Table 3.
Comparison of Baseline (2005) Variables Following Application of Coarsened Exact Matching (CEM) and Propensity Score Matching (PSM)*
| |
Post CEM† |
Post PSM |
|
||
|---|---|---|---|---|---|
| Explanatory Variables | Treatment (n=7833) | Comparison (n=7221) | Treatment (n=7833) | Comparison (n=5295) | % Δ‡ |
| Age | 51.41 | 51.22 | 51.37 | 50.84 | −0.4% CEM ∥−1% PSM |
| (0.0579) | (0.0408) | (0.0572) | (0.0276) | ||
| Sex | 0.61 | 0.61 | 0.61 | 0.60 | 0% CEM ∥ −0.9% PSM |
| (0.0033) | (0.0033) | (0.0034) | (0.0018) | ||
| Disease program | |||||
| CAD | 0.24 | 0.23 | 0.24 | 0.23 | −5% CEM ∥ −1.6% PSM |
| (0.0029) | (0.0008) | (0.0029) | (0.0021) | ||
| CHF | 0.03 | 0.03 | 0.03 | 0.03 | 16.8% CEM ∥ 11% PSM |
| (0.0011) | (0.0002) | (0.0011) | (0.0005) | ||
| COPD | 0.07 | 0.08 | 0.07 | 0.08 | 14.4% CEM ∥ 13.6% PSM |
| (0.0017) | (0.0004) | (0.0017) | (0.0007) | ||
| Diabetes | 0.67 | 0.66 | 0.67 | 0.66 | −0.4% CEM ∥−1.3% PSM |
| (0.0032) | (0.0011) | (0.0032) | (0.0021) | ||
| Base Member Months | 11.78 | 11.93 | 11.78 | 11.89 | 1.3% CEM ∥ 1% PSM |
| (0.0068) | (0.0007) | (0.0067) | (0.0011) | ||
| 2004 Allowed PMPM Medical Costs ($) | 564.44 | 532.63 | 567.76 | 523.48 | −5.6% CEM ∥−7.8% PSM |
| (6.9170) | (1.2736) | (7.1124) | (3.3224) | ||
| Allowed PMPM Medical Costs ($) | 622.24 | 575.17 | 626.62 | 594.26 | −7.6% CEM ∥−5.2% PSM |
| (5.2277) | (3.5667) | (5.2750) | (2.6700) | ||
| Exceed Average Medical Costs | 0.34 | 0.34 | 0.34 | 0.33 | −1.6% CEM ∥−3% PSM |
| (0.0030) | (0.0017) | (0.0030) | (0.0017) | ||
| Primary Plan State | 0.93 | 0.93 | 0.93 | 0.79 | 0% CEM ∥−15.8% PSM |
| (0.0016) | (0.0016) | (0.0016) | (0.0039) | ||
| Plan Type | 1.82 | 1.83 | 1.84 | 1.66 | 0.3% CEM ∥−9.9% PSM |
| (0.0076) | (0.0076) | (0.0077) | (0.0162) | ||
| Duration Since Chronic Disease Indication Dummy | 0.37 | 0.37 | 0.37 | 0.41 | 0% CEM ∥ 10% PSM |
| (0.0033) | (0.0033) | (0.0033) | (0.0019) | ||
| Inpatient Stays | 0.50 | 0.50 | 0.51 | 0.57 | −0.6% CEM ∥ 11.2% PSM |
| (0.0119) | (0.0094) | (0.0120) | (0.0066) | ||
| Emergency Department Visits | 0.20 | 0.21 | 0.21 | 0.24 | 4.9% CEM ∥ 12.4% PSM |
| (0.0048) | (0.0022) | (0.0051) | (0.0029) | ||
| Outpatient Visits | 12.71 | 13.24 | 12.76 | 13.14 | 4.1% CEM ∥ 3% PSM |
| (0.0781) | (0.0362) | (0.0789) | (0.0441) | ||
| Physician Visits | 19.71 | 15.99 | 19.73 | 15.27 | −18.9% CEM ∥−22.6% PSM |
| (0.0965) | (0.0438) | (0.0957) | (0.0571) | ||
| 2004 ICD9 Count | 54.35 | 52.55 | 54.43 | 49.57 | −3.3% CEM ∥−8.9% PSM |
| (0.3434) | (0.1017) | (0.3466) | (0.1710) | ||
| ICD9 Count | 55.88 | 56.37 | 56.07 | 57.55 | 0.9% CEM ∥ 2.6% PSM |
| (0.2703) | (0.1358) | (0.2719) | (0.1764) | ||
| CPT4 Rank | 15.83 | 16.27 | 15.86 | 16.02 | 2.8% CEM ∥ 1% PSM |
| (0.0882) | (0.0354) | (0.0888) | (0.0464) | ||
| Prescription Medication (NDC) Count | 35.15 | 27.81 | 35.18 | 26.54 | −20.9% CEM ∥−24.5% PSM |
| (0.1917) | (0.0787) | (0.1902) | (0.1003) | ||
| Clinical Risk Group (CRG) Score | 233.81 | 231.85 | 233.83 | 229.02 | −0.8% CEM ∥−2.1% PSM |
| (0.2242) | (0.0790) | (0.2227) | (0.2912) | ||
| Weighted Average Disease Severity | 3.88 | 3.85 | 3.88 | 3.81 | −0.8% CEM ∥−1.9% PSM |
| (0.0089) | (0.0035) | (0.0089) | (0.0054) | ||
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.
CEM results are based on application of CEM-derived weights.
Independent, relative percent difference in postmatch values (by Explanatory Variable) for comparison and treatment group members by matching method. As an example, for the explanatory variable Age, the delta is computed as: (51.22−51.41)/51.41=−0.4% [CEM] and (50.84−51.37)/51.37=−1 % [PSM].
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.