Stephen Thornton's acerbic response in HSJ in September to my concerns about the patient safety industry engenders even greater concerns about this policy area, writes Alan Maynard

First, I would like to emphasise that patient safety is an essential part of healthcare delivery. Furthermore, I welcome strongly the efforts of the last decade to measure errors more systematically and to improve consumer protection. In York Hospital, where I have been chair for nearly 10 years, I have pressed hard to improve hygiene and manage errors better.

However, my concern is to identify cost-effective means of improving patient safety. It is this to which the Institute for Healthcare Improvement and the Health Foundation have paid insufficient attention.

The first part of such work has to identify the clinical effectiveness of the programmes. The Health Foundation has commissioned research to compare a control group with the experimental group to identify the effects of their investment on medical error rates as measured in case records.

So far, so good! However, measuring effect is a wholly inadequate basis on which to base investment decisions. As agreed for many years, what is clinically effective may not be cost-effective and what is cost-effective is always clinically effective. This maxim is the basis of the health technology work of the National Institute for Health and Clinical Excellence.

The Health Foundation's failure to adopt this approach may mean the results of their evaluation will be of limited value. It is remarkable that the research they have commissioned has no economic component. It may identify effect but fail to inform decision-makers whether these effects can be purchased at a reasonable cost.

A likely effect of current Health Foundation investment is to precipitate increased local NHS investment in safety, if only to manage the funding. This effect is likely to be heterogeneous and is not being costed in the existing research protocol. How can the effects of the Health Foundation and the NHS investments be separated?

Mr Thornton wants to identify whether the Health Foundation investment in patient safety is efficient. He has to persuade the NHS that investment in patient safety gives at least as good a return as, for instance, implementing NICE technology appraisals. He will not have the data to do this as things stand at present as he has commissioned an incomplete evaluation of the large investment of the Health Foundation.

Enthusiasm is no substitute for evidence. It wastes scarce resources and damages the interests of patients and taxpayers. I am very anxious to improve patient safety even more in my hospital. However, I also want investment that is informed by robust evidence of cost-effectiveness. I am disappointed that the Health Foundation's work may not provide this evidence.

Professor Alan Maynard, Department of Health Sciences, York University

To read Stephen Thornton and Don Berwick's letter, click here