Use of antibiotic prophylaxis in clean non-implant wounds

J Antimicrob Chemother 1999; 43: 423

M. J. Kelly

Department of General Surgery, Leicester General Hospital NHS Trust, Gwendolen Road, Leicester LE5 4PW, UK

Sir,

I enjoyed reading the leading article by David Leaper entitled `Use of antibioticprophylaxis in clean non-implant wounds'. 1 One message in particular needs to be written across the hearts and minds of all surgicalspecialist registrars desperate for research papers, as well as their consultant chiefs. It is thattwo-armed controlled trials which predict reductions in wound infection rates from 7.5% to 2.5%with a power of 80% require a total of approximately 1600 patients. Trials enrolling smallernumbers are at risk from a type II error, which means that the P value can falsely indicate non-significance at the conventional 5% level when there is actually agenuine underlying benefit from prophylaxis. We have previously expounded this point in detailin the surgical literature. 2

Put simply, the harsh message is that a trial of 200 elective inguinal hernia cases, howevermeticulously carried out, is unlikely to demonstrate a genuine difference in any conceivablerange of infection rates. Consequently, such trials should not be undertaken in the first placeand, in the event that they are, the reports on which they are based should not be accepted forpublication.

Notes

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References

1 . Leaper, D. J. (1998). Use of antibiotic prophylaxis in clean non-implant wounds. Journal of Antimicrobial Chemotherapy 41, 501–4.[Free Full Text]

2 . Kelly, M. J. & Wadsworth, J. (1993). What price inconclusive clinical trials? Annals of the Royal College of Surgeons of England 75, 145–6.[ISI][Medline]