C-reactive protein (CRP) is considered one of the key markers of systemic inflammation in chronic obstructive pulmonary disease (COPD) and currently receives a lot of attention. In their systematic review of systemic inflammation in COPD, Gan et al showed that CRP was associated with the level of forced expiratory volume in 1 s (FEV₁) in the five studies included in the review,¹ and two recent studies using fairly large populations of well-characterised patients with COPD have shown a strong association between increased CRP levels and prognosis.^2,3 Sin and Man have previously shown that raised levels of CRP were associated with cardiac injury in COPD⁴ but, in the two recent studies, the association between CRP and mortality was not merely driven by an associated risk of cardiovascular deaths.^2,3

In this issue of Thorax (see p 515) Fogarty et al examine the association between CRP and FEV₁ in more detail.⁵ Using data on 2633 randomly selected adults …