Table 4.
Comparison of Baseline (2005) Variables for Members Included or Excluded between Coarsened Exact Matching (CEM) and Propensity Score Matching (PSM)*
| |
Post-CEM Match (Included in CEM, Excluded in PSM) |
Post-PSM Match (Included In PSM, Excluded in CEM) |
|
||
|---|---|---|---|---|---|
| Explanatory Variables | Treatment (n=.)† | Comparison (n=1994) | Treatment (n=49) | Comparison (n=37) | % Δ‡ |
| Age | AMR | 50.23 | 44.55 | 44.97 | −10% |
| (0.2047) | (0.9669) | (1.3747) | |||
| Sex | AMR | 0.50 | 0.41 | 0.38 | −24% |
| (0.0351) | (0.0389) | (0.0794) | |||
| Disease program | |||||
| CAD | AMR | 0.13 | 0.22 | 0.23 | 85% |
| (0.0155) | (0.0364) | (0.0545) | |||
| CHF | AMR | 0.04 | 0.05 | 0.02 | −39% |
| (0.0018) | (0.0194) | (0.0229) | |||
| COPD | AMR | 0.10 | 0.07 | 0.14 | 43% |
| (0.0037) | (0.0219) | (0.0334) | |||
| Diabetes | AMR | 0.74 | 0.66 | 0.60 | −18% |
| (0.0160) | (0.0405) | (0.0612) | |||
| Base Member Months | AMR | 11.87 | 11.36 | 11.79 | −1% |
| (0.0080) | (0.1351) | (0.0529) | |||
| 2004 Allowed PMPM Medical Costs ($) | AMR | 374.56 | 1,094.25 | 441.45 | 18% |
| (11.4938) | (235.0966) | (90.8875) | |||
| Allowed PMPM Medical Costs ($) | AMR | 465.35 | 1,322.08 | 1,099.00 | 136% |
| (26.1465) | (112.2179) | (128.3874) | |||
| Exceed Average Medical Costs | AMR | 0.26 | 0.68 | 0.72 | 178% |
| (0.0131) | (0.0396) | (0.0584) | |||
| Primary Plan State | AMR | 0.27 | 0.75 | 0.41 | 52% |
| (0.0211) | (0.0386) | (0.0769) | |||
| Plan Type | AMR | 2.40 | 4.78 | 3.85 | 60% |
| (0.0821) | (0.1664) | (0.3932) | |||
| Duration Since Chronic Disease Indication Dummy | AMR | 0.54 | 0.34 | 0.61 | 13% |
| (0.0373) | (0.0383) | (0.0856) | |||
| Inpatient Stays | AMR | 0.54 | 1.96 | 2.02 | 273% |
| (0.0677) | (0.2651) | (0.4067) | |||
| Emergency Department Visits | AMR | 0.22 | 1.52 | 1.84 | 719% |
| (0.0090) | (0.2077) | (0.4763) | |||
| Outpatient Visits | AMR | 11.13 | 19.33 | 20.07 | 80% |
| (0.2870) | (1.5772) | (1.3314) | |||
| Physician Visits | AMR | 9.65 | 23.03 | 19.23 | 99% |
| (0.5128) | (1.8850) | (1.5928) | |||
| 2004 ICD9 Count | AMR | 29.59 | 67.47 | 45.37 | 53% |
| (0.7897) | (7.5389) | (5.6799) | |||
| ICD9 Count | AMR | 53.35 | 86.63 | 98.51 | 85% |
| (1.3111) | (4.7918) | (6.5595) | |||
| CPT4 Rank | AMR | 14.09 | 20.76 | 21.02 | 49% |
| (0.2699) | (1.7155) | (2.0439) | |||
| Prescription Medication (NDC) Count | AMR | 16.73 | 40.06 | 30.57 | 83% |
| (0.8627) | (3.3940) | (2.7375) | |||
| Clinical Risk Group (CRG) Score | AMR | 212.42 | 238.20 | 230.91 | 9% |
| (1.1264) | (2.3102) | (6.1218) | |||
| Weighted Average Disease Severity | AMR | 3.49 | 4.01 | 4.23 | 21% |
| (0.0336) | (0.1199) | (0.1981) | |||
Results based on CEM stratification {DURATION_SINCE_CHRONIC_DISEASE_INDICATION_DUMMY, AGE40_DUMMY, GENDER, IP_DUMMY, ED99_DUMMY, PLAN_STATE_DUMMY, PLAN_TYPE}; all values based on the average of 250 simple random samples taken with replacement, with the treatment group sampled (simple random with replacement) at a rate equal to the original comparison group (analyzed comparison group sampled up to 1.5 times the original size). Members were between the ages of 18 and 64.9 years, evidenced to have a chronic condition of coronary artery disease, congestive heart failure, chronic obstructive pulmonary disease, and/or diabetes (based on administrative claims data), and excluded if medical costs in baseline or program year exceeded the 99th percentile, or if their change in costs over these 2 periods exceeded the 99th percentile. Standard deviation in parentheses.
AMR denotes “All Members Retained,” implying CEM and PSM retained identical treatment group members.
Independent, relative percent difference in postmatch values (by Explanatory Variable) between CEM and PSM for comparison group members. As an example, for the explanatory variable Age, the delta is computed as: (44.97−50.23)/50.23=−10%.
CAD, coronary artery disease; CHF, congestive heart failure; COPD, chronic obstructive pulmonary disease; CPT, Current Procedural Terminology; ICD9, International Classification of Diseases, Ninth Revision; NDC, National Drug Code; PMPM, per member per month.