The Charlson Comorbidity Index - Text Mining Techniques for Healthcare Provider Quality Determination - page 185

level one. However, Charlson Index 3 is scattered across all values of the new index with a peak of just
23%. Moreover, the Charlson Index of 12 has most of its values at a new index value of 4 or below.

valIdatIon

We want to validate these indices by using another dataset. In this case, we use the Medical Expen-
diture Panel Survey (MEPS). We use the inpatient dataset to look at the costs involved in treatment.
Unfortunately, the MEPS truncates the ICD9 codes to 3 digits. Therefore, it is not possible to use the
MEPS datasets to compute the Charlson Index. However, there is a modification of the Charlson Index
developed by D'Hoore that only uses 3 digit ICD9 codes. Therefore, we will consider this adaptation
after we validate the New Index. (Schneeweiss & Maclure, 2000)
Since the New Index uses the 3 digit truncation, we can compute it on MEPS data. Table 24 shows
the results. Since the MEPS inpatient dataset limits the number of ICD9 diagnosis codes to 4, the highest
the index can go is to a value of 4. It also shows that there will be diagnosis codes that are part of the
New Index that will be omitted from the computation just for lack of space. In the table, mdtotal=total
payment to physician, fcpayment=total payment to hospital. Total charges represent the total charged for
treatment; totalexpenditure is the total reimbursed to the providers. The value NUMNIGHTX represents
the length of stay.

Table 24. New index for MEPS inpatient data for 2003-2005

newindex N Obs Variable Mean Std Dev Minimum Maximum N

0 8252 mdtotal

fcpayment
totalcharge
totalexpenditure
NUMNIGHX

3565.89
8381.05
25542.01
9729.83
5.4634028

5910.45
17536.86
50220.27
18437.73
10.6935358

0
0
10.0000000
0
0

198416.00
637900.13
1546859.16
645378.22
365.0000000

8252
8252
8252
8252
8252

1 1705 mdtotal

fcpayment
totalcharge
totalexpenditure
NUMNIGHX

2309.32
8125.71
24454.16
8998.66
6.3601173

4586.37
22306.17
48659.21
23090.35
12.5818654

0
0
34.0000000
0
0

76777.34
628631.24
869502.46
648408.48
300.0000000

1705
1705
1705
1705
1705

2 209 mdtotal

fcpayment
totalcharge
totalexpenditure
NUMNIGHX

2161.17
8958.48
26465.19
9777.35
7.9282297

3267.31
12960.77
34836.55
13591.35
12.3346610

0
0
374.7100000
0
0

26462.87
90633.69
264901.98
93908.21
133.0000000

209
209
209
209
209

3 17 mdtotal

fcpayment
totalcharge
totalexpenditure
NUMNIGHX

1959.16
12493.18
35518.08
13265.28
12.7058824

3031.05
17787.87
43059.24
18696.60
21.7966876

0
0
632.3200000
0
1.0000000

11582.90
62770.70
148754.40
67023.64
90.0000000

17
17
17
17
17

4 2 mdtotal

fcpayment
totalcharge
totalexpenditure
NUMNIGHX

4380.75
21881.30
52052.35
23053.11
7.0000000

6195.32
8135.83
10003.52
6478.65
1.4142136

0
16128.40
44978.79
18472.01
6.0000000

8761.50
27634.20
59125.90
27634.20
8.0000000

2
2
2
2
2