Chronic neuropathic ulcer is not the most common antecedent of lower limb infection or amputation among diabetics admitted to a regional hospital in Jamaica: results from a prospective cohort study

BACKGROUND Guidelines of the International Consensus on the Diabetic Foot state that "Amputation of the lower extremity or part of it is usually preceded by a foot ulcer". The authors' impression has been that this statement might not be applicable among patients treated in our institution. A prospective cohort study was designed to determine the frequency distribution of antecedents of lower limb infection or gangrene and amputation among adult diabetics admitted to a Regional Hospital in western Jamaica. METHODS Adult diabetics admitted to Hospital with a primary diagnosis of lower limb infection and/or gangrene were eligible for recruitment for a target sample size of 126. Thirty five variables were assessed for each patient-episode of infection and/or gangrene, main outcome variable being amputation during admission or 6-months follow-up. Primary statistical output is the frequency distribution of antecedents/precipitants of lower limb infection and/or gangrene. The data is interrogated by univariate and multivariable logistic regression for variables statistically associated with the main antecedent/precipitant events. RESULTS Data for 128 patient-episodes were recorded. Most common antecedents/precipitants, in order of decreasing frequency, were idiopathic acute soft tissue infection/ulceration (30.5%, CI; 22.6-39.2%), chronic neuropathic ulcer (23.4%, CI; 16.4-31.7%), closed puncture wounds (19.5%, CI; 13.1-27.5%) and critical limb ischemia (7.8%, CI; 3.8-13.9%). Variables positively associated with non-traumatic antecedents/precipitants at the 5% level of significance were male gender and non-ulcerative foot deformity for idiopathic acute soft tissue infection/ulcer; diabetes >5 years, previous infection either limb, insulin dependence and peripheral sensory neuropathy for chronic neuropathic ulcer and older age, diabetes >5 years, hypertension, non-palpable distal pulses and ankle-brachial index ≤0.4 for critical limb ischemia. CONCLUSIONS Chronic neuropathic ulcer accounted for only 23.4 % of lower limb infections and 27.7% of amputations in this population of diabetics, making it the second most common antecedent of either after acute idiopathic soft tissue infection/ulcer at 30.5 and 34.7% respectively. Trauma as a group (defined as closed puncture wounds, lacerations, contusion/blunt trauma and burns) also accounted for a greater number of lower limb infections but fewer amputations than chronic neuropathic ulcer, at 32 and 19.5% respectively.