Author's reply

EDITOR,--It is inevitable that readers will have found weaknesses in my analysis of prescription data. There is, however, an urgent need to review prescribing in the light of the many published guidelines over the past five years, and it is regrettable that more robust data are not available.

A M Ross and D M Fleming point out that the rate of registration and de-registration of patients within individual practices over one year is up to 30.6%.1 This, however, would make virtually no difference to the analyses. As just under a tenth of patients were being prescribed treatments for asthma in the one year period, this means that only 3% would be added to or subtracted from the total with …