Table 1. Hazard ratios for incident hypertension occurring between year 10 and year 25 according to plasma concentrations of ascorbic acid at year 10: Coronary Artery Risk Development in Young Adults (CARDIA) Study 1 .
| Quartiles of year 10 plasma ascorbic acid | P value for linear trend 2 | Per 19.6 μmol/L increase 3 | ||||
|---|---|---|---|---|---|---|
| 1 (lowest) | 2 | 3 | 4 (highest) | |||
| Plasma ascorbic acid (μmol/L), median (range) | 24.0 (4.5–34.3) | 42.3 (34.4–48.8) | 54.8 (48.9–61.8) | 70.0 (61.9–211.2) | ||
| No. incident cases/N | 274/721 | 225/720 | 188/723 | 153/720 | ||
| Hazard ratio (95% CI): | ||||||
| Model 1 4 | Reference | 0.88 (0.73, 1.05) | 0.74 (0.62, 0.90) | 0.63 (0.51, 0.78) | <0.0001 | 0.86 (0.80, 0.92) |
| Model 2 5 | Reference | 0.87 (0.72, 1.04) | 0.74 (0.60, 0.89) | 0.62 (0.50, 0.77) | <0.0001 | 0.85 (0.79, 0.92) |
| Model 3 6 | Reference | 0.88 (0.74, 1.06) | 0.80 (0.66, 0.98) | 0.72 (0.58, 0.89) | 0.001 | 0.91 (0.84, 0.98) |
Abbreviations: CI, confidence interval.
1 Shown are hazard ratios for incident hypertension according to year 10 (1995–1996) plasma ascorbic acid in 2884 participants without a history of hypertension at year 10.
2 P value for modeling median values for each quartile of plasma ascorbic acid as a continuous variable.
3 Hazard ratio per SD higher plasma ascorbic acid.
4 Adjusted for age (years), sex, race, center, and education (years).
5 Further adjusted for cigarette smoking (dummy variables for current and former cigarette smoking), alcohol intake (ml/day), physical activity score (exercise units), and use of a vitamin supplement (yes/no) (all at year 10).
6 Further adjusted for BMI (kg/m2), waist circumference (cm), history of diabetes, and systolic blood pressure (mmHg) (all at year 10).