Foot surveillance was associated with reduce risk of lower extremity amputation among patients with diabetes

Objective: To evaluate the provision of foot surveillance among patients with diabetes and its association with risk of major amputations. Methods: This was a retrospective study of 399,603 veterans with diabetes and without prior major amputations during fiscal year (FY)1997-1998 using Veteran Health Administrative and Medicare claims data. The follow-up period was FY 1999-2000. We defined foot surveillance to include primary/preventive foot care services in the podiatric and vascular surgery clinics during the baseline 12 months (FY1998). We coded presence/absence of foot surveillance for each quarter in the baseline year and summed these quarterly visit variables into a variable of consistence of care (range: 0-4). We categorized individuals into four risk classification groups according to the consensus of the International Working Group on the Diabetic Foot (Group 0: not defined foot risk condition; Group 1:only microvascular complication including neuropathy, retinopathy or chronic kidney disease; Group 2: microvascular complication and presence of either foot deformity or peripheral vascular diseases; Group 3: foot ulceration or minor lower-extremity amputations. We used Cox proportional regressions to assess the association between foot surveillance and major amputations adjusting for age, sex, race and medical comorbidities for each risk group. Results: There were 3780 incurred major amputations during FY1999-2000; individuals in the more severe foot-risk group had higher major amputation rates (range: 4.3 to 30.3 per 1000). On average, 23.8% had annual foot surveillance. The percentages of having foot surveillance increased with increasing risk classification group severity: 12.9% (Group 0), 24.7% (Group 1), 44.5% (Group 2), and 60.8 % (Group 3). Our multivariate Cox regression models showed that having foot surveillance reduced the risk of major amputation, but only for patients in Groups 2 and 3. For example, patients in Group 3 who received foot surveillance consistently for 3 calendar quarters were 32% less likely to have major amputations than patients who did not have foot surveillance: (adjusted hazard ratio(AHR)= 0.68; 95% CI: 0.58-0.79); in the same Group 3, those who received 4 quarters of surveillance were 42% less likely to have major amputations (AHR=0.58, 95% CI=0.50-0.68). Conclusion: The consistency of foot surveillance was independently associated in a graded fashion with lower risk of major amputations among individuals with diabetes at high risk for foot complications. A low proportion of veteran patients with diabetes had annual foot surveillance. Policy Implications: Foot surveillance may need to be improved and prioritized, and this may results in fewer major amputations.