Table. Baseline Characteristics of Unmatched and Matched Cohortsa.
| Characteristic | All Patients (N = 27 904) | Unmatched Cohort | Matched Cohort | ||||
|---|---|---|---|---|---|---|---|
| Management at Index aSBO | Standardized Difference | Management at Index aSBO | Standardized Difference | ||||
| Nonoperative (n = 21 718) | Operative (n = 6186) | Nonoperative (n = 6160) | Operative (n = 6160) | ||||
| Age, mean (SD), y | 61.2 (13.6) | 61.5 (13.4) | 60.2 (14.3) | 0.10 | 61.1 (13.6) | 60.2 (14.3) | 0.06 |
| Female, No. (%) | 14 228 (51.0) | 10 653 (49.2) | 3575 (57.8) | 0.17 | 3656 (59.4) | 2599 (57.8) | 0.03 |
| Comorbidity burden, No. (%) | |||||||
| Healthy | 499 (1.8) | 350 (1.6) | 149 (2.4) | 0.06 | 122 (2.0) | 488 (2.4) | 0.03 |
| Low | 1294 (4.6) | 912 (4.2) | 382 (6.2) | 0.09 | 329 (5.3) | 380 (6.2) | 0.03 |
| Moderate | 9800 (35.2) | 7261 (33.5) | 2539 (41.0) | 0.16 | 2584 (42.0) | 2527 (41.0) | 0.02 |
| High | 6884 (24.7) | 5323 (24.6) | 1561 (25.2) | 0.02 | 1549 (25.2) | 1560 (25.3) | 0.02 |
| Very high | 9381 (33.7) | 7827 (36.1) | 1554 (25.1) | 0.24 | 1576 (25.6) | 1545 (25.1) | <0.01 |
| Income quintile, No. (%) | |||||||
| 1 (Lowest) | 5869 (21.1) | 4579 (21.1) | 1290 (20.9) | <0.01 | 1274 (20.7) | 1289 (20.9) | 0.01 |
| 2 | 5745 (20.6) | 4505 (20.8) | 1240 (20.1) | 0.02 | 1255 (20.4) | 1240 (20.1) | 0.01 |
| 3 | 5554 (19.9) | 4373 (20.2) | 1181 (19.1) | 0.03 | 1191 (19.3) | 1181 (19.2) | <0.01 |
| 4 | 5464 (19.6) | 4186 (19.3) | 1278 (20.7) | 0.03 | 1263 (20.5) | 1278 (20.7) | 0.01 |
| 5 (Highest) | 5092 (18.3) | 3920 (18.1) | 1172 (19.0) | 0.02 | 1177 (19.1) | 1172 (19.0) | <0.01 |
| Rural residence, No. (%) | 2211 (7.9) | 1872 (8.6) | 339 (5.5) | 0.12 | 275 (4.5) | 334 (5.4) | 0.04 |
| Hospital beds >250, No. (%) | 11 795 (42.3) | 8840 (40.8) | 2955 (47.8) | 0.14 | 2916 (47.3) | 2944 (47.8) | 0.01 |
| Teaching hospital, No. (%) | 6704 (24.1) | 5086 (23.5) | 1618 (26.2) | 0.06 | 1523 (24.7) | 1608 (26.1) | 0.03 |
| Weekend admission, No. (%) | 7556 (27.1) | 5848 (27.0) | 1708 (27.6) | 0.01 | 4575 (25.7) | 4464 (27.5) | 0.04 |
Abbreviation: aSBO, adhesive small-bowel obstruction.
a
Standardized differences are not effected by sample size, allowing for comparisons of baseline characteristics that are not affected by the smaller sample size after matching. A standardized difference of greater than 0.10 suggests negligible correlation between study groups (equivalent to P > .05).29