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I commend the author for comprehensively investigating a complex area but found some important pieces of information missing in the study.1 Firstly, there is no information regarding the total number of patients seen in the accident and emergency (A&E) department during the study period. This information would put into better perspective the number of patients (934) who had recorded diagnostic errors and would allow for more scientifically valid comparison of the findings of this study by other A&E departments. Secondly, there is no record of the number of cases where there was dispute over the diagnosis between A&E clinician and radiologist. Furthermore, it seems the author alone made the final decision regarding the diagnosis in such cases. This is a very subjective method of diagnosis with little scientific validity. Moreover, there is no information as to the specific diagnosis made and subsequent management of this group of patients. The management of this subset of cases is a dilemma for A&E clinicians and more information from the author on their management will be informative. Finally, hospital policy for reporting A&E radiographs changed during the study period. Did this have any effect on the number of diagnostic errors recorded? Data comparing the number of diagnostic errors before and after the change of policy to immediate reporting of radiographs would provide useful scientific evidence for radiologists to decide whether to give priority to A&E radiographs.
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Author's reply
I thank Dr Wakai for his comments. The total number of new patients seen over the four year period in which this study took place was 244 442. I have no record of the number of cases where there was dispute over the diagnosis between A&E clinician and radiologist, but the number was very small, and usually related to a radiology trainee, rather than a consultant radiologist. The subsequent management of patients in whom diagnostic errors had been made was left to the individual consultant and I have no specific data on this but it obviously varied with the severity of the diagnostic error and the circumstances in which the error was discovered. Clearly, if the diagnostic error was discovered when the patient reattended the A&E department, or a follow up clinic, it was dealt with there and then, but if an error was discovered by a radiological report, probably most patients were sent an appointment to reattend one of the A&E clinics, though some patients would have been telephoned and asked to return immediately. For very minor errors, for example, minor avulsion fractures, the GP would have been informed that the patient would not have been advised to return.
The change in radiological reporting that occurred part of the way through the study was, of course, only one change that occurred over the four year period. There were also changes in staffing and as the idea behind the original collection of data was for continual quality improvement, the results of the study each six months led to changes in teaching, etc. For what it is worth, the incidence of diagnostic errors appeared to fall for the 12 months after the introduction of hot reporting, but subsequently rose again. It is difficult to attribute this completely to the change in radiological reporting. In addition, as the study notes, it proved very difficult to obtain details of every diagnostic error and the data are certainly incomplete. I am not sure that conclusions on the effectiveness of changing the radiological reporting system based on incomplete data would be scientifically valid.
Dr Wakai rightly states that diagnosis based on the opinion of a single person is not valid. To this must be added the difficulties in defining diagnostic error and the incompleteness of the data.
With a relatively low incidence of diagnostic errors, a study to accurately determine the incidence of these and to draw scientifically valid conclusions about their types, causes, etc, would require 100% follow up of many thousands of patients with all potential diagnostic errors being submitted to a panel to determine the exact diagnosis. Such a study would be very expensive and has never been done.
My study was, I hope, more than just “one consultant's experience of diagnostic errors he has encountered”, as I actively tried to seek out all diagnostic errors as part of a quality improvement exercise. It must be regarded as a best attempt at determining all diagnostic errors for audit purposes but with no additional resources allocated. As such, I hope that it will be useful when discussing quality of service in A&E departments, but it did not accurately define every diagnostic error that occurred over the four year period.