Hypertension, systemic inflammation and body weight in relation to lung function impairment-an epidemiological study

Abstract

Recent reports on the simultaneous occurrence of systemic inflammation and airflow obstruction are usually based on a highly selective patient population, but their importance warrants further evaluation in the general population. The objectives were to study the interrelationship between airflow obstruction, smoking, hypertension, obesity and CRP as a marker of systemic inflammation in a randomly selected sample of the general Icelandic population (n = 939). This study comprised 758 randomly selected men and women 40 years and older living in Reykjavik, Iceland, and who were participating in the Burden of Obstructive Lung Disease (BOLD) study (81% response rate). In addition to the BOLD protocol, which included post-bronchodilator spirometry, they answered questions about general health and medication. Serum samples were taken for measurement of C-reactive protein (CRP). In the sample-245 individuals (33%) reported having hypertension. Subjects with hypertension were older, had a higher BMI and higher CRP levels. Subjects with hypertension had lower values of FEV(1) than predicted (89.9 +/- 18.5 vs. 94.5 +/- 14.4%) (p < 0.001) and FVC (92.2 +/- 15.1 vs. 95.3 +/- 12.3%) (p = 0.002). These differences remained significant after adjusting for age, BMI, CRP and smoking. Hypertension and CRP levels above the median were both independently and additively associated with lower FEV(1) and FVC. In addition a lower FVC% was also associated with a higher BMI (> 30 mg/m2). Use of betablocking antihypertensives was not related to lung function. Hypertension, BMI and systemic inflammation affect lung function independently of each other. All three variables have a negative effect on FVC, while hypertension and high CRP were independently associated with impaired FEV(1).

Figure 1

Hypertension and impaired lung function (FEV₁ < 80% predicted in different age groups).

Figure 2

Association between lung function and hypertension, obesity (BMI > 30 kg/m²) and high CRP (above median). The associations were adjusted for age, sex, current smoking and pack-years.