Table 1.
Characteristics of the study sample of black South Africans and a comparison between sexes.
| Study sample | Main genetic association study sample | ||||
|---|---|---|---|---|---|
| N | All | Men | Women | p | |
| Age (years) | 4,431 | 52 (46–58) | 52 (46–58) | 52 (46–58) | 0.185 |
| BMI (kg/m2) | 4,147 | 27.2 (22.2–32.7) | 23.2 (20.1–27.4) | 30.5 (25.8–35.5) | <0.001 |
| Waist circumference (cm) | 4,148 | 95.8 (89.4–101.5) | 88.0 (78.0–89.8) | 98.0 (92.3–103.2) | <0.001 |
| Systolic blood pressure (mmHg) | 3,496 | 128.5 (116.0–144.0) | 129.0 (116.5–144.0) | 128.0 (115.5–144.0) | 0.424 |
| Diastolic blood pressure (mmHg) | 3,499 | 83.0 (74.5–91.5) | 84.0 (75.0–92.5) | 82.5 (74.0–91.5) | 0.027 |
| Fasting glucose (mmol/L) | 3,406 | 4.9 (4.6–5.4) | 4.8 (4.4–5.3) | 5.0 (4.6–5.5) | <0.001 |
| Fasting insulin (uIU/ml) | 3,417 | 7.2 (4.3–13.1) | 7.0 (4.3–13.3) | 7.4 (4.3–12.9) | 0.327 |
| HOMA-IR | 2,985 | 1.6 (0.9–3.1) | 1.6 (0.9–3.2) | 1.7 (0.9–3.0) | 0.768 |
| Total cholesterol (mmol/L) | 4,345 | 4.1 (3.5–4.9) | 4.0 (3.3–4.7) | 4.3 (3.6–5.0) | <0.001 |
| LDL cholesterol (mmol/L) | 4,309 | 2.5 (1.9–3.1) | 2.3 (1.8–2.9) | 2.6 (2.0–3.2) | <0.001 |
| HDL cholesterol (mmol/L) | 4,347 | 1.2 (1.0–1.4) | 1.1 (0.9–1.4) | 1.2 (1.0–1.4) | 0.111 |
| Triglycerides (mmol/L) | 4,344 | 0.9 (0.7–1.3) | 0.9 (0.6–1.3) | 0.9 (0.7–1.3) | 0.003 |
| Blood pressure med [n/N (%)] | 3,450 | 991/3,450 (28.7) | 329/1,350 (24.3) | 662/2,100 (31.5) | 0.869 |
| Diabetes med [n/N (%)] | 3,450 | 366/3,450 (10.6) | 134/1,362 (9.8) | 232/2,088 (11.1) | 0.259 |
| Cholesterol med [n/N (%)] | 2030 | 8/2,030 (0.4) | 2/1,337 (0.1) | 6/693 (0.9) | 0.211 |
| Smoking [n/N (%)] | 3,108 | 597/3,108 (19.2) | 538/1,078 (49.9) | 59/2,030 (2.9) | <0.001 |
| Alcohol [n/N (%)] | 2,502 | 1,292/2,502 (51.6) | 954/1,168 (81.7) | 338/1,334 (25.3) | <0.001 |
| *Corticosterone (nmol/L) | 650 | 6.0 (3.5–12.2) | 5.0 (3.4–8.8) | 6.4 (3.6–14.6) | 0.003 |
| *Cortisol (nmol/L) | 673 | 183.3 (96.6–322.6) | 143.0 (74.1–295.7) | 208.3 (84.2–343.8) | 0.003 |
| *Corticosterone/cortisol | 548 | 0.05 (0.02–0.09) | 0.04 (0.02–0.07) | 0.05 (0.02–0.09) | 0.050 |
Continuous data presented as median (IQR, interquartile range) and categorical data presented as number of prevalent/total number of observations (n/N) and percentage (%). Wilcoxon Rank Sum and Chi-square test were used to statistically compare the continuous and categorical variables, respectively, between the sex groups. p, value of p for the statistical difference between men and women; BMI, body mass index; HOMA-IR, homeostatic model assessment of insulin resistance; LDL, low density lipoprotein; HDL, high density lipoprotein; and Med, medication. All medication and lifestyle factors (smoking and alcohol) were self-reported during interview sessions.
Measured in the Soweto sub-sample.