Table 2.
Baseline characteristics of patients before and after propensity score matching
| No. (%) of patients | ||||||||
|---|---|---|---|---|---|---|---|---|
| Before propensity score matching | After propensity score matching | |||||||
| No metformin (n = 2222) | Metformin (n = 1377) | Std diff | p value | No metformin (n = 1100) | Metformin (n = 1100) | Std diff | p value | |
| Age, years | < 0.001 | 0.88 | ||||||
| Mean | 73.4 (9.4) | 72.2 (8.5) | – | 72.4 (9.4) | 72.5 (8.8) | – | ||
| Median (IQR) | 75 (68–82) | 73 (67–78) | – | 73 (67–80) | 74 (68–79) | – | ||
| Age group, years | < 0.001 | 0.63 | ||||||
| 18–54 | 89 (4.0) | 45 (3.3) | 0.0% | 48 (4.4) | 40 (3.6) | 0.0% | ||
| 55–64 | 278 (12.5) | 187 (13.6) | 3.2% | 155 (14.1) | 146 (13.3) | 0.0% | ||
| 65–74 | 729 (32.8) | 572 (41.5) | 18.1% | 419 (38.1) | 411 (37.4) | 0.6% | ||
| 75 + | 1126 (50.7) | 573 (41.6) | 0.0% | 478 (43.5) | 503 (45.7) | 0.0% | ||
| Sex | 0.02 | 0.73 | ||||||
| Female | 1042 (46.9) | 591 (42.9) | 0.0% | 511 (46.5) | 503 (45.7) | 2.0% | ||
| Male | 1180 (53.1) | 786 (57.1) | 8.0% | 589 (53.5) | 597 (54.3) | 0.0% | ||
| Race | 0.004 | 0.99 | ||||||
| White | 1332 (59.9) | 794 (57.7) | 7.9% | 645 (58.6) | 647 (58.8) | 0.0% | ||
| Black | 334 (15.0) | 170 (12.3) | 0.0% | 158 (14.4) | 151 (13.7) | 0.0% | ||
| Hispanic | 358 (16.1) | 263 (19.1) | 7.9% | 191 (17.4) | 193 (17.5) | 0.0% | ||
| Asian | 64 (2.9) | 60 (4.4) | 2.1% | 35 (3.2) | 34 (3.1) | 0.2% | ||
| Unknown | 134 (6.0) | 90 (6.5) | 0.0% | 71 (6.5) | 75 (6.8) | 0.8% | ||
| Insurance | 0.85 | 0.32 | ||||||
| Commercial | 245 (11.0) | 149 (10.8) | – | 135 (12.3) | 120 (10.9) | – | ||
| Medicare advantage | 1977 (89.0) | 1228 (89.2) | – | 965 (87.7) | 980 (89.1) | – | ||
| Census Region | 0.54 | 0.71 | ||||||
| Midwest | 535 (24.1) | 324 (23.5) | 0.0% | 243 (22.1) | 264 (24.0) | 0.0% | ||
| Northeast | 336 (15.1) | 200 (14.5) | 0.0% | 166 (15.1) | 156 (14.2) | 3.0% | ||
| South | 1167 (52.5) | 720 (52.3) | 0.0% | 600 (54.5) | 586 (53.3) | 0.9% | ||
| West | 184 (8.3) | 133 (9.7) | 4.8% | 91 (8.3) | 94 (8.5) | 0.0% | ||
| Year | 0.60 | 1.00 | ||||||
| 2014 | 392 (17.6) | 224 (16.3) | 0.0% | 187 (17.0) | 187 (17.0) | 2.0% | ||
| 2015 | 349 (15.7) | 204 (14.8) | 0.0% | 168 (15.3) | 171 (15.5) | 0.0% | ||
| 2016 | 416 (18.7) | 254 (18.4) | 0.0% | 217 (19.7) | 210 (19.1) | 1.7% | ||
| 2017 | 466 (21.0) | 288 (20.9) | 0.0% | 229 (20.8) | 229 (20.8) | 0.0% | ||
| 2018 | 409 (18.4) | 273 (19.8) | 3.6% | 202 (18.4) | 206 (18.7) | 0.0% | ||
| 2019* | 190 (8.6) | 134 (9.7) | 4.1% | 97 (8.8) | 97 (8.8) | 0.0% | ||
| Anti-fibrotics | 401 (18.0) | 391 (28.4) | 24.7% | < 0.001 | 260 (23.6) | 255 (23.2) | 0.0% | 0.80 |
| Baseline medications | ||||||||
| Steroids | 1009 (45.4) | 600 (43.6) | 0.0% | 0.28 | 505 (45.9) | 484 (44.0) | 2.0% | 0.37 |
| ACE inhibitor | 530 (23.9) | 469 (34.1) | 22.6% | < 0.001 | 344 (31.3) | 330 (30.0) | 1.7% | 0.52 |
| ARB | 558 (25.1) | 433 (31.4) | 14.1% | < 0.001 | 331 (30.1) | 322 (29.3) | 0.1% | 0.67 |
| Statins | 1296 (58.3) | 1005 (73.0) | 31.2% | < 0.001 | 756 (68.7) | 739 (67.2 | 0.0% | 0.44 |
| SGLT2 | 28 (1.3) | 50 (3.6) | – | < 0.001 | 13 (1.2) | 29 (2.6) | – | 0.01 |
| Insulin | 664 (29.9) | 248 (18.0) | 0.0% | < 0.001 | 231 (21.0) | 232 (21.1) | 0.0% | 0.96 |
| DPP4 | 229 (10.3) | 176 (12.8) | – | 0.02 | 143 (13.0) | 120 (10.9) | – | 0.13 |
| GLP-1 | 50 (2.3) | 63 (4.6) | – | 0.00 | 33 (3.0) | 42 (3.8) | – | 0.29 |
| Sulfonylureas | 483 (21.7) | 426 (30.9) | 21.0% | < 0.001 | 294 (26.7) | 294 (26.7) | 0.0% | 1.0 |
| Glitazones | 58 (2.6) | 71 (5.2) | – | 0.00 | 38 (3.5) | 51 (4.6) | – | 0.16 |
| HbA1c lab result | 0.00 | 0.04 | ||||||
| Mean (SD) | 6.9 (1.3) | 7.0 (1.2) | – | 6.9 (1.3) | 7.0 (1.2) | – | ||
| Median (IQR) | 6.6 (6.1–7.5) | 6.8 (6.2–7.5) | – | 6.6 (6.1–7.4) | 6.8 (6.2–7.5) | – | ||
| Primary care office visit | 1821 (82.0) | 1209 (87.8) | – | < 0.001 | 939 (85.4) | 964 (87.6) | – | 0.12 |
| Pulmonary office visit | 1237 (55.7) | 843 (61.2) | 11.3% | 0.00 | 652 (59.3) | 659 (59.9) | 0.7% | 0.76 |
| Baseline hospitalizations | < 0.001 | 0.92 | ||||||
| 0 | 1192 (53.6) | 925 (67.2) | 27.9% | 693 (63.0) | 701 (63.7) | 0.0% | ||
| 1 | 636 (28.6) | 326 (23.7) | 0.0% | 280 (25.5) | 277 (25.2) | 0.0% | ||
| 2 + | 394 (17.7) | 126 (9.2) | 0.0% | 127 (11.5) | 122 (11.1) | 0.8% | ||
| DME, oxygen | 1001 (45.0) | 587 (42.6) | 0.0% | 0.16 | 479 (43.5) | 473 (43.0) | 0.4% | 0.80 |
| Current smoker | 646 (29.1) | 395 (28.7) | 0.0% | 0.80 | 342 (31.1) | 321 (29.2) | 0.2% | 0.33 |
| Elixhauser comorbidity count | < 0.001 | 0.93 | ||||||
| Mean (SD) | 6.9 (3.1) | 5.8 (2.7) | – | 6.1 (2.7) | 6.1 (2.8) | – | ||
| Median (IQR) | 7 (5–9) | 6 (4–7) | – | 6 (4–8) | 6 (4–8) | – | ||
| Elixhauser conditions | ||||||||
| Cardiac arrhythmia | 905 (40.7) | 405 (29.4) | 0.0% | < 0.001 | 357 (32.5) | 364 (33.1) | 1.3% | 0.75 |
| Congestive heart failure | 941 (42.3) | 417 (30.3) | 0.0% | < 0.001 | 371 (33.7) | 376 (34.2) | 4.3% | 0.82 |
| Chronic pulmonary disease | 1525 (68.6) | 895 (65.0) | 0.0% | 0.02 | 737 (67.0) | 722 (65.6) | 0.0% | 0.50 |
| Depression | 368 (16.6) | 176 (12.8) | 0.0% | 0.00 | 160 (14.5) | 156 (14.2) | 0.0% | 0.81 |
| Hypertension | 1828 (82.3) | 1130 (82.1) | 0.0% | 0.88 | 916 (83.3) | 908 (82.5) | 1.4% | 0.65 |
| Obesity | 371 (16.7) | 227 (16.5) | 0.0% | 0.87 | 186 (16.9) | 183 (16.6) | 1.8% | 0.86 |
| Pulmonary circulation disorder | 512 (23.0) | 300 (21.8) | 0.0% | 0.38 | 250 (22.7) | 248 (22.5) | 1.9% | 0.92 |
| Renal failure | 764 (34.4) | 206 (15.0) | 0.0% | < 0.001 | 186 (16.9) | 203 (18.5) | 0.0% | 0.34 |
| Rheumatoid arthritis | 300 (13.5) | 167 (12.1) | 0.0% | 0.23 | 148 (13.5) | 143 (13.0) | 1.3% | 0.75 |
| Valvular disease | 575 (25.9) | 276 (20.0) | 0.0% | 0.00 | 239 (21.7) | 238 (21.6) | 0.0% | 0.96 |
SGLT2 sodium-glucose co-transporter-2, DPP4 dipeptidyl peptidase-4, GLP-1 glucagon-like peptide-1, DME durable medical equipment
*From January 1,2019–June 30, 2019