Letters (23 September, 7 October) on Neil Pettinger's article ('Richly deserving, page 20-21, 9 September) in favour of positive discrimination for the poor on NHS waiting lists indicate some people took the suggestion seriously.

Such a bias would be wrong for many moral and ethical reasons, but also because of practical difficulties in managing waiting lists. Surgeons trying to make the best use of limited operating theatre time already have to deal with clinical urgency, anaesthetist availability, patient cancellations, training requirements, staff holidays, patient preferences, availability of ward or intensive care beds - and endless other important factors. The addition of what Neil Pettinger suggests would make an almost impossible job even more so.

David L Crosby Hon consultant surgeon University Hospital of Wales