Matching the numerator with an appropriate denominator to demonstrate low amputation incidence associated with a London hospital multidisciplinary diabetic foot clinic

Diabet. Med. 27, 1304–1307 (2010) Abstract Aims  To establish a method to assess amputation incidence that addresses the problems matching a numerator with an appropriate denominator in London and to demonstrate low amputation incidence associated with the activity of our multidisciplinary diabetic foot clinic. Methods  Hospital-coded inpatient data was examined to derive the numerator: the number of non-traumatic amputations performed on subjects with diabetes each financial year where the Primary Care Trust commissioner code was our main local Primary Care Trust. Denominators were derived from the main local Primary Care Trust’s Quality and Outcomes Framework data sets. Not all Primary Care Trust subjects with diabetes receive inpatient care at our hospital, so that the denominators were corrected for the hospital’s percentage market share for the provision of inpatient diabetes care for the Primary Care Trust each financial year, derived from the Dr Foster database. Results  Between April 2004 and April 2009, 44 Primary Care Trust subjects with diabetes underwent 34 minor and 10 major amputations at the hospital. Although the Primary Care Trust populations with and without diabetes increased, the hospital’s Primary Care Trust percentage market share decreased, so that overall denominators decreased. The mean annual incidence of minor, major and total amputations over the five financial years was 14.7, 4.2 and 18.9 per 10 000 subjects with diabetes, respectively, and 3.9, 1.1 and 5.0 per 100 000 of the general population, respectively. Conclusions  We report for the first time amputation incidence in a London population. Acknowledging the limitations of accurately defining incidence in London, we demonstrate low amputation incidence associated with our multidisciplinary diabetic foot clinic.