Saturday, June 30, 2007

Systemic inflammation may underlie poor lung function link with CVD

Systemic inflammation may underlie poor lung function link with CVD

Thorax 2007; Advance online publication

MedWire News:

The link between poor lung function and cardiovascular disease (CVD) may be mediated by an inflammatory mechanism, says an international team of researchers.

The team identified an association between lung volumes and serum C-reactive protein (CRP) levels in young adults, which was of similar strength in men and women and was independent of smoking, asthma, and body mass index.

"Impaired lung function not only leads to increased respiratory mortality, but is also associated with adverse cardiovascular events, including myocardial infarction, stroke, and cardiovascular death," write Robert Hancox (University of Otago, Dunedin, New Zealand) and colleagues.

Furthermore, some studies have shown a reduction in the lung function measure forced expiratory volume in 1 second (FEV1) is a stronger indicator of cardiovascular risk than are traditional measures such as cholesterol levels, they add.

To investigate the extent to which this link is mediated by smoking, chronic airway disease, and/or established atherosclerosis, the researchers studied associations between spirometric lung function measures and serum CRP levels in a population-based birth cohort of around 1000 New Zealanders at ages 26 and 32 years.

The mean FEV1 was significantly lower at age 32 years than age 26 years (p=0.0003), and the fall in FEV1 between the two ages was greater for men (0.22 liters) than for women (0.05 liters; p<0.0001).

Analysis of CRP levels categorized as low, medium, and high according to American Heart Association guidelines showed that increasing CRP was associated with decreasing percentage of predicted FEV1 at both ages in women and at 32 years in men (p<0.01).

Further analysis showed that FEV1 values were inversely associated with log-CRP levels at both age 26 and 32 years after adjusting for gender, height, body mass index, smoking, and asthma (both p<0.001).

Associations between lung function and CRP were not significantly different between women and men or between Maori and non-Maori individuals, the team notes.

Finally, the decrease in FEV1 between age 26 and 32 years was a significant predictor of log-CRP at age 32 years, and this longitudinal association was of similar magnitude in men and women.

The authors conclude in the journal Thorax: "While the underlying reason for this association is uncertain, the findings suggest a plausible mechanism by which a reduced FEV1 is associated with an increased risk of CVD in a manner that is independent of smoking and known respiratory disease."