Background
Methods
Data source
Patient selection
Study measures
Data analysis
Results
Population characteristics
Imaging utilization rates
2000 | 2001 | 2002 | 2003 | 2004 | 2005 | 2006 | 2007 | 2008 | 2009 | 2000-2009* | |
---|---|---|---|---|---|---|---|---|---|---|---|
Unweighted N | 23,839 | 32,122 | 37,418 | 32,681 | 32,737 | 32,320 | 32,577 | 29,370 | 31,262 | 34,920 | 319,246 |
Imaging utilization rate | 64.3 | 85.9 | 92.3 | 107.2 | 109.6 | 112.6 | 107.4 | 116.8 | 119.6 | 109.1 | 102.9 |
Age | |||||||||||
<18 | 14.3 | 20.4 | 24.2 | 29.3 | 20.3 | 27.1 | 21.4 | 24.1 | 27.4 | 26.8 | 23.6 |
18-44 | 44.5 | 74.7 | 67.1 | 62.9 | 87.0 | 81.1 | 80.5 | 72.7 | 73.4 | 74.8 | 71.9 |
45-64 | 97.5 | 121.9 | 141.3 | 186.0 | 161.5 | 170.6 | 164.1 | 171.8 | 185.8 | 172.5 | 159.1 |
65+ | 160.9 | 182.6 | 219.3 | 244.0 | 253.8 | 261.4 | 241.4 | 309.3 | 282.8 | 234.3 | 240.4 |
Gender | |||||||||||
Male | 54.7 | 78.1 | 80.3 | 92.2 | 93.5 | 98.6 | 92.6 | 106.3 | 98.8 | 99.4 | 89.8 |
Female | 73.5 | 93.3 | 103.8 | 121.6 | 125.0 | 126.1 | 121.7 | 126.9 | 139.6 | 118.6 | 115.4 |
Race/ethnicity | |||||||||||
White | 73.5 | 95.9 | 108.5 | 126.3 | 128.6 | 135.3 | 127.3 | 137.9 | 146.6 | 133.7 | 121.4 |
Non-white | 41.7 | 62.9 | 58.3 | 67.3 | 71.2 | 67.8 | 69.1 | 76.7 | 68.8 | 63.7 | 65.3 |
Census region | |||||||||||
Northeast | 72.3 | 109.2 | 97.1 | 108.7 | 129.3 | 120.7 | 128.8 | 140.1 | 135.3 | 112.7 | 115.6 |
South | 64.6 | 81.5 | 93.1 | 114.6 | 112.0 | 116.4 | 109.9 | 111.2 | 102.2 | 110.3 | 102.1 |
Midwest | 57.3 | 88.1 | 96.2 | 95.0 | 109.7 | 119.9 | 105.2 | 118.6 | 131.4 | 108.7 | 103.2 |
West | 56.2 | 66.5 | 83.0 | 102.2 | 87.7 | 91.8 | 86.5 | 101.6 | 117.3 | 104.6 | 90.3 |
Rural/urban residence | |||||||||||
MSA | 61.0 | 87.1 | 89.0 | 106.3 | 106.7 | 111.9 | 105.3 | 116.0 | 118.7 | 110.2 | 101.8 |
Non-MSA | 68.9 | 74.5 | 106.4 | 105.8 | 120.6 | 113.7 | 114.9 | 114.7 | 114.5 | 102.7 | 103.4 |
Payer type | |||||||||||
Medicare | 131.4 | 195.2 | 187.0 | 238.7 | 241.3 | 255.6 | 261.8 | 276.0 | 303.8 | 223.1 | 234.2 |
Medicaid | 32.2 | 62.1 | 65.8 | 60.3 | 58.3 | 78.9 | 67.8 | 58.1 | 69.1 | 62.4 | 62.5 |
Private | 52.8 | 78.0 | 84.0 | 91.2 | 96.7 | 97.8 | 95.1 | 98.7 | 105.4 | 96.9 | 89.6 |
Medicare + Medicaid | 183.6 | 124.4 | 248.5 | 194.9 | 269.5 | 227.5 | 172.0 | 240.9 | 219.0 | 357.5 | 226.8 |
Medicare + Private | 180.5 | 188.0 | 237.9 | 253.2 | 265.0 | 295.9 | 250.6 | 364.0 | 300.6 | 253.3 | 257.8 |
Other public** | 243.0 | 235.1 | 78.4 | 100.5 | 98.2 | 122.7 | 104.7 | 133.1 | 123.4 | 149.3 | 131.4 |
Uninsured | 32.9 | 37.2 | 30.8 | 74.3 | 61.1 | 54.8 | 58.1 | 60.6 | 48.9 | 56.2 | 51.8 |
Other | 91.2 | 96.8 | 134.4 | 175.1 | 165.5 | 160.2 | 165.1 | 141.0 | 205.9 | 164.3 | 152.5 |
Managed care status | |||||||||||
Managed care | 59.0 | 80.2 | 86.4 | 97.3 | 103.1 | 107.9 | 108.3 | 118.6 | 113.4 | 114.9 | 99.9 |
Non-managed care | 69.1 | 93.8 | 100.7 | 121.0 | 118.5 | 119.0 | 106.2 | 114.4 | 127.2 | 102.0 | 106.8 |
Predictors of imaging utilization
Covariate | OR estimate | 95% confidence limits | |
---|---|---|---|
Managed care vs. non-managed care |
1.066
|
1.015
|
1.120
|
Payer type (vs. uninsured) | |||
Medicare |
2.749
|
2.437
|
3.102
|
Medicaid |
1.987
|
1.799
|
2.195
|
Private |
1.619
|
1.505
|
1.741
|
Medicare + Medicaid |
3.076
|
2.708
|
3.493
|
Medicare + Private |
3.027
|
2.678
|
3.422
|
Other public* |
2.194
|
1.818
|
2.647
|
Other |
2.375
|
2.153
|
2.620
|
Year (vs. 2005) | |||
2000 |
0.579
|
0.523
|
0.642
|
2001 |
0.737
|
0.678
|
0.801
|
2002 |
0.865
|
0.798
|
0.937
|
2003 |
0.890
|
0.828
|
0.956
|
2004 | 0.950 | 0.882 | 1.025 |
2006 | 0.987 | 0.915 | 1.064 |
2007 | 1.043 | 0.971 | 1.120 |
2008 | 1.013 | 0.936 | 1.097 |
2009 | 0.969 | 0.894 | 1.051 |
Age (vs. <18 years) | |||
18-44 years |
2.954
|
2.746
|
3.178
|
45-64 years |
5.514
|
5.126
|
5.931
|
65+ years |
5.016
|
4.469
|
5.630
|
Male (vs. female) |
0.820
|
0.790
|
0.850
|
White (vs. non-white) |
1.598
|
1.526
|
1.674
|
Census region (vs. Northeast) | |||
South | 0.985 | 0.924 | 1.050 |
Midwest | 0.970 | 0.904 | 1.041 |
West |
0.843
|
0.780
|
0.911
|
Urban (vs. rural) |
1.056
|
1.000
|
1.114
|
Discussion
Summary & implications
Comparison to literature
Limitations
Conclusions
Appendix: supplementary regressions
Covariate | Parameter estimate |
P-Value |
---|---|---|
Managed care vs. non-managed care |
0.068
|
0.007
|
Payer type (vs. uninsured) | ||
Medicare |
1.010
|
<.0001
|
Medicaid |
0.685
|
<.0001
|
Private |
0.480
|
<.0001
|
Medicare + Medicaid |
1.122
|
<.0001
|
Medicare + Private |
1.106
|
<.0001
|
Other public* |
0.787
|
<.0001
|
Other |
0.865
|
<.0001
|
Year** | ||
Year A |
0.114
|
<.0001
|
Year B |
−0.115
|
<.0001
|
Age (vs. <18 years) | ||
18-44 years |
1.083
|
<.0001
|
45-64 years |
1.708
|
<.0001
|
65+ years |
1.614
|
<.0001
|
Male (vs. female) |
−0.199
|
<.0001
|
White (vs. non-white) |
0.468
|
<.0001
|
Census region (vs. Northeast) | ||
South | −0.015 | 0.647 |
Midwest | −0.030 | 0.400 |
West |
−0.171
|
<.0001
|
Urban (vs. rural) | 0.053 | 0.054 |
Covariate | Parameter estimate |
P-Value |
---|---|---|
Managed care vs. non-managed care |
0.0813
|
0.0075
|
Payer type (vs. uninsured) | ||
Medicare |
1.0348
|
<.0001
|
Medicaid |
0.6906
|
<.0001
|
Private |
0.4543
|
<.0001
|
Medicare + Medicaid |
1.0667
|
<.0001
|
Medicare + Private |
1.1154
|
<.0001
|
Other public* |
0.7998
|
<.0001
|
Other |
0.8215
|
<.0001
|
Year** | −0.00434 | 0.6466 |
Age (vs. <18 years) | ||
18-44 years |
1.0995
|
<.0001
|
45-64 years |
1.7388
|
<.0001
|
65+ years |
1.6151
|
<.0001
|
Male (vs. female) |
−0.2048
|
<.0001
|
White (vs. non-white) |
0.4462
|
<.0001
|
Census region (vs. Northeast) | ||
South | −0.0119 | 0.7565 |
Midwest | −0.0421 | 0.3601 |
West |
−0.1758
|
0.0002
|
Urban (vs. rural) |
0.089
|
0.032
|
Covariate | Parameter estimate |
P-Value |
---|---|---|
Managed care vs. non-managed care |
0.044
|
0.237
|
Payer type (vs. uninsured) | ||
Medicare |
0.966
|
<.0001
|
Medicaid |
0.681
|
<.0001
|
Private |
0.518
|
<.0001
|
Medicare + Medicaid |
1.194
|
<.0001
|
Medicare + Private |
1.093
|
<.0001
|
Other public* |
0.761
|
<.0001
|
Other |
0.924
|
<.0001
|
Year** |
0.113
|
<.0001
|
Age (vs. <18 years) | ||
18-44 years |
1.064
|
<.0001
|
45-64 years |
1.669
|
<.0001
|
65+ years |
1.616
|
<.0001
|
Male (vs. female) |
−0.191
|
<.0001
|
White (vs. non-white) |
0.500
|
<.0001
|
Census region (vs. Northeast) | ||
South | −0.019 | 0.691 |
Midwest | −0.015 | 0.752 |
West |
−0.166
|
0.003
|
Urban (vs. rural) | 0.014 | 0.661 |