Table 1. Comparison of baseline characteristics between metformin never users and ever users in the original sample and in the propensity score matched sample.
| Variable | Original sample | Matched sample | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Never users (n = 16263) | Ever users (n = 288198) | P | SD | Never users (n = 16263) | Ever users (n = 16263) |
P | SD | |||||
| n | % | n | % | n | % | n | % | |||||
| Demographic data | ||||||||||||
| Age (years) | 59.1±10.4 | 56.6±10.2 | <0.0001 | −25.14 | 59.1±10.4 | 59.4±9.7 | 0.0197 | 3.54 | ||||
| Sex (men) | 9332 | 57.4 | 155199 | 53.9 | <0.0001 | −7.31 | 9332 | 57.4 | 9437 | 58.0 | 0.2386 | 0.98 |
| Major comorbidities | ||||||||||||
| Hypertension | 11995 | 73.8 | 198483 | 68.9 | <0.0001 | −11.31 | 11995 | 73.8 | 12033 | 74.0 | 0.6315 | 0.98 |
| Dyslipidemia | 9855 | 60.6 | 197488 | 68.5 | <0.0001 | 17.23 | 9855 | 60.6 | 9690 | 59.6 | 0.0617 | −1.56 |
| Diabetes-related complications | ||||||||||||
| Nephropathy | 4139 | 25.5 | 46223 | 16.0 | <0.0001 | −25.22 | 4139 | 25.5 | 4123 | 25.4 | 0.8385 | −1.01 |
| Eye disease | 1529 | 9.4 | 41653 | 14.5 | <0.0001 | 15.66 | 1529 | 9.4 | 1341 | 8.3 | 0.0002 | −4.72 |
| Stroke | 4021 | 24.7 | 54814 | 19.0 | <0.0001 | −14.73 | 4021 | 24.7 | 3947 | 24.3 | 0.3401 | −0.90 |
| IHD | 6218 | 38.2 | 98033 | 34.0 | <0.0001 | −9.33 | 6218 | 38.2 | 6256 | 38.5 | 0.6648 | 0.67 |
| PAD | 2516 | 15.5 | 45915 | 15.9 | <0.0001 | 1.20 | 2516 | 15.5 | 2505 | 15.4 | 0.8659 | −0.32 |
| Antidiabetic drugs | ||||||||||||
| Sulfonylurea | 11832 | 72.8 | 189914 | 65.9 | <0.0001 | −11.51 | 11832 | 72.8 | 12560 | 77.2 | <0.0001 | 11.65 |
| Meglitinide | 1338 | 8.2 | 10353 | 3.6 | <0.0001 | −20.99 | 1338 | 8.2 | 1245 | 7.7 | 0.0565 | −1.87 |
| Acarbose | 1835 | 11.3 | 14531 | 5.0 | <0.0001 | −22.46 | 1835 | 11.3 | 1718 | 10.6 | 0.0376 | −4.03 |
| Insulin | 1351 | 8.3 | 6100 | 2.1 | <0.0001 | −29.42 | 1351 | 8.3 | 990 | 6.1 | <0.0001 | −10.71 |
| Pioglitazone | 403 | 2.5 | 7024 | 2.4 | 0.7428 | 0.31 | 403 | 2.5 | 435 | 2.7 | 0.2627 | 0.51 |
| Rosiglitazone | 483 | 3.0 | 12961 | 4.5 | <0.0001 | 8.43 | 483 | 3.0 | 441 | 2.7 | 0.1610 | −1.98 |
| Potential risk factors of oral cancer | ||||||||||||
| COPD | 6521 | 40.1 | 110809 | 38.5 | <0.0001 | −3.84 | 6521 | 40.1 | 6599 | 40.6 | 0.3780 | 1.19 |
| Tobacco abuse | 266 | 1.6 | 5915 | 2.1 | 0.0002 | 3.19 | 266 | 1.6 | 247 | 1.5 | 0.3978 | −0.89 |
| Alcohol-related diagnoses | 1037 | 6.4 | 15451 | 5.4 | <0.0001 | −4.77 | 1037 | 6.4 | 1059 | 6.5 | 0.6193 | 0.21 |
| Medications that may affect cancer risk | ||||||||||||
| ACEI/ARB | 9609 | 59.1 | 163730 | 56.8 | <0.0001 | −5.07 | 9609 | 59.1 | 9660 | 59.4 | 0.5650 | 0.74 |
| Statin | 6438 | 39.6 | 127216 | 44.1 | <0.0001 | 9.44 | 6438 | 39.6 | 6354 | 39.1 | 0.3403 | −0.82 |
| Aspirin | 7672 | 47.2 | 133390 | 46.3 | 0.0267 | −2.16 | 7672 | 47.2 | 7560 | 46.5 | 0.2133 | −1.04 |
| NSAID | 16180 | 99.5 | 287188 | 99.7 | 0.0009 | 2.70 | 16180 | 99.5 | 16186 | 99.5 | 0.6344 | 0.90 |
Age is expressed as mean ± standard deviation
Abbreviations
SD: standardized difference, IHD: ischemic heart disease, PAD: peripheral arterial disease, COPD: chronic obstructive pulmonary disease, ACEI/ARB: angiotensin converting enzyme inhibitor/angiotensin receptor blocker, NSAID: non-steroidal anti-inflammatory drugs (excluding aspirin)