Table 1. Baseline characteristics of participants according to quartiles of serum small dense low-density lipoprotein cholesterol levels (the Hisayama Study, 2007–2008).
| Serum sdLDL cholesterol level, mg/dL | |||||
|---|---|---|---|---|---|
| Variables | Quartile 1 | Quartile 2 | Quartile 3 | Quartile 4 | p for trend |
| ≤ 24.4 | 24.5–32.8 | 32.9–43.6 | ≥ 43.7 | ||
| (n = 763) | (n = 775) | (n = 768) | (n = 774) | ||
| Age (years) | 65 (15) | 63 (12) | 64 (11) | 61 (10) | < 0.001 |
| Men (%) | 35.0 | 38.3 | 42.1 | 52.1 | < 0.001 |
| Systolic blood pressure (mmHg) | 127 (20) | 129 (19) | 134 (19) | 136 (18) | < 0.001 |
| Use of antihypertensive agents (%) | 30.9 | 27.6 | 31.6 | 27.9 | 0.49 |
| HbA1c (%) | 5.3 (0.7) | 5.5 (0.7) | 5.5 (0.8) | 5.7 (0.9) | < 0.001 |
| Use of glucose-lowering agents (%) | 5.1 | 6.8 | 6.9 | 7.1 | 0.14 |
| HOMA-IR | 1.1 (0.7–1.5) | 1.2 (0.8–1.8) | 1.4 (0.9–2.1) | 1.8 (1.2–2.7) | < 0.001 |
| Serum total cholesterol (mg/dL) | 179.7 (26.6) | 204.7 (25.5) | 216.8 (30.9) | 237.2 (34.2) | < 0.001 |
| Serum LDL cholesterol (mg/dL) | 92.4 (19.4) | 116.2 (20.3) | 131.1 (24.5) | 148.3 (31.0) | < 0.001 |
| Serum HDL cholesterol (mg/dL) | 72.9 (18.2) | 71.6 (18.0) | 65.7 (17.0) | 58.8 (15.0) | < 0.001 |
| Serum triglycerides (mg/dL) | 71 (55–92) | 89 (68–115) | 107 (83–139) | 163 (120–232) | < 0.001 |
| Use of lipid-modifying agents (%) | 16.1 | 12.9 | 14.5 | 12.1 | 0.064 |
| Use of statins (%) | 15.7 | 12.9 | 13.8 | 10.3 | 0.005 |
| BMI (kg/m2) | 21.9 (3.5) | 22.3 (3.1) | 23.5 (3.5) | 24.3 (3.3) | < 0.001 |
| eGFR (ml/min/1.73 m2) | 73.5 (14.9) | 75.5 (12.4) | 75.0 (11.7) | 77.1 (11.1) | < 0.001 |
| Electrocardiogram abnormalities (%) | 16.4 | 12.9 | 15.8 | 16.3 | 0.65 |
| Serum hs-CRP (mg/L) | 0.3 (0.1–0.7) | 0.4 (0.2–0.7) | 0.4 (0.2–0.8) | 0.6 (0.3–1.0) | < 0.001 |
| Current smoking (%) | 15.1 | 18.5 | 19.4 | 26.7 | < 0.001 |
| Current drinking (%) | 39.7 | 45.4 | 47.5 | 57.8 | < 0.001 |
| Regular exercise (%) | 11.6 | 12.5 | 11.3 | 12.0 | 0.98 |
SI conversion factors: To convert mg/dL values to mmol/L, multiply serum sdLDL cholesterol, serum total cholesterol, serum LDL cholesterol, and HDL cholesterol values by 0.02586, and multiply serum triglycerides values by 0.01129.
Data are presented as the mean values (standard deviation), percentages, or medians (interquartile range).
The trends in the means and the frequencies of risk factors across the quartiles of sdLDL cholesterol were tested by a linear and a logistic regression analysis. Serum HOMA-IR, triglycerides, and hs-CRP levels were log-transformed in the analyses due to skewed distribution.
Abbreviations: BMI, body mass index; eGFR, estimated glomerular filtration rate; HbA1c, hemoglobin A1c; HDL, high-density lipoprotein; HOMA-IR, homeostasis model assessment of insulin resistance; hs-CRP, high-sensitivity C-reactive protein; LDL, low-density lipoprotein; sdLDL, small dense low-density lipoprotein.