Precursors of Essential Hypertension: Pulmonary Function, Heart Rate, Uric Acid, Serum Cholesterol, and Other Serum Chemistries

Exploratory analyses were conducted in a nested case-control study of 1,031 incident cases of essential hypertension and 1,031 persistently normotensive controls from the Kaiser Permanente Multiphasic Health Checkup cohort in Northern California. Previous analyses have confirmed hypotheses that baseline weight, subsequent weight gain, alcohol consumption, parental history of hypertension, excessive use of salt, and centralized body fat distribution are predictive of developing hypertension. In the present study, pulmonary function tests, several serum chemistries, and heart rate were strongly predictive in univariate analyses. Adjusting for the risk factors mentioned above, forced vital capacity (p less than 0.001), serum uric acid (p = 0.003), serum cholesterol (p = 0.012), and heart rate (p = 0.014) remained independently predictive. Further adjustment for baseline blood pressure completely explained the association of heart rate with hypertension, and reduced the association with serum cholesterol to borderline significance. Forced vital capacity remained a strong, inverse predictor (odds ratio, fifth vs. first quintile = 0.22, 95% confidence interval (Cl) 0.11-0.46). Uric acid remained positively related to risk (odds ratio, fifth vs. first quintile = 2.19, 95% Cl 1.20-3.98). Although neither association is presently understood, both forced vital capacity and serum uric acid are closely linked to development of hypertension and may be markers of susceptibility or intermediate steps in pathways leading to hypertension.