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Table 1 Clinical characteristics of metformin users stratified by dose, propensity score-matched non-users, and a non-user matched healthy cohort

From: Impact of metformin use among tuberculosis close contacts with diabetes mellitus in a nationwide cohort study

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%)
  1. 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
  2. Data are expressed as the number (%) unless otherwise specified
  3. * 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
  4. $ Including pneumoconiosis, psoriasis, rheumatoid arthritis, and ankylosing spondylitis