Background
Methods
Study population
Volume categories and co-morbidity adjustment
Statistical analysis
Low volume | Intermediate volume | High volume | ||||||
---|---|---|---|---|---|---|---|---|
N | 963 | 63.9 | 370 | 24.5 | 174 | 11.6 | ||
Baseline Characteristic | N/mean | %/stdev | p-value* | N/mean | %/stdev | p-value* | N/mean | %/stdev |
Age (years) | 59.1 | 14.8 | 0.196 | 59.6 | 14.5 | 0.142 | 57.6 | 15.6 |
Male gender | 651 | 67.6 | 0.926 | 253 | 68.4 | 0.791 | 117 | 67.2 |
Primary payer: Medicare | 356 | 37 | 0.037 | 137 | 37 | 0.058 | 50 | 28.7 |
Primary payer: Medicaid | 80 | 8.3 | 0.003 | 23 | 6.2 | <0.001 | 27 | 15.5 |
Primary payer: Private insurance | 391 | 40.6 | 0.185 | 157 | 42.4 | 0.437 | 80 | 46 |
Comorbidities | ||||||||
APR-DRG severity score | 3.38 | 0.66 | 0.195 | 3.46 | 0.63 | 0.007 | 3.31 | 0.61 |
Hypertension | 585 | 60.8 | 0.853 | 218 | 59 | 0.568 | 107 | 61.5 |
Peripheral vascular disorder | 183 | 19 | 0.868 | 82 | 22.2 | 0.486 | 34 | 19.5 |
Obesity | 82 | 8.5 | 0.218 | 25 | 6.8 | 0.654 | 10 | 5.8 |
Renal failure | 81 | 8.4 | 0.046 | 38 | 10.3 | 0.014 | 7 | 4.0 |
Diabetes Mellitus | 76 | 7.9 | 0.849 | 25 | 6.8 | 0.760 | 13 | 7.5 |
Paralysis | 55 | 5.7 | 0.123 | 16 | 4.3 | 0.413 | 5 | 2.9 |
Hx alcohol abuse | 50 | 5.2 | 0.991 | 19 | 5.1 | 0.985 | 9 | 5.2 |
Hx drug abuse | 39 | 4.1 | 0.708 | 17 | 5 | 0.535 | 6 | 3.5 |
Results
Baseline demographics
Low volume | Intermediate volume | High volume | ||||||
---|---|---|---|---|---|---|---|---|
N = 963 | N = 370 | N = 174 | ||||||
Admission type | Mean | St.dev | p-value** | Mean | St.dev | p-value** | Mean | St.dev |
APR-DRG severity of illness score | ||||||||
Direct Admission | 3.39 | 0.64 | 0.408 | 3.44 | 0.67 | 0.186 | 3.32 | 0.64 |
Transfer Admission | 3.35 | 0.59 | 0.322 | 3.38 | 0.60 | 0.244 | 3.24 | 0.56 |
Other | 3.37 | 0.72 | 0.890 | 3.57 | 0.57 | 0.031 | 3.36 | 0.64 |
Total | 3.38 | 0.66 | 0.195 | 3.46 | 0.63 | 0.001 | 3.31 | 0.61 |
APR-DRG risk of mortality score | ||||||||
Direct Admission | 3.22 | 0.70 | 0.126 | 3.25 | 0.72 | 0.099 | 3.08 | 0.85 |
Transfer Admission | 3.19 | 0.67 | 0.192 | 3.14 | 0.56 | 0.321 | 3.02 | 0.72 |
Other | 3.29 | 0.73 | 0.242 | 3.43 | 0.64 | 0.015 | 3.17 | 0.65 |
Total | 3.23 | 0.75 | 0.015 | 3.28 | 0.68 | 0.004 | 3.09 | 0.75 |
Admission types
Mortality
Low volume | Intermediate volume | High volume | ||||||
---|---|---|---|---|---|---|---|---|
N = 963 | N = 369 | N = 174 | ||||||
Admission type | Death/no of patients in group | % | p-value** | Death/no of patients in group | % | p-value** | Death/no of patients in group | % |
Direct Admission | 154/641 | 24.0 | 0.013 | 44/206 | 21.4 | 0.051 | 7/66 | 10.6 |
Transfer Admission | 16/68 | 23.5 | 0.064 | 8/64 | 12.7 | 0.683 | 5/49 | 10.2 |
Other | 60/254 | 23.6 | 0.268 | 24/100 | 24.0 | 0.295 | 10/59 | 17.0 |
Total | 230/963 | 23.9 | 0.001 | 76/369* | 20.6 | 0.025 | 22/174 | 12.6 |
Variable | Odds ratio | Standard error | 95 % confidence interval | p-value |
---|---|---|---|---|
High volume vs. low volume centers | ||||
Low volume | 2.06 | 0.52 | 1.25 – 3.38 | 0.004 |
Direct admission | 1.02 | 0.17 | 0.73 – 1.43 | 0.907 |
Transfer admission | 0.99 | 0.29 | 0.56 – 1.75 | 0.964 |
Other admission | 1.00 | 0.00 | N/A | 1.000 |
Age | 1.02 | 0.01 | 1.01 – 1.03 | 0.001 |
APRDRG risk of mortality | 2.20 | 0.36 | 1.60 – 3.03 | <0.001 |
High volume vs. intermediate volume centers | ||||
Intermediate volume | 1.45 | 0.41 | 0.83 – 2.54 | 0.195 |
Direct admission | 0.90 | 0.24 | 0.53 – 1.52 | 0.692 |
Transfer admission | 0.58 | 0.22 | 0.27 – 1.22 | 0.152 |
Other admission | 1.00 | 0.00 | N/A | 1.000 |
Age | 1.03 | 0.01 | 1.01 – 1.05 | 0.005 |
APRDRG risk of mortality | 3.61 | 1.09 | 2.00 – 6.51 | <0.001 |