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. Author manuscript; available in PMC: 2011 Jun 23.
Published in final edited form as: Med Care. 2009 Sep;47(9):968–978. doi: 10.1097/MLR.0b013e31819c9415

APPENDIX TABLE 1.

Estimation Results From Alternative Models on Trauma Center Closures Between 1990 to 2005

Model 2 (Include
Early Adopter
Indicator)
Model 3 (Cox
Proportional
Hazard)
Model 4 (Exclude
Profit Margin)
Model 5
(Standard SE)
Hazard
Ratio
P Hazard
Ratio
P Hazard
Ratio
P Hazard
Ratio
P
Financial pressure measures
 Profit margin
  Hospital with (−5, 5)% margin 1.000 1.000 1.000
  Hospital with < − 5% profit margin 1.295* 0.07 1.391 0.01 1.384 0.00
  Hospital with >5% profit margin 0.971 0.85 1.048 0.73 1.010 0.88
 Medicare payment generosity
  Receive average reimbursement 1.000 1.000 1.000
  Received less generous Medicare reimbursement than average 0.984 0.92 1.021 0.89 1.002 0.99 1.024 0.72
  Received more generous Medicare reimbursement than average 0.555 0.01 0.629 0.02 0.614 0.03 0.578 0.00
 Medicaid payment generosity
  Hospitals in states with average Medicaid physician payment 1.000 1.000 1.000
  Hospitals in states with below average Medicaid physician payment 1.439* 0.05 1.127 0.50 1.231 0.25 1.237 0.00
  Hospitals in states with above average Medicaid physician payment 0.998 0.99 0.935 0.64 0.928 0.62 0.939 0.33
 HMO penetration level
  Low HMO markets 1.000 1.000 1.000
  Medium HMO markets 1.581 0.01 1.618 0.00 1.622 0.00 1.628 0.00
  High HMO markets 1.953 0.00 2.012 0.00 2.064 0.00 2.059 0.00
County population characteristics
 Minority population
  Low share (lower 1/3) 1.000 1.000 1.000
  Medium share 1.176 0.34 1.226 0.19 1.218 0.24 1.213 0.01
  High share 1.587 0.01 1.694 0.00 1.693 0.01 1.693 0.00
 Population under poverty line
  Low share (lower 1/3) 1.000 1.000 1.000
  Medium share 1.058 0.75 1.078 0.63 1.059 0.74 1.048 0.51
  High share 1.339 0.20 1.303 0.20 1.352 0.18 1.352 0.00
 Elderly population
  Low share (lower 1/3) 1.000 1.000 1.000
  Medium share 1.134 0.43 1.124 0.43 1.129 0.44 1.122* 0.08
  High share 1.321 0.11 1.321* 0.08 1.305 0.13 1.278 0.00
 Uninsured population in 2000
  15% or lower 1.000 1.000 1.000
  Greater than 15% 0.933 0.68 0.908 0.55 0.902 0.54 0.908 0.18
 Other population characteristics
  Population (log transformed) 1.015 0.84 1.028 0.70 1.038 0.61 1.034 0.29
  Cost of living (log transformed) 1.199 0.78 0.696 0.53 0.616 0.43 0.656 0.10
Hospital characteristics
  For-profit hospital 1.846 0.00 1.895 0.00 1.944 0.00 1.975 0.00
  Government hospital 0.847 0.42 0.876 0.50 0.892 0.57 0.856* 0.07
  Teaching hospital 0.502 0.00 0.417 0.00 0.438 0.00 0.444 0.00
  Member of a system 1.261* 0.09 1.250* 0.07 1.271* 0.07 1.276 0.00
  Case-mix index (log transformed) 0.132 0.00 0.114 0.00 0.097 0.00 0.108 0.00
  Total visits to ED (log transformed) 0.846 0.00 0.856 0.00 0.844 0.00 0.848 0.00
Hospital market characteristics
 Presence of another trauma center within 15-mile radius 0.857 0.29 0.807 0.11 0.849 0.26 0.833 0.00
   Share of Medicaid discharges twice as much as the average competitor within 15-mile radius 0.810 0.37 0.854 0.44 0.882 0.59 0.840* 0.09
   Competitive hospital market (hospital Herfindahl index <0.25) 0.765 0.13 0.734* 0.06 0.720* 0.06 0.703 0.00
 Percent for-profit hospitals within 15-mile radius 1.055 0.90 1.103 0.79 1.066 0.88 1.092 0.59
 Percent government hospitals within 15-mile radius 1.634 0.31 1.512 0.37 1.594 0.33 1.561 0.03
Early adopter indicator
 = 1 if provide trauma center service since 1990 0.485 0.00
Observations 9555 9555 9555 9555
*

Significant at 1%;

significant at 10%;

significant at 5%.

Census region and year indicators are included.