Baseline and follow-up characteristics of the study participants by baseline B12 quartiles
| Variables | Total | Baseline vitamin B12 quartiles (pmol/L) | P value | |||
| Q1 (<232.3) | Q2 (232.3–279.4) | Q3 (279.4–349.8) | Q4 (≥349.8) | |||
| n | 16 699 | 4175 | 4173 | 4176 | 4175 | |
| Age (years) | 60.0 (7.4) | 60.4 (7.4) | 60.1 (7.5) | 59.7 (7.4) | 59.9 (7.3) | <0.001 |
| Male | 6713 (40.2%) | 1833 (43.9%) | 1632 (39.1%) | 1661 (39.8%) | 1587 (38.0%) | <0.001 |
| BMI (kg/m2) | 25.0 (3.7) | 24.9 (3.6) | 25.2 (3.7) | 25.2 (3.7) | 24.8 (3.6) | <0.001 |
| Total cholesterol (mmol/L) | 5.5 (1.2) | 5.3 (1.1) | 5.5 (1.2) | 5.6 (1.2) | 5.7 (1.3) | <0.001 |
| Triglycerides (mmol/L) | 1.7 (1.2) | 1.6 (0.9) | 1.6 (0.9) | 1.7 (1.0) | 1.7 (1.8) | <0.001 |
| HDL-C (mmol/L) | 1.3 (0.4) | 1.3 (0.3) | 1.3 (0.4) | 1.3 (0.4) | 1.4 (0.4) | <0.001 |
| ALT (U/L) | 49.1 (5.8) | 48.3 (5.6) | 49.1 (5.8) | 49.6 (5.8) | 49.5 (5.8) | <0.001 |
| AST (U/L) | 26.1 (36.5) | 24.8 (9) | 24.6 (9.1) | 25.9 (11.1) | 29.2 (70.8) | <0.001 |
| FBG (mmol/L) | 5.8 (1.7) | 5.6 (1.3) | 5.8 (1.5) | 5.9 (1.7) | 6.0 (2.1) | <0.001 |
| Exit FBG (mmol/L) | 6.3 (2.0) | 6.1 (1.7) | 6.2 (2.0) | 6.3 (2.1) | 6.4 (2.2) | <0.001 |
| Folate (ng/mL) | 8.0 (5.6–10.4) | 7.5 (5.2–9.9) | 7.7 (5.4–10) | 8.1 (5.7–10.4) | 8.7 (6.1–11.1) | <0.001 |
| B12 (pmol/L) | 277.8 (231.7–345.7) | 205.7 (184.7–219.8) | 254.8 (243.8–266.6) | 308.7 (292.6–327.5) | 409.5 (375.6–460.2) | <0.001 |
| Homocysteine (μmol/L) | 12.5 (10.4–15.4) | 13.8 (11.3–17.5) | 12.7 (10.6–15.9) | 12.1 (10.3–14.6) | 11.6 (9.8–13.9) | <0.001 |
| eGFR (mL/min per 1.73 m2) | 93.6 (13.0) | 93.8 (12.5) | 93.6 (13.0) | 94.0 (12.7) | 92.8 (13.6) | <0.001 |
| SBP (mm Hg) | 167.2 (20.4) | 165.7 (20.1) | 167.4 (20.4) | 168.4 (20.8) | 167.4 (20.3) | <0.001 |
| DBP (mm Hg) | 94.2 (11.9) | 93.2 (12.0) | 94.2 (11.8) | 94.8 (11.8) | 94.4 (11.9) | <0.001 |
| Mean SBP during the treatment period (mm Hg) | 139.0 (10.6) | 139.1 (10.8) | 139.0 (10.5) | 138.9 (10.4) | 138.8 (10.5) | 0.641 |
| Mean DBP during the treatment period (mm Hg) | 82.8 (7.2) | 82.6 (7.4) | 82.8 (7.3) | 83.0 (7.1) | 82.7 (7.1) | 0.058 |
| MTHFR C677T | <0.001 | |||||
| CC | 4529 (27.1%) | 1047 (25.1%) | 1060 (25.4%) | 1163 (27.8%) | 1259 (30.2%) | |
| CT | 8185 (49.0%) | 1962 (47.0%) | 2015 (48.3%) | 2121 (50.8%) | 2087 (50.0%) | |
| TT | 3985 (23.9%) | 1166 (27.9%) | 1098 (26.3%) | 892 (21.4%) | 829 (19.9%) | |
| Treatment group | 0.814 | |||||
| Enalapril | 8369 (50.1%) | 2076 (49.7%) | 2098 (50.3%) | 2080 (49.8%) | 2115 (50.7%) | |
| Enalapril-folic acid | 8330 (49.9%) | 2099 (50.3%) | 2075 (49.7%) | 2096 (50.2%) | 2060 (49.3%) | |
| Center | <0.001 | |||||
| Anqing | 3905 (23.4%) | 869 (20.8%) | 712 (17.1%) | 946 (22.7%) | 1378 (33.0%) | |
| Lianyungang | 12 794 (76.6%) | 3306 (79.2%) | 3461 (82.9%) | 3230 (77.3%) | 2797 (67.0%) | |
| Smoking status | <0.001 | |||||
| Never | 11 613 (69.6%) | 2778 (66.6%) | 2941 (70.5%) | 2917 (69.9%) | 2977 (71.3%) | |
| Former | 1259 (7.5%) | 322 (7.7%) | 271 (6.5%) | 313 (7.5%) | 353 (8.5%) | |
| Current | 3820 (22.9%) | 1072 (25.7%) | 960 (23.0%) | 945 (22.6%) | 843 (20.2%) | |
| Alcohol drinking | 0.334 | |||||
| Never | 11 596 (69.5%) | 2858 (68.5%) | 2959 (70.9%) | 2878 (68.9%) | 2901 (69.5%) | |
| Former | 1145 (6.9%) | 290 (7.0%) | 279 (6.7%) | 292 (7.0%) | 284 (6.8%) | |
| Current | 3947 (23.7%) | 1022 (24.5%) | 933 (22.4%) | 1005 (24.1%) | 987 (23.7%) | |
| Meat consumption | <0.001 | |||||
| Never | 10 468 (63.3%) | 2788 (68.0%) | 2671 (64.6%) | 2562 (61.7%) | 2447 (59.1%) | |
| 1–2 times per week | 4642 (28.1%) | 1069 (26.1%) | 1131 (27.4%) | 1186 (28.6%) | 1256 (30.3%) | |
| 3–5 times per week | 978 (5.9%) | 173 (4.2%) | 227 (5.5%) | 292 (7.0%) | 286 (6.9%) | |
| Every day | 442 (2.7%) | 71 (1.7%) | 106 (2.6%) | 112 (2.7%) | 153 (3.7%) | |
| Medication use | ||||||
| Antidiabetic drugs | 260 (1.6%) | 33 (0.8%) | 46 (1.1%) | 73 (1.7%) | 108 (2.6)% | <0.001 |
| Lipid-lowering drugs | 141 (0.8%) | 32 (0.8%) | 36 (0.9%) | 32 (0.8%) | 41 (1%) | 0.667 |
| Antihypertensive drugs | 7813 (46.8%) | 1921 (46%) | 1956 (46.9%) | 1943 (46.5%) | 1993 (47.7%) | 0.45 |
Data are n (%), mean (SD), and median (IQR).
The significance of differences in population characteristics between groups was computed using signed-rank tests, or χ2 tests, for continuous and categorical variables.
ALT, alanine aminotransferase; AST, aspartate aminotransferase; BMI, body mass index; DBP, diastolic blood pressure; eGFR, estimated glomerular filtration rate; FBG, fasting blood glucose; HDL-C, high-density lipoprotein cholesterol; MTHFR, methylenetetrahydrofolate reductase; SBP, systolic blood pressure.