Table. Baseline Characteristics of the Study Groups Before and After Matching.
| Characteristic | Unmatched, No. (%) | Standardized differencea | Matched, No. (%) | Standardized differencea | ||
|---|---|---|---|---|---|---|
| HDHP group (n = 158 179) | Control group (n = 1 641 225) | HDHP group (n = 156 962) | Control group (n = 1 467 758) | |||
| Age, mean (SD), y | 52.7 (6.7) | 52.9 (7.0) | −0.023 | 52.7 (6.7) | 52.9 (6.9) | −0.028 |
| Female | 73 830 (46.7) | 791 364 (48.2) | −0.031 | 73 290 (46.7) | 687 802 (46.9) | −0.003 |
| Diabetesb | 28 454 (18.0) | 298 288 (18.2) | 0.044 | 29 407 (18.7) | 274 986 (18.7) | 0 |
| Cardiovascular diseasec | 9778 (6.2) | 88 746 (5.4) | 10 174 (6.5) | 95 137 (6.5) | ||
| Hypertension or hyperlipidemiad | 119 947 (75.8) | 1 254 191 (76.4) | 117 381 (74.8) | 1 097 634 (74.8) | ||
| Living in neighborhoods with below-poverty levels, %e | ||||||
| <5.0 | 38 107 (24.1) | 430 006 (26.2) | 0.062 | 37 825 (24.1) | 361 385 (24.6) | 0.056 |
| 5.0-9.9 | 42 764 (27.0) | 452 258 (27.6) | 42 479 (27.1) | 408 051 (27.8) | ||
| 10.0-19.9 | 48 342 (30.6) | 479 843 (29.2) | 48 085 (30.6) | 448 519 (30.6) | ||
| ≥20 | 28 703 (18.1) | 277 422 (16.9) | 28 561 (18.2) | 249 599 (17.0) | ||
| Missing | 263 (0.2) | 1696 (0.1) | 12 (0.0) | 204 (0.0) | ||
| Living in neighborhoods with educational levels below high school, %e | ||||||
| <15.0 | 112 468 (71.1) | 1 190 091 (72.5) | 0.088 | 111 743 (71.2) | 1 069 721 (72.9) | 0.049 |
| 15.0-24.9 | 30 309 (19.2) | 299 086 (18.2) | 30 137 (19.2) | 268 160 (18.3) | ||
| 25.0-39.9 | 12 295 (7.8) | 123 915 (7.6) | 12 240 (7.8) | 106 726 (7.3) | ||
| ≥40.0 | 2847 (1.8) | 26 468 (1.6) | 2833 (1.8) | 22 975 (1.6) | ||
| Missing educational level | 260 (0.2) | 1665 (0.1) | 9 (0.0) | 176 (0.0) | ||
| Race/ethnicityf | ||||||
| Asian | 3508 (2.2) | 47 149 (2.9) | 0.127 | 3466 (2.2) | 32 196 (2.2) | 0.038 |
| Black | 3580 (2.3) | 50 816 (3.1) | 3563 (2.3) | 33 391 (2.3) | ||
| Hispanic | 12 085 (7.6) | 134 564 (8.2) | 11 943 (7.6) | 109 861 (7.5) | ||
| Mixed | 31 412 (19.9) | 369 955 (22.5) | 31 235 (19.9) | 299 128 (20.4) | ||
| White | 107 400 (67.9) | 1 037 425 (63.2) | 106 749 (68.0) | 993 027 (67.7) | ||
| Missing | 194 (0.1) | 1316 (0.1) | 6 (0.0) | 154 (0.0) | ||
| Age category, y | ||||||
| 40-49 | 53 136 (33.6) | 555 950 (33.9) | 0.054 | 52 823 (33.7) | 488 731 (33.3) | 0.050 |
| 50-59 | 74 708 (47.2) | 730 576 (44.5) | 74 138 (47.2) | 673 347 (45.9) | ||
| 60-64 | 30 335 (19.2) | 354 699 (21.6) | 30 001 (19.1) | 305 680 (20.8) | ||
| ACG score, mean (SD)g | 1.5 (2.3) | 1.5 (2.3) | −0.018 | 1.5 (2.2) | 1.5 (2.2) | 0.007 |
| US region | ||||||
| South | 76 860 (48.6) | 746 850 (45.5) | 0.212 | 76 789 (48.9) | 762 632 (52.0) | 0.084 |
| West | 14 917 (9.4) | 204 120 (12.4) | 14 904 (9.5) | 148 105 (10.1) | ||
| Midwest | 54 364 (34.4) | 486 910 (29.7) | 54 315 (34.6) | 473 900 (32.3) | ||
| Northeast | 10 955 (6.9) | 195 252 (11.9) | 10 954 (7.0) | 83 121 (5.7) | ||
| Missing | 1083 (0.7) | 8093 (0.5) | ||||
| Outpatient copayment, median (SD), $ | 19.3 (6.2) | 16.8 (6.9) | 0.383 | 19.3 (6.2) | 18.6 (6.4) | 0.107 |
| Baseline total costs, (SD), $ | 10 784 (25 611) | 11 127 (26 942) | −0.013 | 10 751 (25443) | 10 529 (24 124) | 0.009 |
| Out-of-pocket spending, $ | ||||||
| 0.00-500.00 | 57 763 (36.5) | 689 791 (42.0) | 0.171 | 57 192 (36.4) | 535 842 (36.5) | 0.066 |
| 500.01-999.99 | 38 205 (24.2) | 422 100 (25.7) | 38 016 (24.2) | 368 264 (25.1) | ||
| 1000.00-2499.99 | 44 173 (27.9) | 404 436 (24.6) | 43 914 (28.0) | 415 363 (28.3) | ||
| ≥2500.00 | 18 038 (11.4) | 124 898 (7.6) | 17 840 (11.4) | 148 289 (10.1) | ||
| Employer size, No. of enrollees | ||||||
| 0-99 | 101 951 (64.5) | 317 329 (19.3) | 1.299 | 100 970 (64.3) | 920 475 (62.7) | 0.124 |
| 100-999 | 49 139 (31.1) | 537 972 (32.8) | 48 908 (31.2) | 431 698 (29.4) | ||
| ≥1000 | 7089 (4.5) | 785 924 (47.9) | 7084 (4.5) | 115 585 (7.9) | ||
Abbreviation: HDHP, high-deductible health plan.
a
Closer to zero indicates greater similarity.
b
Based on Johns Hopkins ACG software definition of diabetes.
c
Based on Johns Hopkins ACG software definition of cardiovascular disease.
d
Based on Johns Hopkins ACG software definition of hypertension/hyperlipidemia.
e
Based on 2008-2012 American Community Survey data at census tract level.
f
Definitions available in Methods Covariates subsection.
g
Based on Johns Hopkins ACG Software; mean score in overall sample (members in and not in this cohort) was 0.62 to 0.82 from 2003 to 2014.