The performance of administrative and self-reported measures for risk adjustment of veterans affairs expenditures

Health Services Research, June, 2005 by Matthew L. Maciejewski, Chuan-Fen Liu, Ann Derleth, Mary McDonell, Steve Anderson, Stephan D. Fihn

Table 1: Descriptive Statistics of Sample of Veterans Regularly
Using Primary Care

                                    Mean (SD)      Minimum    Maximum

Prediction year total cost        5,739 (17,876)     0       589,018.60
Prediction year outpatient cost   2,428 (3015)       0        68,116.39
Prediction year inpatient cost    3,312 (17,135)     0       589,018.60
Age                               64.46 (11.34)     21            97
Male (%)                          98.48              --          --
PCS                               33.32 (11.61)      6            73.54
MCS                               45.65 (13.17)      2.35         75.80
SIC                                6.40 (2.98)       0            23
Charlson score                     0.24 (0.92)       0            14
ACG                                1.07 (0.79)       0.05          3.30
DCG                                1.28 (l.04)       0            10.58
CDPS                               1.93 (1.37)       0.06         13.86
RxRisk                             1.27 (0.83)       0            11.46
Base year total cost              4,383 (8825)       0       180,490.4
Base year outpatient cost         2,308 (2772)       0        72,319.38
Base year inpatient cost          2,076 (7750)       0       176,306.4
Sample size                                        14,449

Note: Standard deviation in parentheses.

PCS, Physical Component Scores; MCS, Mental Component Score; SIC,
Seattle Index of Comorbidity; ACG, Adjusted Clinical Group; DCG,
Diagnostic Cost Group; CDPS, Chronic Illness and Disability
Payment System.

Table 2: Correlation Matrix of Eight Risk Adjustment Measures

                          MCS       PCS    RxRisk   SI C

PCS                       0.18
RxRisk                   -0.21     -0.36
SIC                      -0.03     -0.29    0.34
Charlson                 -0.06     -0.12    0.35    0.20
ACG                      -0.17     -0.25    0.50    0.22
CDPS                     -0.12     -0.21    0.48    0.25
DCG                      -0.16     -0.26    0.58    0.29
Prior total cost         -0.11     -0.14    0.39    0.12
Prior outpatient cost    -0.15     -0.15    0.39    0.09

                        Charlson    ACG     CDPS    DCG

PCS
RxRisk
SIC
Charlson
ACG                       0.36
CDPS                      0.41     0.60
DCG                       0.55     0.73     0.72
Prior total cost          0.52     0.50     0.42    0.58
Prior outpatient cost     0.26     0.54     0.44    0.55

                         Prior     Total    Cost

PCS
RxRisk
SIC
Charlson
ACG
CDPS
DCG
Prior total cost
Prior outpatient cost              0.52

PCS, Physical Component Scores; MCS, Mental Component Score; SIC,
Seattle Index of Comorbidity; ACG, Adjusted Clinical Group; DCG,
Diagnostic Cost Group; CDPS, Chronic Illness and Disability
Payment System.

Table 3: Alternative Risk Adjustment Measures in Prospective
Cost Models

                                           Adjusted [R.sup.2]

                                     Total   Inpatient   Outpatient
                                     Cost      Cost         Cost

Age and gender alone (%)             0.22      0.24         0.12
Prior year cost                      4.79      1.95        41.93
Self-report measures
  PCS MCS (SF-36 summaries)          1.79      1.04         3.96
  SIC                                1.36      0.94         1.86
Administrative data-based measures
  Charlson (%)                       3.56      2.40         4.63
  ACG                                5.14      2.22        18.00
  DCG-HCC                            7.16      3.43        20.63
  CDPS                               3.78      1.59        14.40
  RxRisk                             4.73      2.31        13.51
Combined models
  DCG, Prior cost                    7.74      3.64        43.20
  DCG, RxRisk                        7.74      3.69        22.38
  DCG, RxRisk, prior cost            8.23      3.88        43.82
  DCG, RxRisk, prior cost, SF        8.33      3.95        43.90
Sample size                                      14,449

Note: All self-report and diagnosis-based measures include age
and gender.

PCS, Physical Component Scores; MCS, Mental Component Score; SIC,
Seattle Index of Comorbidity; HCC, Hierarchical Cost Categories;
ACG, Adjusted Clinical Group; DCG, Diagnostic Cost Group; CDPS,
Chronic Illness and Disability Payment System.

Table 4: Predictive Ratios in Prospective Total Cost Models

                                            Second
                          Lowest Cost     Lowest Cost    Middle Cost
                           Quintile        Quintile       Quintile

Age and gender alone         26.33           5.49           2.87
Prior cost                   22.05           4.64           2.67
Self-report measures
  PCS MCS (SF-36             23.87           4.96           2.84
    summaries
  SIC                        24.96           5.21           2.84
Administrative
  data-based measures
    Charlson                 24.38           4.99           2.73
    ACG                      17.16           4.10           2.76
    DCG-HCC                  17.13           3.90           2.66
    CDPS                     20.05           4.65           2.82
    RxRisk                   19.08           4.44           2.80
Combined models
    DCG, prior cost          17.13           3.85           2.61
    DCG, RxRisk              15.80           3.76           2.67
    DCG, RxRisk,             15.90           3.73           2.62
      prior cost
    DCG, RxRisk, prior       15.73           3.65           2.62
      cost, SF
Sample size                                                14,449
                            Second
                            Highest         Highest
                         Cost Quintile   Cost Quintile

Age and gender alone         1.45            0.23
Prior cost                   1.55            0.31
Self-report measures
  PCS MCS (SF-36             1.56            0.26
    summaries
  SIC                        1.50            0.25
Administrative
  data-based measures
    Charlson                 1.48            0.29
    ACG                      1.70            0.33
    DCG-HCC                  1.72            0.36
    CDPS                     1.64            0.29
    RxRisk                   1.68            0.31
Combined models
    DCG, prior cost          1.71            0.37
    DCG, RxRisk              1.77            0.37
    DCG, RxRisk,             1.75            0.38
      prior cost
    DCG, RxRisk, prior       1.77            0.38
      cost, SF
Sample size

PCS, Physical Component Scores; MCS, Mental Component Score; SIC,
Seattle Index of Comorbidity; HCC, Hierarchical Cost Categories;
ACG, Adjusted Clinical Group; DCG, Diagnostic Cost Group; CDPS,
Chronic Illness and Disability Payment System.