Table 2.
Example Distributions of the Non–High-Dimensional Propensity Score Covariates in the Prematched Pharmaceutical Assistance Contract for the Elderly Data Set (United States, 1999–2002), “Standard” Covariate Set, Original Index Exposure Prevalence Data Set, and in the 3 Corresponding Fully Matched Data Sets
| Covariate | Prematched (n = 49,653) | Full, NNM | Full, DGM | Full, MDM | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Nonselective NSAIDs (n = 17,611)a | Selective COX-2 Inhibitors (n = 32,042) | Selective COX-2 Inhibitors (n = 17,611) | Selective COX-2 Inhibitors (n = 17,611) | Selective COX-2 Inhibitors (n = 17,611) | ||||||
| Mean (SD) | % | Mean (SD) | % | Mean (SD) | % | Mean (SD) | % | Mean (SD) | % | |
| Age | 77.79 (7.30) | 79.76 (7.24) | 78.15 (7.24) | 78.16 (7.23) | 78.95 (7.06) | |||||
| No. of generics prescribed | 7.43 (5.02) | 8.41 (5.25) | 7.56 (5.02) | 7.60 (5.03) | 6.75 (4.17) | |||||
| No. of medical visits | 7.74 (6.61) | 8.60 (6.67) | 7.86 (6.53) | 7.90 (6.59) | 6.96 (5.32) | |||||
| Charlson Comorbidity Index score | 1.85 (1.97) | 2.05 (2.01) | 1.85 (1.95) | 1.87 (1.96) | 1.47 (1.58) | |||||
| Male sex | 18.84 | 14.09 | 17.47 | 17.50 | 13.43 | |||||
| Race | ||||||||||
| White | 89.76 | 95.45 | 92.94 | 92.86 | 94.61 | |||||
| Black | 8.97 | 3.54 | 5.91 | 5.96 | 4.15 | |||||
| Other | 1.27 | 1.02 | 1.15 | 1.19 | 1.24 | |||||
| Comorbidities | ||||||||||
| Bleeding | 1.11 | 1.72 | 1.15 | 1.25 | 1.08 | |||||
| CHF | 24.58 | 30.36 | 24.76 | 25.17 | 18.80 | |||||
| Coronary disease | 14.78 | 16.43 | 14.89 | 14.87 | 9.60 | |||||
| Hypertension | 70.20 | 72.82 | 70.18 | 70.29 | 70.82 | |||||
| Rheumatoid arthritis | 2.70 | 5.00 | 3.02 | 2.84 | 2.54 | |||||
| Osteoarthritis | 33.49 | 48.53 | 35.16 | 35.01 | 41.23 | |||||
| Ulcer | 2.42 | 3.71 | 2.58 | 2.58 | 2.14 | |||||
| Hospitalization in prior year | 26.07 | 30.60 | 26.47 | 26.90 | 17.86 | |||||
| Nursing home resident | 5.66 | 8.34 | 6.18 | 6.23 | 3.64 | |||||
| Other medications | ||||||||||
| Corticosteroid | 7.80 | 8.74 | 8.08 | 8.17 | 5.48 | |||||
| Other gastrointestinal medication | 20.44 | 27.42 | 21.70 | 21.75 | 20.28 | |||||
| Warfarin | 6.55 | 13.27 | 7.00 | 7.02 | 5.95 | |||||
| Year of exposure initiation | ||||||||||
| 1999 | 48.79 | 41.68 | 47.09 | 47.11 | 43.21 | |||||
| 2000 | 23.91 | 29.94 | 24.90 | 24.79 | 29.10 | |||||
| 2001 | 20.00 | 21.28 | 20.49 | 20.73 | 21.08 | |||||
| 2002 | 7.30 | 7.09 | 7.52 | 7.38 | 6.62 | |||||
Abbreviations: CHF, congestive heart failure; COX-2, cyclooxygenase-2; DGM, digit-based greedy matching; MDM, Mahalanobis distance matching; NNM, nearest-neighbor matching; NSAID, nonsteroidal antiiinflammatory drug; SD, standard deviation.
a The nonselective NSAIDs covariate distribution is shown only once, because this distribution was the same in each data set.