G C Donaldson, T A R Seemungal, A Bhowmik, and J A Wedzicha. Relationship between exacerbation frequency and lung function decline in chronic obstructive pulmonary disease. Thorax 2002;57:847–52.

The legend for fig 2 should read: “Change in FEV₁ with standard errors over 4 years. Open circles represent frequent exacerbators; closed circles represent infrequent exacerbators.”