EDITOR—Our paper comparing the NHS with Kaiser Permanente has generated lively interest and, on the whole, a constructive debate. 1 2 Discerning commentators have noted that further refinement of the data and the analysis (which we strongly advocate) is unlikely to change the basic conclusions. These are that Kaiser Permanente offers improved performance at roughly the same cost and that, therefore, there are probably lessons to be learnt that would benefit the future performance of the NHS. We have further noted from the extensive debate that has followed the publication of …