 (16.4) | 410 (10.3) | |
| 4 | 166 (3.4) | 49 (5.0) | 117 (3.0) | |
| Pre-admission BP meds, N (%) | <0.001 | |||
| None | 1085 (21.9) | 125 (12.8) | 960 (24.2) | |
| ACE-i or ARB | 2630 (53.1) | 553 (56.5) | 2077 (52.3) | |
| Non-ACE or ARB | 1235 (25.0) | 300 (30.7) | 935 (23.5) | |
| Pre-admission statin use, N (%) | <0.001 | |||
| Yes | 2931 (59.2) | 655 (67.0) | 2276 (57.3) | |
| No | 2019 (40.8) | 323 (33.0) | 1696 (42.7) | |
| White blood cell count, N (%) | 0.004 | |||
| Low <4 K/μL | 128 (2.6) | 39 (4.0) | 89 (2.2) | |
| Normal 4-11 k/μl | 4099 (82.8) | 794 (81.2) | 3305 (83.2) | |
| High >11 K/μL | 723 (14.6) | 145 (14.8) | 578 (14.6) | |
| Serum hematocrit (%), mean (SD) | 33.8 (5.4) | 32.9 (5.2) | 34.1 (5.4) | <0.001 |
| Serum albumin, N (%) | <0.001 | |||
| 4+ g/dL | 1478 (29.9) | 244 (25.0) | 1234 (31.1) | |
| <4 g/dL | 2728 (55.1) | 626 (64.0) | 2102 (52.9) | |
| Unknown | 744 (15.0) | 108 (11.0) | 636 (16.0) | |
| Serum sodium, N (%) | <0.001 | |||
| Low <135 mmol/L | 387 (7.8) | 90 (9.2) | 297 (7.5) | |
| Normal 135-145 mmol/L | 4500 (90.9) | 872 (89.2) | 3628 (91.3) | |
| High >145 mmol/L | 63 (1.3) | 16 (1.6) | 47 (1.2) | |
| Serum potassium, N (%) | 0.006 | |||
| Low <3.1 mmol/L | 27 (0.6) | 3 (0.3) | 24 (0.6) | |
| Normal 3.1-5.3 mmol/L | 4625 (93.4) | 895 (91.5) | 3730 (93.9) | |
| High >5.3 mmol/L | 298 (6.0) | 80 (8.2) | 218 (5.5) | |
| Creatinine (mg/dL), median (iQR) | 1.1 (0.9, 1.7) | 1.4 (0.9, 2.2) | 1.1 (0.8, 1.5) | <0.001 |
| Discharged 90 days prior to index admission, N (%) | <0.001 | |||
| Yes | 1401 (28.3) | 477 (48.8) | 924 (23.3) | |
| No | 3549 (71.7) | 501 (51.2) | 3048 (76.7) | |
| Urgent or emergent admission, N (%) | <0.001 | |||
| Yes | 4179 (84.4) | 869 (88.9) | 3310 (83.3) | |
| No | 771 (15.6) | 109 (11.2) | 662 (16.7) | |
| Intensive care admission, N (%) | 0.024 | |||
| Yes | 935 (18.9) | 164 (16.8) | 771 (19.4) | |
| No | 4015 (81.1) | 814 (83.2) | 3201 (80.6) | |
| Blood transfusion given, N (%) | 0.019 | |||
| Yes | 759 (15.3) | 158 (16.2) | 601 (15.1) | |
| No | 4191 (83.8) | 820 (19.6) | 3371 (84.9) | |
| Parenteral or enteral nutrition, N (%) | 0.022 | |||
| Yes | 99 (2.0) | 31 (3.2) | 68 (1.7) | |
| No | 4851 (98.0) | 947 (96.8) | 3904 (98.3) | |
| Discharge 1 year prior to index admission, N (%) | <0.001 | |||
| Home | 1633 (33.0) | 394 (40.3) | 1239 (31.2) | |
| Home with nursing care | 726 (14.7) | 211 (21.6) | 515 (13.0) | |
| Sub-acute facility | 459 (9.3) | 136 (13.9) | 323 (8.1) | |
| Against medical advice | 59 (1.2) | 24 (2.5) | 35 (0.9) | |
| No discharge recorded | 2073 (41.9) | 213 (21.8) | 1860 (46.8) | |
| Body mass index, N (%) | 0.097 | |||
| <18.5 kg/m2 | 70 (1.4) | 21 (2.2) | 49 (1.2) | |
| 18.5 – 24.9 kg/m2 | 632 (12.8) | 131 (13.4) | 501 (12.6) | |
| 25.0 – 29.9 kg/m2 | 1505 (30.4) | 277 (28.3) | 1228 (30.9) | |
| ≥30.0 kg/m2 | 2743 (55.4) | 549 (56.1) | 2194 (55.2) | |
| Schizophrenia or mood disorder ever, N (%) | <0.001 | |||
| Yes | 1011 (20.4) | 282 (28.8) | 729 (18.4) | |
| No | 3939 (79.6) | 696 (71.2) | 3243 (81.7) | |
| Gastroparesis ever, N (%) | 0.0053 | |||
| Yes | 139 (2.8) | 59 (6.0) | 80 (2.0) | |
| No | 4811 (97.2) | 919 (94.0) | 3892 (98.0) | |
| Pancreatitis ever, N (%) | 0.34 | |||
| Yes | 68 (1.4) | 11 (1.1) | 57 (1.4) | |
| No | 4882 (98.6) | 967 (98.9) | 3915 (98.6) | |
| Hypertension ever, N (%) | 0.0014 | |||
| Yes | 3938 (79.6) | 819 (83.7) | 3119 (78.5) | |
| No | 1012 (20.4) | 159 (16.3) | 853 (21.5) | |
| COPD or asthma ever, N (%) | <0.001 | |||
| Yes | 926 (18.7) | 262 (26.8) | 664 (16.7) | |
| No | 4024 (81.3) | 716 (73.2) | 3308 (83.3) | |
| Cardiac dysrhythmias ever, N (%) | <0.001 | |||
| Yes | 1693 (34.2) | 408 (41.7) | 1285 (32.4) | |
| No | 3257 (65.8) | 570 (58.3) | 2687 (67.6) | |
| Malignant neoplasm ever, N (%) | 0.41 | |||
| Yes | 213 (4.3) | 45 (4.6) | 168 (4.2) | |
| No | 4737 (95.7) | 933 (95.4) | 3804 (95.8) | |
| Anemia ever, N (%) | <0.001 | |||
| Yes | 1961 (39.6) | 524 (53.6) | 1437 (36.2) | |
| No | 2989 (60.4) | 454 (46.4) | 2535 (63.8) | |
| Drug abuse, N (%) | 0.19 | |||
| Never | 4163 (84.1) | 828 (84.7) | 3335 (84.0) | |
| History | 682 (13.8) | 125 (12.8) | 557 (14.0) | |
| Current | 105 (2.1) | 25 (2.6) | 80 (2.0) | |
| Current infection,c N (%) | <0.001 | |||
| Yes | 727 (14.7) | 183 (18.7) | 544 (13.7) | |
| No | 4223 (85.3) | 795 (81.3) | 3428 (86.3) | |
| Current complication of device, graft, or implant, N (%) | 0.94 | |||
| Yes | 115 (2.3) | 22 (2.3) | 93 (2.3) | |
| No | 4835 (97.7) | 956 (97.8) | 3879 (97.7) | |
| Current fluid or electrolyte disorder, N (%) | <0.001 | |||
| Yes | 579 (11.7) | 157 (16.1) | 422 (10.6) | |
| No | 4371 (88.3) | 821 (84.0) | 3550 (89.4) |
a
Retinopathy, neuropathy, nephropathy
b
Coronary artery disease, heart failure, stroke, peripheral vascular disease
c
Pneumonia, urinary tract infection, septicemia, skin or subcutaneous infection; COPD, chronic obstructive pulmonary disease