Table I.
Characteristics of study population
| Characteristic | No unplanned visit (n = 81,045) | Unplanned visit (n = 12,478) | P value |
|---|---|---|---|
| Age, y | |||
| 18–30 | 8,607 (11) | 1,602 (13) | |
| 31–45 | 28,444 (35) | 4,581 (37) | <.001 |
| 46–55 | 29,370 (36) | 4,178 (33) | |
| >55 | 14,624 (18) | 2,117 (17) | |
| Female | 33,748 (42) | 5,508 (44) | <.001 |
| Charlson score | |||
| 0 | 69,122 (85) | 10,113 (81) | |
| 1 | 9,468 (12) | 1,740 (14) | <.001 |
| ≥2 | 2,455 (3) | 625 (5) | |
| Income* | |||
| ≤$25,000 | 682 (1) | 117 (1) | |
| $25,000–40,000 | 19,496 (24) | 2,995 (24) | |
| $40,001–50,000 | 27,930 (34) | 4,245 (34) | .40 |
| $50,001–60,000 | 16,690 (21) | 2,530 (20) | |
| >$60,000 | 16,247 (20) | 2,591 (21) | |
| Education† | |||
| <75% | 10,036 (12) | 1,443 (12) | |
| 75–85% | 32,829 (41) | 5,006 (40) | .0238 |
| 85–90% | 25,721 (32) | 4,069 (33) | |
| >90% | 12,459 (15) | 1,960 (16) | |
| Region | |||
| Northeast | 7,519 (9) | 1,406 (11) | |
| North Central | 13,932 (17) | 2,438 (20) | |
| South | 50,101 (62) | 7,189 (58) | <.001 |
| West | 9,085 (11) | 1,375 (11) | |
| Unknown | 408 (1) | 70 (1) | |
| Procedure | |||
| SWL | 43,206 (53) | 5,800 (46) | |
| Ureteroscopy | 35,941 (44) | 6,339 (51) | <.001 |
| PNL | 1,898 (2) | 339 (3) | |
| High-volume facility‡ | 11,546 (14) | 1,431 (11) | <.001 |
*
Median household income.
†
Percent of population with at least high school diploma.
‡
Procedure-specific: ≥ 90th percentile for the procedure.
PNL, Percutaneous nephrostolithotomy; SWL, shock wave lithotripsy; URS, ureteroscopy.