567 HSAs in the main analysis
After excluding HSAs crossing borders (n = 55), 512 HSAs were included in the sensitivity analysis
State # of operations # of HSAs with
≥11 operations
NY 65736 121
FL 79533 104
GA 19399 92
KY 10864 64
NC 23245 86
MS 5904 45
Total 204681 512
After excluding border HSAs
State # of operations # of HSAs with
≥11 operations
NY 67570 131
FL 85876 112
GA 23257 107
KY 11964 72
NC 24217 94
MS 3675 51
Before excluding border HSAs,
same with the text in the results section
• After excluding HSAs crossing state borders, age-standardized rates of operations and mortality rates are still significantly differed by HSA and by state (p all < 0.001).
• The rates are basically the same before and after excluding border HSAs (see the updated table 2).
Updated Table 2: Age-standardized rates of EGS operations per 10,000 in the population and deaths per 1,000 operations, by geographic region and operation type after excluding border HSAs.
Geographic Region Operation Ratea Mortality rate
All 6 States Combined 22.5 7.4
Northeastern Statesb 22.8 7.2
New Yorkc 22.8 7.2
Southeastern Statesb 22.3 7.5
Floridac 29.8 6.0
Georgiac 17.4 8.5
Kentuckyc 19.0 8.8
North Carolinac 17.0 9.1
Mississippic 10.3 5.8
Age-standardized operation rates Age-standardized mortality rates Adding 0.025 Adding 0.05 Adding 0.025 Adding 0.05
Variance Variance Variance Variance
HSA 0.22 (6%) 0.19 (6%) 0.66 (8%) 0.51 (7%)
State 0.42 (11%) 0.38 (12%) 0.44 (5%) 0.33 (5%) Residual
3.12 (83%)
2.57 (82%)
7.56 (87%)
6.05 (88%) sum 3.76 (100%) 3.14 (100%) 8.66 (100%) 6.89 (100%) After excluding border HSAs
Supplementary Table A:Variances explained by state and HSA under different scenarios of rates adjustment,
calculated using linear random effects models. In the models, states and HSAs were included as random effects. The distributions of rates were heavily skewed and included many zeros, so the rates were log transformed and 0.05 was added. We conducted sensitivity analyses by alternatively adding 0.025 to the rates, respectively. HSA, health service area:
Updated Figure 2 (excluding border HSAs):Variation profile of normalized operation rates by state. Each dot represents the normalized operation rate for one HSA. Normalized rate is
calculated by dividing the age-standardized operation rate for a given HSA by the overall mean operation rate of the entire
study population for all six states. Only HSAs with ≥11 total EGS operations were included. The y-axis is the range of normalized ratio values. NY, New York; FL, Florida; GA, Georgia; KY,
Kentucky; NC, North Carolina; MS, Mississippi.
Updated Figure 4 (excluding border HSAs): Variation profile of normalized EGS mortality rates by state. Each dot represents the normalized mortality rate for one HSA.
Normalized rate is calculated by dividing the age-
standardized mortality rate for a given HSA by the overall mean mortality rate of the entire study population for all six states. Only HSAs with > 11 total EGS operations were included. The y-axis is the range of normalized ratio
values. NY, New York; FL, Florida; GA, Georgia; KY, Kentucky; NC, North Carolina; MS, Mississippi.