Background: Previous studies of western populations have shown an inverse association between lung function and blood pressure.
Methods: As part of a People's Republic of China-United States cardiopulmonary epidemiology study, we investigated the cross-sectional relationship between lung function and blood pressure in 6757 Chinese men and women, aged 35-54, from Beijing and Guangzhou, China. We also evaluated the longitudinal association between lung function and incident hypertension among 4818 initially normotensive subjects followed up between 2 and 4 years later.
Results: In our cross-sectional analyses of baseline data, lung function varied inversely with baseline systolic (SBP) and diastolic blood pressure (DBP) in all women and in Beijing men. This association held for absolute and height-standardized forced vital capacity (FVC) and one-second forced expiratory volume (FEV1) (correlations: 0.10, -0.18, P < 0.0001), but was weaker after adjustment for age (correlations: -0.02, -0.11). The longitudinal follow-up showed that lower initial lung function levels were associated with a higher incidence of hypertension (SBP > or = 140 mmHg or DBP > or = 90 mmHg or currently using antihypertensive medications), but only among women in Guangzhou. Relative risks for hypertension incidence for those in the two lowest quintiles for FEV1 and FVC, compared to those in the two highest quintiles, ranged from 1.9 to 2.3 for Guangzhou women and from 0.9 to 1.4 for all other gender-city subgroups. Logistic regression analyses adjusting for age, baseline SBP, body mass index, smoking, education, and urban versus rural setting generally confirmed these patterns.
Conclusions: These results suggest a statistically significant, though weak, inverse relationship between lung function and blood pressure in Chinese men and women. This association is largely attributable to age and is present prospectively only in women.