To the Editor: I would like to comment on the recent article by Newby et al.1 They conclude that the default settings in computerised prescription packages result in a significant increase in the use of antibiotics. I do not believe this is a valid conclusion.

As the authors state that 85% of general practitioners generating computerised prescriptions are using Medical Director (MD), it is reasonable to assume that the default settings in MD would contribute significantly to this effect if their conclusion is correct.

I have installed and tested MD v.2.3 from February 2000, MDW v.1.85 from February 2000 and MD v.2.4 from May 2000. These were the versions that would have been in use at the time of this study.

All versions default to printing "once-only" prescriptions without repeats. In fact, when a "once-only" prescription has been selected, MD's default behaviour is to display a prompt for the quantity and repeats with the default repeats field set to "0".

This is very easy to verify simply by installing a copy of MD onto a "clean" computer and printing some scripts. As this was evidently not done, it casts doubt on the quality of the whole study. How can the authors reach a conclusion about the effect of the default settings in computerised prescription packages without first ascertaining what those default settings are? They appear to have assumed that the default behaviour of all computer prescription packages is to print the maximum number of repeats allowed by the Pharmaceutical Benefits Scheme. No attempt appears to have been made to verify whether this is the case.

Whatever the reason for the observed increase in repeat antibiotic prescriptions, it is incorrect to conclude that it is due to the default settings in computerised prescribing packages. No discussion of other possible explanations for the observed increase is presented and it appears as though the data have been used to support a conclusion that had been decided before the study was commenced.

In reply: As Pyefinch notes, if the "once only" option in Medical Director (MD) is chosen during prescribing, the doctor must enter the quantity and number of repeats that he or she wishes to order. However, if the doctor chooses the "regular" medicine option (both options are offered during prescribing), then the maximum Pharmaceutical Benefits Schedule quantities and repeats are inserted.

There are various reasons why doctors may be using the "regular" option rather than the "once only" option when prescribing antibiotics using MD. Some of these have been discussed on the General Practice Computing Group Listserv,1 and include factors such as confusion regarding the terms "regular" and "once only" and difficulties recalling patient medication histories if the "once only" option is used. Another explanation is that doctors commonly prescribe chronic medications, and therefore use of the "regular" option may become a habit. Whatever the cause, there is no obvious explanation for the differences observed, except for the use of prescribing software. Our recommendation that prescribing software be altered to avoid these shortcuts was made because it represents the most immediate way of resolving the problem.