Highly elevated C-reactive protein levels in obese patients with COPD: a fat chance?

Chronic obstructive pulmonary disease (COPD) has been recognized as a multi component disease. Currently, limited data are available about determining factors of systemic inflammation in COPD, in particular C-reactive protein (CRP). The aim was to determine whether and to what extent COPD patients with a low, high or obese body mass index (BMI) are more likely to have elevated CRP levels compared to normal-weight COPD patients. Furthermore, we aimed to explore the effects of clinically relevant covariates on the likelihood of having elevated CRP levels.

In 628 elderly patients with moderate to severe COPD (61% male), lung function and BMI were assessed before entering pulmonary rehabilitation. In addition, blood was collected in the fasted state. High-sensitive C-reactive protein (CRP) was classified into: normal, < or =3; elevated, >3-5 and highly elevated, >5mg/l.

Obese COPD patients (BMI> or =30 kg/m(2)) were 3.3 times more likely (95% CI, 1.5-7.0, p=0.002) to have highly elevated CRP levels compared to normal weight (BMI 21-24.9 kg/m(2)) COPD patients after taking clinically relevant confounders into account. In contrast, COPD patients with a low BMI (<21 kg/m(2)) were 2 times less likely (OR, 0.5; 95% CI, 0.3-0.9, p=0.022) to have highly elevated CRP levels compared to normal-weight peers.

Obese BMI is associated with highly elevated CRP levels in patients with COPD. These findings are suggestive for an adipocyte-induced systemic inflammation in COPD.