Identifying patients with ischaemic heart disease in general practice: cross sectional study of paper and computerised medical records

An error in a formula appeared in the appendix to this paper by Jeremy Gray and colleagues (2 September, pp 548-50). The appendix appears only on the BMJ's website, at http://bmj.com/cgi/content/full/321/7260/548/DC1. The formula given in the second paragraph should read: “100 000×0.39×0.087×0.96×1/0.45 [not 100/0.45]=7166.”