Table 1.
Clinical characteristics of metformin users stratified by dose, propensity score-matched non-users, and a non-user matched healthy cohort
| Characteristics | Healthy cohorts (n = 5846) | Metformin nonusers (n = 5846) | p-value* | Metformin users | |||
|---|---|---|---|---|---|---|---|
| All (n = 5846) | p-value# | Low cumulative exposure (n = 5587) | High cumulative exposure (n = 259) | ||||
| Age at index date | |||||||
| < 45 | 570 (9.8%) | 570 (9.8%) | 531 (9.1%) | 506 (9.1%) | 25 (9.7%) | ||
| 45 to 65 | 3030 (51.8%) | 3028 (51.8%) | 3067 (52.5%) | 2916 (52.2%) | 151 (58.3%) | ||
| ≥ 65 | 2246 (38.4%) | 2248 (38.5%) | 2248 (38.5%) | 2165 (38.8%) | 83 (32.0%) | ||
| Sex | > | ||||||
| Male | 2464 (42.1%) | 2464 (42.1%) | 2464 (42.1%) | 2360 (42.2%) | 104 (40.2%) | ||
| Female | 3382 (57.9%) | 3382 (57.9%) | 3382 (57.9%) | 3227 (57.8%) | 155 (59.8%) | ||
| aDCSI score | |||||||
| ≥ 3 | 0 (0%) | 1992 (34.1%) | 2010 (34.4%) | 1917 (34.3%) | 93 (35.9%) | ||
| 1 to 2 | 0 (0%) | 2312 (39.5%) | 2294 (39.2%) | 2187 (39.1%) | 107 (41.3%) | ||
| 0 | 100 (0%) | 1542 (26.4%) | 1542 (26.4%) | 1483 (26.5%) | 59 (22.8%) | ||
| Type 1 DM | 0 (0%) | 87 (1.5%) | – | 87 (1.5%) | 80 (1.4%) | 7 (2.7%) | |
| Liver cirrhosis | 0 (0%) | 23 (0.4%) | – | 23 (0.4%) | 22 (0.4%) | 1 (0.4%) | |
| Coexisting medical condition | |||||||
| Previous TB history | 76 (1.3%) | 384 (6.6%) | < 0.001 | 224 (3.8%) | < 0.001 | 220 (3.9%) | 4 (1.5%) |
| COPD | 0 (0%) | 487 (8.3%) | – | 352 (6.0%) | < 0.001 | 344 (6.2%) | 8 (3.1%) |
| Malignancy | 0 (0%) | 269 (4.6%) | – | 234 (4.0%) | 0.115 | 222 (4.0%) | 12 (4.6%) |
| Bronchiectasis | 0 (0%) | 115 (2.0%) | – | 64 (1.1%) | < 0.001 | 60 (1.1%) | 4 (1.5%) |
| Transplantation | 0 (0%) | 2 (0.03%) | – | 5 (0.09%) | 0.453 | 5 (0.1%) | 0 (0%) |
| HIV/AIDS | 0 (0%) | 2 (0.03%) | – | 2 (0.03%) | > 0.999 | 2 (0.04%) | 0 (0%) |
| Other co-morbidity$ | 0 (0%) | 105 (1.8%) | – | 96 (1.6%) | 0.569 | 92 (1.6%) | 4 (1.5%) |
| Urban contact area | 4084 (69.9%) | 3973 (68.0%) | 0.027 | 4035 (69.0%) | 0.223 | 3842 (68.8%) | 193 (74.5%) |
| Local TB incidence (/100,000 PYs) | 58.5 ± 16.1 | 59.7 ± 15.7 | 0.888 | 59.1 ± 15.7 | 0.035 | 59.1 ± 15.8 | 59.2 ± 14.98 |
| Low income | 391 (6.7%) | 410 (7.0%) | 0.487 | 426 (7.3%) | 0.591 | 408 (7.3%) | 18 (6.9%) |
| Medical visits in 3 months | 2.4 ± 2.5 | 3.8 ± 3.2 | < 0.001 | 4.0 ± 2.9 | < 0.001 | 4.0 ± 2.9 | 4.0 ± 2.6 |
| Statin users | 0 (0%) | 1108 (19.0%) | – | 1559 (26.7%) | < 0.001 | 1482 (26.5%) | 77 (29.7%) |
| Corticosteroid users | 0 (0%) | 80 (1.4%) | – | 67 (1.1%) | 0.322 | 64 (1.1%) | 3 (1.2%) |
| Insulin users | 0 (0%) | 2284 (39.1%) | – | 2399 (41.1%) | < 0.001 | 2278 (40.8%) | 121 (46.7%) |
| Other OHA users | 0 (0%) | 5211 (89.1%) | – | 5551 (95.0%) | < 0.001 | 5295 (94.8%) | 256 (98.8%) |
| Latent TB infection | 256 (4.4%) | 391 (6.7%) | < 0.001 | 200 (3.4%) | < 0.001 | 185 (3.3%) | 15 (5.8%) |
| IPT | 67 (1.1%) | 94 (1.6%) | 0.032 | 65 (1.1%) | 0.026 | 60 (1.1%) | 5 (1.9%) |
| Follow-up duration (days) | 582.4 ± 226.6 | 648.7 ± 177.9 | < 0.001 | 637.3 ± 166.1 | < 0.001 | 635.1 ± 167.5 | 685.7 ± 121.9 |
| Incident TB events | 49 (0.8%) | 116 (2.0%) | < 0.001 | 77 (1.3%) | 0.006 | 74 (1.3%) | 3 (1.2%) |
Abbreviations: aDCSI, adapted Diabetes Complications Severity Index; HIV/AIDS, human immunodeficiency virus/acquired immunodeficiency syndrome; COPD, chronic obstructive pulmonary disease; DM, diabetes mellitus; IPT, early adherent isoniazid preventive therapy; OHA, oral hypoglycemic agents; PY, person-years; TB, tuberculosis
Data are expressed as the number (%) unless otherwise specified
* p value of healthy cohorts vs. metformin nonusers and # p value of metformin users vs. nonusers in paired t test for continuous variables and McNemar test for categorical variables
$ Including pneumoconiosis, psoriasis, rheumatoid arthritis, and ankylosing spondylitis