Baseline characteristics among participants who did or did not use metformin
| Characteristic | PTDM cohort | PSM cohort | ||||
|---|---|---|---|---|---|---|
| No. (%) of patients who did not use metformin n = 20 347 | No. (%) of patients who did use metformin n = 20 347 | Absolute SMD | No. (%) of patients who did not use metformin n = 10 163 | No. (%) of patients who did use metformin n = 10 163 | Absolute SMD | |
| Age at baseline, yr | 0.048 | 0.048 | ||||
| 45–60 | 7818 (38.4) | 7871 (38.7) | 3801 (37.4) | 3679 (36.2) | ||
| 60–75 | 7967 (39.2) | 8067 (39.6) | 4158 (40.9) | 4087 (40.2) | ||
| ≥ 75 | 4562 (22.4) | 4409 (21.7) | 2204 (21.7) | 2397 (23.6) | ||
| Sex | 0 | 0.006 | ||||
| Female | 10 218 (50.2) | 10 218 (50.2) | 5152 (50.7) | 5270 (51.8) | ||
| Male | 10 129 (49.8) | 10 129 (49.8) | 5011 (49.3) | 4893 (48.2) | ||
| Year of DM diagnosis | 0.023 | 0.025 | ||||
| 2000–2003 | 8425 (41.4) | 8486 (41.7) | 3746 (36.9) | 3746 (36.9) | ||
| 2004–2007 | 5376 (26.4) | 5381 (26.4) | 2750 (27.1) | 2826 (27.8) | ||
| 2008–2012 | 6546 (32.2) | 6480 (31.8) | 3667 (36.1) | 3591 (35.3) | ||
| Urbanization | 0.088 | 0.043 | ||||
| Urban | 12 344 (60.7) | 11 673 (57.4) | 6013 (59.2) | 5823 (57.3) | ||
| Suburban | 5826 (28.6) | 6269 (30.8) | 3044 (30.0) | 3174 (31.2) | ||
| Rural | 2177 (10.7) | 2405 (11.8) | 1106 (10.9) | 1166 (11.5) | ||
| Insurance type | 0.214 | 0.015 | ||||
| Government | 1718 (8.4) | 1419 (7.0) | 754 (7.4) | 773 (7.6) | ||
| Privately held company | 10 361 (50.9) | 10 310 (50.7) | 5278 (51.9) | 5036 (49.6) | ||
| Agricultural organizations | 4418 (21.7) | 5008 (24.6) | 2327 (22.9) | 2444 (24.0) | ||
| Low-income | 177 (0.9) | 106 (0.5) | 55 (0.5) | 60 (0.6) | ||
| Non-labour force | 3324 (16.3) | 3196 (15.7) | 1601 (15.8) | 1682 (16.6) | ||
| Others | 349 (1.7) | 308 (1.5) | 148 (1.5) | 168 (1.6) | ||
| Level of adapted DCSI at baseline* | 0.114 | 0.015 | ||||
| 0 | 13 533 (66.5) | 12 601 (61.9) | 6359 (62.6) | 6259 (61.6) | ||
| 1 | 3024 (14.9) | 3670 (18.0) | 1885 (18.6) | 1865 (18.4) | ||
| 2 | 2524 (12.4) | 2666 (13.1) | 1311 (12.9) | 1372 (13.5) | ||
| 3 | 616 (3.0) | 758 (3.7) | 322 (3.2) | 356 (3.5) | ||
| 4 | 481 (2.4) | 491 (2.4) | 219 (2.2) | 241 (2.4) | ||
| ≥ 5 | 169 (0.8) | 161 (0.8) | 67 (0.7) | 70 (0.7) | ||
| Comorbidities at baseline | ||||||
| Osteoarthritis | 3351 (16.5) | 3073 (15.1) | 0.037 | 1686 (16.6) | 1714 (16.9) | 0.007 |
| Obesity | 47 (0.2) | 143 (0.7) | 0.069 | 47 (0.5) | 38 (0.4) | 0.014 |
| Hypertension | 9926 (48.8) | 12 135 (59.6) | 0.219 | 6286 (61.8) | 6173 (60.7) | 0.023 |
| Hyperlipidemia | 5789 (28.4) | 8121 (39.9) | 0.243 | 4179 (41.1) | 4106 (40.4) | 0.015 |
| Depression | 2874 (14.1) | 2179 (10.7) | 0.104 | 1245 (12.2) | 1299 (12.8) | 0.016 |
| COPD | 2430 (11.9) | 2301 (11.3) | 0.020 | 1204 (11.8) | 1238 (12.2) | 0.010 |
| Gout | 2247 (11.0) | 1839 (9.0) | 0.067 | 1283 (12.6) | 1010 (9.9) | 0.085 |
| RA | 199 (1.0) | 176 (0.9) | 0.012 | 80 (0.8) | 68 (0.7) | 0.014 |
| Osteoporosis | 1019 (5.0) | 804 (4.0) | 0.051 | 470 (4.6) | 426 (4.2) | 0.021 |
| Pain medications at baseline | ||||||
| Systemic corticosteroids | 5606 (27.6) | 5863 (28.8) | 0.028 | 2911 (28.6) | 2958 (29.1) | 0.010 |
| NSAIDs | 8807 (43.3) | 9309 (45.8) | 0.050 | 4764 (46.9) | 4700 (46.2) | 0.013 |
| Glucosamine | 873 (4.3) | 844 (4.2) | 0.007 | 419 (4.1) | 463 (4.6) | 0.021 |
| Opioids | 2068 (10.2) | 2139 (10.5) | 0.011 | 985 (9.7) | 1096 (10.8) | 0.036 |
| Other OAG drugs at baseline | ||||||
| Sulfonylureas | 1464 (7.2) | 11035 (54.2) | 1.185 | 1460 (14.4) | 1463 (14.4) | 0.001 |
| α-glucosidase inhibitors | 253 (1.2) | 1053 (5.2) | 0.224 | 244 (2.4) | 272 (2.7) | 0.018 |
| Thiazolidinediones | 123 (0.6) | 717 (3.5) | 0.206 | 118 (1.2) | 130 (1.3) | 0.011 |
| DPP-4 inhibitors | 64 (0.3) | 501 (2.5) | 0.184 | 61 (0.6) | 65 (0.6) | 0.005 |
| Insulin at baseline | 398 (2.0) | 1416 (7.0) | 0.244 | 354 (3.5) | 418 (4.1) | 0.033 |
Note: COPD = chronic obstructive pulmonary disease, DCSI = Diabetes Complications Severity Index, DM = diabetes mellitus, DPP-4 = dipeptidyl peptidase-4, NSAID = nonsteroidal anti-inflammatory drug, OAG = oral antihyperglycemic agent, PSM = propensity-score matching, PTDM = prescription time-distribution matching, RA = rheumatoid arthritis, SMD = standardized mean difference.
↵* A person who had both mild and severe complication would be classified as a severe case.