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Table 1 Baseline characteristics between metformin monotherapy and control groups before and after matching

From: Effect of metformin monotherapy on cardiovascular diseases and mortality: a retrospective cohort study on Chinese type 2 diabetes mellitus patients

Factor Full cohort with complete case Propensity score-matched cohort
Total (N = 11,293) MM group (N = 7493) Control group (N = 3800) P value Total (N = 6800) MM group (N = 3400) Control group (N = 3400) P value
Socio-demographic (%, n)
 Age (mean ± SD, n), years 62.05 ± 10.83 (11,293) 61.70 ± 10.75 (7493) 62.75 ± 10.97 (3800) <0.001* 62.57 ± 10.78 (6800) 62.64 ± 10.58 (3400) 62.51 ± 10.98 (3400) 0.621
 Gender     0.728     0.711
  Female 59.51 % (6721) 59.63 % (4468) 59.29 % (2253)   59.31 % (4033) 59.09 % (2009) 59.53 % (2024)  
  Male 40.49 % (4572) 40.37 % (3025) 40.71 % (1547)   40.69 % (2767) 40.91 % (1391) 40.47 % (1376)  
 Smoking status     <0.001*     0.878
  Non-smoker 92.69 % (10,468) 91.82 % (6880) 94.42 % (3588)   94.04 % (6395) 94.09 % (3199) 94.00 % (3196)  
  Smoker 7.31 % (825) 8.18 % (613) 5.58 % (212)   5.96 % (405) 5.91 % (201) 6.00 % (204)  
 Alcohol status     0.990     0.634
  Non-drinker 84.77 % (9573) 84.77 % (6352) 84.76 % (3221)   85.03 % (5782) 85.24 % (2898) 84.82 % (2884)  
  Drinker 15.23 % (1720) 15.23 % (1141) 15.24 % (579)   14.97 % (1018) 14.76 % (502) 15.18 % (516)  
 Educational level     0.235     0.672
  No formal education/primary 60.23 % (6802) 59.84 % (4484) 61.00 % (2318)   61.04 % (4151) 61.29 % (2084) 60.79 % (2067)  
  Secondary/tertiary 39.77 % (4491) 40.16 % (3009) 39.00 % (1482)   38.96 % (2649) 38.71 % (1316) 39.21 % (1333)  
Clinical parameters (Mean ± SD)
 HbA1c, % 6.83 ± 0.96 (11,293) 6.99 ± 1.05 (7493) 6.52 ± 0.64 (3800) <0.001* 6.57 ± 0.64 (6800) 6.57 ± 0.67 (3400) 6.58 ± 0.62 (3400) 0.351
 SBP, mmHg 133.17 ± 16.91 (11,293) 132.92 ± 17.02 (7493) 133.67 ± 16.69 (3800) 0.026* 133.41 ± 16.77 (6800) 133.28 ± 16.92 (3400) 133.54 ± 16.62 (3400) 0.512
 DBP, mmHg 74.94 ± 10.04 (11,293) 74.98 ± 10.08 (7493) 74.84 ± 9.98 (3800) 0.479 74.75 ± 9.97 (6800) 74.68 ± 10.00 (3400) 74.83 ± 9.95 (3400) 0.530
 LDL-C, mmol/L 3.25 ± 0.84 (11,293) 3.18 ± 0.82 (7493) 3.40 ± 0.87 (3800) <0.001* 3.34 ± 0.84 (6800) 3.32 ± 0.83 (3400) 3.35 ± 0.85 (3400) 0.106
 TC/HDL-C Ratio 4.36 ± 1.26 (11,293) 4.31 ± 1.13 (7493) 4.45 ± 1.46 (3800) <0.001* 4.39 ± 1.16 (6800) 4.38 ± 1.13 (3400) 4.41 ± 1.18 (3400) 0.327
 Triglyceride, mmol/L 1.65 ± 0.89 (11,293) 1.68 ± 0.91 (7493) 1.59 ± 0.85 (3800) <0.001* 1.60 ± 0.83 (6800) 1.60 ± 0.78 (3400) 1.60 ± 0.87 (3400) 0.914
 BMI, kg/m2 25.63 ± 3.91 (11,293) 25.69 ± 3.89 (7493) 25.51 ± 3.94 (3800) 0.018* 25.59 ± 3.85 (6800) 25.56 ± 3.72 (3400) 25.61 ± 3.98 (3400) 0.665
 Stage of CKD (%, n)     <0.001*     0.711
  Stage 1 35.74 % (4036) 37.89 % (2839) 31.50 % (1197)   32.85 % (2234) 32.62 % (1109) 33.09 % (1125)  
  Stage 2 55.98 % (6322) 54.16 % (4058) 59.58 % (2264)   58.71 % (3992) 59.15 % (2011) 58.26 % (1981)  
  Stage 3 8.28 % (935) 7.95 % (596) 8.92 % (339)   8.44 % (574) 8.24 % (280) 8.65 % (294)  
Disease characteristics (%, n)
 Duration of DM     <0.001*     0.652
  <5 years 63.91 % (7217) 59.72 % (4475) 72.16 % (2742)   70.03 % (4762) 70.06 % (2382) 70.00 % (2380)  
  5–10 years 23.84 % (2692) 26.37 % (1976) 18.84 % (716)   20.50 % (1394) 20.76 % (706) 20.24 % (688)  
  >10 years 12.26 % (1384) 13.91 % (1042) 9.00 % (342)   9.47 % (644) 9.18 % (312) 9.76 % (332)  
 Hypertension     <0.001*     0.669
  No 28.30 % (3196) 31.59 % (2367) 21.82 % (829)   23.81 % (1619) 24.03 % (817) 23.59 % (802)  
  Yes 71.70 % (8097) 68.41 % (5126) 78.18 % (2971)   76.19 % (5181) 75.97 % (2583) 76.41 % (2598)  
Treatment modalities (%, n)
 Use of anti-hypertensive drugs     <0.001*     0.956
  No 29.33 % (3312) 31.06 % (2327) 25.92 % (985)   26.41 % (1796) 26.38 % (897) 26.44 % (899)  
  Yes 70.67 % (7981) 68.94 % (5166) 74.08 % (2815)   73.59 % (5004) 73.62 % (2503) 73.56 % (2501)  
 Use of lipid-lowering agents     0.032*     0.699
  No 95.71 % (10809) 95.42 % (7150) 96.29 % (3659)   96.32 % (6550) 96.41 % (3278) 96.24 % (3272)  
  Yes 4.29 % (484) 4.58 % (343) 3.71 % (141)   3.68 % (250) 3.59 % (122) 3.76 % (128)  
  1. MM metformin monotherapy, HbA1c haemoglobin A1c, SBP systolic blood pressure, DBP diastolic blood pressure, LDL-C low density lipoprotein—cholesterol, TC Total cholesterol, HDL-C high density lipoprotein-cholesterol, BMI body mass index, eGFR estimated glomerular filtration rate, DM diabetes mellitus, CKD chronic kidney disease
  2. Stage 1 CKD (eGFR ≥90 ml/min/1.73 m2); Stage 2 CKD (eGFR ≥60 & <90 ml/min/1.73 m2); Stage 3 CKD (eGFR ≥30 & <60 ml/min/1.73 m2)
  3. * Significant with p value < 0.05 by Chi-square test or t test as appropriate