BACKGROUND: Foot examinations are widely recommended as a means to reduce amputation risk, but no investigators have studied their independent effect on this outcome.
METHODS: We conducted a population-based case-control study of primary care provided to Pima Indians from the Gila River Indian Community. Sixty-one Pima Indians with type 2 diabetes and a first lower-extremity amputation between January 1, 1985, and December 31, 1992, were compared with 183 people who had no amputation by December 31, 1992. The type of foot examination conducted, comorbid conditions, and foot risk factors present in the 36 months before the pivotal event were abstracted from medical records. All ulcer care was excluded. The independent effect of foot examinations on the risk of amputation was assessed by logistic regression.
RESULTS: During the 36 study months, 1857 foot examinations were performed on 244 subjects. The median number of preventive foot examinations was 7 for case patients and 3 for control patients. After controlling for differences in comorbid conditions and foot risk conditions, the risk of amputation for persons with 1 or more foot examinations was an odds ratio (OR) of 0.55 (95% confidence interval [CI], 0.2-1.7; P=.31). The risk of amputation associated with written comments of nonadherence with therapeutic foot care recommendations or diabetic medication was an OR of 1.9 (95% CI, 0.9-4.3; P=.10).
CONCLUSIONS: Our study failed to demonstrate that foot examinations decrease the risk of amputation in Pima Indians with type 2 diabetes. However, foot examinations detect high-risk conditions for which specific interventions have been shown to be effective in reducing amputation risk.
Frequent foot examinations are widely recommended as a means of reducing the risk of foot ulcers and amputation in patients with type 2 diabetes.1 This recommendation is primarily based on reports from diabetic foot care programs that provided frequent foot examinations, custom therapeutic footwear, patient education on footwear and foot care, and access to a multidisciplinary team of providers.2-6 None of these reports, however, attempted to identify the specific contribution of foot examinations to the overall success of the program or the optimum frequency of those examinations. There is little evidence to support the recommendation that primary care physicians should perform foot examinations at every visit; yet this recommendation has almost become a universal mandate of diabetes quality-of-care protocols. Furthermore, there is no evidence for what examination components should be included. We conducted a retrospective evaluation of a population-based foot care program to determine the specific contribution of foot examinations to the risk of amputation.
Methods
Pima Indians of the Gila River Indian community in Arizona have one of the world’s highest reported incidence rates of diabetes and diabetic amputation.7,8 Previous studies of this population have identified the demographic, pathophysiologic, and diabetes-related risk factors for lower-extremity amputation.7 Members of this community have participated in a National Institutes of Health (NIH) longitudinal study of diabetes since 1965.8
The Indian Health Service, a branch of the US Public Health Service, provided medical care for this population during the study period. The model diabetes program, started in 1979, included salary support for physicians, diabetes educators, nutritionists, and podiatrists, and culturally appropriate educational materials.9 Because of the large number of people with diabetes in this community, people who had had diabetes for less than 5 years were the central focus of the program. During the early years of the program, a podiatrist was in attendance once a week. In 1988 a full-time podiatrist joined the medical staff, and another joined in 1991. Patients with diabetes for more than 5 years and those with renal, cardiac, or other medical complications received care in the general medicine clinic but could also be seen in the model program clinic. Hospitalization for simple conditions was provided in the community at Hu Hu Kam Memorial Hospital and for more complicated conditions or surgical care at the Phoenix Indian Medical Center, 45 miles away. Clinicians in all health care settings were encouraged to conduct foot examinations on all patients with diabetes. The adherence to these recommendations was monitored with an annual chart audit that began in 1985.10,11
Patients eligible for the study: (1) had diabetes according to World Health Organization criteria,12,13 (2) lived in districts 1 through 5 of the reservation, (3) were 50% or more Pima or closely related Tohono O’odham Indian, (4) were aged between 25 and 85 years, and (5) participated in the longitudinal diabetes study conducted by the National Institutes of Health. The date of onset of each patient’s diabetes was established at these research examinations or between examinations during the course of routine medical care. Case patients had experienced a first nontraumatic amputation of the lower extremity between January 1, 1985, and December 31, 1992, and control patients had no lower-extremity amputation by December 31, 1992.