Author's response

We welcome the letter by Paul Driscoll and were disappointed, yet not surprised to read of the increased number of consultations, hospital appointments and increased distress to patients, families and carers as a result of urgent facsimile advice to change prescribing practice. We would encourage both the primary care profession and the prescribing regulatory authorities to learn from this episode, and agree with Driscoll that clear guidance should suggest appropriate alternatives with the appropriate supporting evidence.

Regarding the letter by Wilcock, we always suspected that although only claiming generalisability of our findings to the Leeds area, that the picture we described would be representative of the national picture. Despite the obvious attractions of the interocular test, which are obviously in the eye of the beholder (excuse the pun), we felt it important to apply scientific and research methodological rigour to our study. Whereas Wilcock has given us some excellent descriptive data (and we do hope that the BJGP affords him space of a whole figure for a small letter) we do prefer to use comparative statistics wherever possible. Such statistics in the form of a time series analysis can account for any natural seasonal variation which can be missed by the interocular method. Comparative statistics are also both more sensitive and specific to detect small yet significant changes. Such changes can be missed by the naked eye. However, on this topic we feel that the most important point is that there is no evidence that thioridazine is more cardiotoxic than any other anti-psychotic medication. The current evidence base would suggest that all antipsychotic medication should be prescribed with caution to the elderly and those with pre-existing heart disease or those with behavioural disturbance where there could be a tendency or iatrogenic overdose in an over enthusiastic attempt to control behaviour.

• © British Journal of General Practice, 2004.