Table I.
Descriptive characteristics of participants across quartiles of caffeine
| Characteristics | Quartiles of caffeine | P-value | |||
|---|---|---|---|---|---|
| First | Second | Third | Fourth | ||
| Median (25th–75th) [mg] | 11 (7–19) | 51 (34–72) | 142 (112–171) | 329 (260–462) | |
| Number of participants | 4609 | 4611 | 4608 | 4608 | |
| Gender (%): | < 0.001 | ||||
| Male | 43.8 | 44.7 | 48.9 | 57.5 | |
| Female | 56.2 | 55.3 | 51.1 | 42.5 | |
| Age [years] | 44.2 ±0.3 | 45.6 ±0.3 | 47.4 ±0.2 | 50.1 ±0.2 | < 0.001 |
| Race (%): | < 0.001 | ||||
| White (non-Hispanic) | 32.8 | 36.7 | 49.3 | 70.0 | |
| Non-Hispanic Black | 20.7 | 24.5 | 19.5 | 11.7 | |
| Mexican-American | 33.3 | 23.9 | 17.2 | 9.1 | |
| Income to poverty (n) | 2.3 ±0.02 | 2.3 ±0.02 | 2.5 ±0.02 | 2.8 ±0.02 | < 0.001 |
| BMI [kg/m2] | 28.8 ±0.1 | 28.6 ±0.1 | 28.9 ±0.1 | 28.8 ±0.1 | 0.253 |
| Energy intake [kcal/day] | 1970.2 ±14.2 | 2053.2 ±15.3 | 2086.7 ±14.2 | 2339.2 ±15.9 | < 0.001 |
| Alcohol intake [g/day] | 9.5 ±0.4 | 8.9 ±0.3 | 9.6 ±0.5 | 12.1 ±0.4 | < 0.001 |
| Triglyceride [mg/dl] | 144.3 ±1.9 | 145.5 ±2.0 | 157.4 ±1.8 | 160.2 ±2.3 | < 0.001 |
| Type 2 diabetes (%) | 17.9 | 18.4 | 19.1 | 17.0 | < 0.001 |
| Hypertension (%) | 10.9 | 10.1 | 10.5 | 11.3 | < 0.001 |
| Low eGFR (%) | 9.4 | 7.8 | 5.8 | 5.2 | < 0.001 |
| Albuminuria (%) | 9.8 | 10.1 | 11.5 | 9.7 | < 0.001 |
| CKD (%) [low eGFR or albuminuria] | 16.6 | 13.9 | 12.2 | 11.0 | < 0.001 |
Value expressed as mean and S.E.M. or percentage. CKD – chronic kidney disease, eGFR – estimated glomerular filtration rate.