Supplemental data
Table 1- ICD-9-CM and 10-CM coding strategies to identify common general surgery procedures including appendectomy, cholecystectomy, colectomy, and hernia repair.
Appendectomy Cholecystectomy Colectomy Hernia repair
ICD-9 ICD-10 ICD-9 ICD-10 ICD-9 ICD-10 ICD-9 ICD-10
470 0DTJ0ZZ 512 0F540ZZ 1731 0DBE0ZZ 0DBN0ZZ 5351 0WQF0ZZ
4701 0DTJ4ZZ 5121 0F543ZZ 1732 0DBE3ZZ 0DBN3ZZ 5359 0WQF3ZZ
4709 0DTJ7ZZ 5122 0FB40ZZ 1733 0DBE4ZZ 0DBN4ZZ 5361 0WQF4ZZ
4711 5123 0FB43ZZ 1734 0DBE7ZZ 0DBN7ZZ 5362 0WUF07Z
4719 5124 0FT40ZZ 1735 0DBF0ZZ 0DTE0ZZ 5363 0WUF0JZ
0FT44ZZ 1736 0DBF3ZZ 0DTE4ZZ 5369 0WUF0KZ
0F544ZZ 1737 0DBF4ZZ 0DTE7ZZ 0WUF47Z
0FB44ZZ 1738 0DBF7ZZ 0DTF0ZZ 0WUF4JZ
1739 0DBG0ZZ 0DTF4ZZ 0WUF4KZ
1741 0DBG3ZZ 0DTF7ZZ 1742 0DBG4ZZ 0DTG0ZZ 4570 0DBG7ZZ 0DTG4ZZ 4571 0DBH0ZZ 0DTG7ZZ 4572 0DBH3ZZ 0DTH0ZZ 4573 0DBH4ZZ 0DTH4ZZ 4574 0DBH7ZZ 0DTH7ZZ 4575 0DBK0ZZ 0DTK0ZZ 4576 0DBK3ZZ 0DTK4ZZ 4579 0DBK4ZZ 0DTK7ZZ 4580 0DBK7ZZ 0DTL0ZZ 4581 0DBL0ZZ 0DTL4ZZ 4582 0DBL3ZZ 0DTL7ZZ 4583 0DBL4ZZ 0DTM0ZZ 0DBL7ZZ 0DTM4ZZ 0DBM0ZZ 0DTM7ZZ 0DBM3ZZ 0DTN0ZZ 0DBM4ZZ 0DTN4ZZ 0DBM7ZZ 0DTN7ZZ
Table 2: Patient characteristics among beneficiaries excluded from primary analysis.
Beneficiaries visiting a CAH that is Total
Participating in a hospital network
Not participating in a
hospital network P Value
No. of patients N=5,810 N=3,500 N=2,310
Demographic characteristics
Age, mean (SD) 75.1 (7.1) 75.0 (7.1) 75.2 (7.3) 0.36
Men 2,714 (46.7%) 1,608 (45.9%) 1,106 (47.9%) 0.15
Race (Non-missing %)
White 5,304 (95.4%) 3,166 (94.3%) 2,138 (97.0%) <0.001
Black 111 (2.0%) 88 (2.6%) 23 (1.0%) <0.001
Asian 13 (0.2%) 10 (0.3%) 3 (0.1%) 0.22
Hispanic 51 (0.9%) 41 (1.2%) 10 (0.5%) 0.003
Native American 43 (0.8%) 25 (0.7%) 18 (0.8%) 0.76
Other 39 (0.7%) 28 (0.8%) 11 (0.5%) 0.14
Missing (Total %) 249 (4.7%) 142 (4.1%) 107 (4.6%) -
Comorbidities
Hypertension 3,747 (64.5%) 2,311 (66.0%) 1,436 (62.2%) 0.003
Fluid and electrolyte disorders 1,507 (25.9%) 949 (27.1%) 558 (24.2%) 0.012
Diabetes 1,405 (24.2%) 898 (25.7%) 507 (21.9%) 0.001
Chronic pulmonary disease 1,085 (18.7%) 686 (19.6%) 399 (17.3%) 0.026
Hypothyroidism 855 (14.7%) 543 (15.5%) 312 (13.5%) 0.034
Deficiency Anemias 864 (14.9%) 558 (15.9%) 306 (13.2%) 0.005
Obesity 742 (12.8%) 524 (15.0%) 218 (9.4%) <0.001
Renal failure 558 (9.6%) 369 (10.5%) 189 (8.2%) 0.003
Depression 518 (8.9%) 352 (10.1%) 166 (7.2%) <0.001
Congestive heart failure 453 (7.8%) 284 (8.1%) 169 (7.3%) 0.27
Other neurological disorders 385 (6.6%) 242 (6.9%) 143 (6.2%) 0.28
Weight loss 297 (5.1%) 211 (6.0%) 86 (3.7%) <0.001
Metastatic cancer 267 (4.6%) 160 (4.6%) 107 (4.6%) 0.91
Peripheral vascular disease 288 (5.0%) 193 (5.5%) 95 (4.1%) 0.016
Valvular disease 248 (4.3%) 171 (4.9%) 77 (3.3%) 0.004
Liver disease 222 (3.8%) 150 (4.3%) 72 (3.1%) 0.023
Solid tumor 180 (3.1%) 122 (3.5%) 58 (2.5%) 0.036
Rheumatoid arthritis 175 (3.0%) 103 (2.9%) 72 (3.1%) 0.70
Coagulopthy 161 (2.8%) 110 (3.1%) 51 (2.2%) 0.034
Psychoses 85 (1.5%) 57 (1.6%) 28 (1.2%) 0.20
Elixhauser comorbidities
0 703 (12.1%) 385 (11.0%) 318 (13.8%) 0.002
1 1,207 (20.8%) 674 (19.3%) 533 (23.1%) <0.001
≥2 3,900 (67.1%) 2,441 (69.7%) 1,459 (63.2%) <0.001
Discharge location
Home 4,458 (76.7%) 2,659 (76.0%) 1,799 (77.9%) 0.092
Skilled Nursing Facility,
rehabilitation 573 (9.9%) 408 (11.7%) 165 (7.1%) <0.001
Transferred 282 (4.9%) 173 (4.9%) 109 (4.7%) 0.70
Other 475 (8.2%) 246 (7.0%) 229 (9.9%) <0.001
Hospice 22 (0.4%) 14 (0.4%) 8 (0.3%) 0.74
Admission Type
Emergency 1,830 (31.5%) 1,171 (33.5%) 659 (28.5%) <0.001
Urgent 1,351 (23.3%) 745 (21.3%) 606 (26.2%) <0.001
Elective 2,629 (45.2%) 1,584 (45.3%) 1,045 (45.2%) 0.99
Type of operation
Appendectomy 691 (11.9%) 396 (11.3%) 295 (12.8%) 0.093
Cholecystectomy 2,000 (34.4%) 1,160 (33.1%) 840 (36.4%) 0.011
Colectomy 2,239 (38.5%) 1,354 (38.7%) 885 (38.3%) 0.77
Hernia Repair 880 (15.1%) 590 (16.9%) 290 (12.6%) <0.001
Travel distance in miles, median (IQR)
12.0 (0.0-
22.7) 12.1 (0.0-22.4) 11.0 (0.0-23.5) 0.13
Travel time in minutes, median (IQR)
18.0 (0.0-
31.0) 18.0 (0.0-30.0) 16.0 (0.0-31.0) 0.021
Travel time in minutes (Non- missing %)
<30 4,036 (73.5%) 2,521 (74.0%) 1,515 (72.7%) 0.26
30-60 1,024 (18.7%) 610 (17.9%) 414 (19.9%) 0.073
>60 430 (7.8%) 274 (8.0%) 156 (7.5%) 0.45
Missing (Total %) 320 (5.5%) 95 (2.7%) 225 (9.7%) -
Data: Medicare, Common Procedures 2014-2018, Critical Access Hospitals, Missing (race, cost, or travel distance)
CAH – critical access hospital
Table 3 – Summary of missing data for surgery relevant resources and capabilities at CAHs.
CAH - critical access hospital, CT – computed tomography, ICU – intensive care unit CAHs with missing data
Beneficiaries with missing data
All CAHs with missin g data
CAHs participatin g in a hospital network
CAHs not participatin g in a hospital network ICU capability 712/16,128
(4.4%)
47/755 (6.2%)
17/393 (4.3%)
30/362 (8.3%) Trauma center designation 712/16,128
(4.4%)
47/755 (6.2%)
17/393 (4.3%)
30/362 (8.3%) CT scanner availability 712/16,128
(4.4%)
47/755 (6.2%)
17/393 (4.3%)
30/362 (8.3%) Ultrasound availability 712/16,128
(4.4%)
47/755 (6.2%)
17/393 (4.3%)
30/362 (8.3%) Number of operating
rooms
1,210/16,12 8 (7.5%)
61/755 (8.1%)
23/393 (5.9%)
38/362
(10.5%)
Inpatient surgical volume 0/16,128 0/755 0/405 0/350
Table 4 – summary of differences in mean Medicare payments for total episodes of pay with combinations of raw versus price-standardized and risk-adjusted versus non-risk-adjusted payments.
Mean Total Payment (Median for non-risk-adjusted)
CAHs not participating in hospital networks
CAHs
participating in hospital networks
Difference in Mean Payment (Median) Raw Payment, Non-risk-adjusted 16848 (17168) 17086 (17026) 238 (-142)
Standardized Payment, Non-risk-
adjusted 17890 (17502) 17641 (17241) -249 (-261)
Standardized Payment, Risk-Adjusted 23878 22918 -960
Cohorts: Medicare, 2014-2018, Appendectomy, Cholecystectomy, Colectomy, Hernia Repair Risk-Adjustment Model: Sex, age, year, cohort, admission type (emergent, urgent, elective), comorbidities
Comorbidities: Hypertension, fluid and electrolyte disorders, diabetes, chronic lung disease, anemia, hypothyroidism, congestive heart failure, metastatic cancer, obesity, depression, renal failure, neuropathy, weight loss
Mean total payment for non-risk-adjusted payments is log-transformed for analysis and then back- transformed for reporting