Calderón-Larrañaga A, Carney L, Soljak M, et al. Association of population and primary healthcare factors with hospital admission rates for chronic obstructive pulmonary disease in England: national cross-sectional study. Thorax 2011;66:191–96.

We wish to report a single error in our paper on associations of population and primary healthcare factors with hospital admission rates for chronic obstructive pulmonary disease. An observant researcher has questioned an R squared value for a univariate analysis at primary care trust level. In our paper we reported that about 14.4% of the variance in hospital admissions was explained by GP supply. We have re-run the analyses and confirm that there was a typographical error on our part. The R squared value of 14.4% was actually for the variable GP list size and not for GP supply (the latter has a R squared of 0.1%). The rest of the values are correct. We consider that this correction has no effect on the overall conclusions of our paper, as the important findings were at general practice level.