Letters

Laterality of lower limb amputation in diabetic patients

Particular attention should be paid to dominant foot at regular review

Study of 15 636 patients found no influence of laterality on risk of amputation

Summary of electronic responses

Particular attention should be paid to dominant foot at regular review

EDITORFoot ulceration affects as many as 15% of patients with diabetes; Mancini and Ruotolo estimated that 6-20% of all patients in hospital with diabetes have foot ulcers.¹ A recent retrospective study of amputations in people with diabetes noted a striking laterality, with nearly all occurring on the right side.² The main predisposing factors to ulceration (peripheral vascular disease, neuropathy, and infection) cannot adequately explain this observation.

We therefore postulated that the excess of right sided amputations in patients with diabetes might be related to right or left sided dominance (that is, right or left footedness) since this might be expected to determine which foot is used most for starting or stopping movement. A dominant foot might be subjected to greater shearing or mechanical stresses or might be more susceptible to injury by accident.

Twenty five patients with unilateral foot ulceration attending a specialist foot clinic at a district general hospital over four weeks were questioned as to whether they were right or left handed/footed, and we recorded the site of their current foot ulceration. Twenty four of the patients were right footed, of whom 18 had ulceration on the right foot. Compared with the expected number of 12 (assuming equal left/right predominance of ulcers), this was significant (²=6, P<0.02). The single left footed patient had an ulcer on his left foot.

Our data therefore support Coxon and Gallen's finding that foot ulceration in people with diabetes is more common on the right. Given the relatively small numbers of patients who are truly left footed, a much larger study is required to confirm these observations. We conclude that all diabetic feet at risk should be reviewed regularly, with particular attention being paid to the dominant foot.

P M S Evans, Specialist registrar. 
Department of Medicine, University Hospital of Wales, Cardiff CF4 4XN

C Williams, Senior house officer. 
M D Page, Consultant physician. 
East Glamorgan Hospital, Church Village, Pontypridd, Mid Glamorgan CF38 1AB

J C Alcolado, Senior lecturer. 
Department of Medicine, University of Wales College of Medicine, Cardiff CF4 4XN Alcolado{at}cardiff.ac.uk

Study of 15 636 patients found no influence of laterality on risk of amputation

EDITORIn a retrospective audit of a hospital database Coxon and Gallen found that lower limb amputations among patients attending a diabetic hospital clinic occurred with a startlingly high prevalence on the right side compared with the left (ratio 4:1).¹ They speculated that most people favour their right foot during movement and that this leads to increased physical stresses, and consequently increased amputation, on the right side. We disagree with these findings.

We recently completed a screening programme for a large diabetic population in the north west of England, which included recording information about the site of amputations; it has produced results that conflict with those of Coxon and Gallen. In our study, all primary and secondary healthcare providers in six healthcare districts in the north west were invited to allow a research podiatrist to screen their diabetic patients.

Between 1994 and 1998, diabetic patients aged over 18 were screened when attending their annual review or a specific appointment. In total, 15 636 people with diabetes were screened, of whom 190 (1.2%) had a lower limb amputation. Fourteen patients had bilateral amputations, and for 19 the side of the amputation was not specified. Among the remaining 157 patients with unilateral amputations 79 amputations were on the right side and 78 on the left. This shows no difference in laterality of amputation, which was the case at all levels of amputation, whether above knee, below knee, partial foot, or toe amputation.

Our data draw on a large patient base (we included both primary and secondary care) and represent roughly three fifths of the total estimated diabetic population of the participating districts. Our sample differs from that reported by Coxon and Gallen. Their study was based on data collected in a clinical database of hospital diabetic patients, with a prevalence of amputation (11.7%) considerably greater than that in our study or other hospital² and population³ based studies. It is difficult to reconcile the magnitude of disagreement between the results.

We agree with the authors that patient education is important to prevent amputations. It would be misguided, however, on the basis of these data, to encourage patients and healthcare professionals to favour the dominant limb in diabetic footcare programmes.

Caroline A Abbott, Honorary lecturer. 
caroline{at}footclinic.demon.co.uk

Ernest R E van Ross, Consultant in rehabilitation medicine. 
Jai Kulkarni, Consultant in rehabilitation medicine. 
Disablement Services Centre, Withington Hospital, Manchester M20 8LB

Jonathan E Shaw, Research fellow. 
International Diabetes Institute, Caulfield 3162, Victoria, Australia

Anne L Carrington, Research scientist. 
Institute for Diabetes Discovery, Branford, CT 06405, USA

Andrew J M Boulton, Professor of medicine. 
University Department of Medicine, Manchester Royal Infirmary, Manchester M13 9WL

Summary of electronic responses

We received four electronic responses to Coxon and Gallen's article¹ presenting original data on the laterality of lower limb amputation in patients with diabetes (table) published in the eBMJ.^2-5

The weighted average of right sided amputation is 60% (95% confidence interval 57% to 64%). When Coxon and Gallen's study, being an extreme outlier, is excluded no difference between right and left sided lower limb amputation could be found (weighted average 51% (47% to 56%)).