The effects of COPD are not restricted to the lungs; evidence of persistent systemic inflammation has been assessed by measuring white blood count, C-reactive protein, interleukins 6 and 8 or TNF-α in serum [8, 22]; 16% of COPD patients in the ECLIPSE cohort were shown to have markers of systemic inflammation present [23, 24]. Here, TNF is linked to chronic obstructive pulmonary disease.