Medical records from Hu Hu Kam Memorial Hospital, Phoenix Indian Medical Center, and the Gila River home health agency were obtained by a nurse trained in data abstraction. The pivotal or precipitating event leading to an amputation was identified for each case, and the date of the event was recorded after confirmation by a study podiatrist. A “pivotal event” has been defined as one that triggers others, culminating in an amputation.14 Examples include acute minor trauma (stepping on a tack) or repetitive minor trauma (new shoes creating a blister). The pivotal event date was then assigned to 3 randomly selected control patients for every case patient.
Typically, a pivotal event results in a break in the cutaneous barrier, leading to a wound or ulcer, which in turn increases health care use and alters the focus of preventive efforts. Because we were interested in the preventive effect of examinations, we restricted our data collection to the 36 months before the pivotal event. All health care use, including ambulatory visits, hospitalizations, and home health care, was abstracted for the 36-month period before the pivotal event. The number of visits to each type of clinic was recorded along with the number of failed (or no-show) appointments.
Every foot examination was abstracted for clinic type, provider discipline, type of examination, findings, and therapeutic interventions. Three types of preventive foot examination were defined: (1) foot scan-a visual scan of the skin for breaks in the cutaneous barrier only; (2) comprehensive foot examination-foot scan plus evaluation of bony deformities and neurologic and vascular status; and (3) therapeutic examination-an examination during a therapeutic maneuver, such as debridement of callus or thick nails, prescription or dispensing of therapeutic footwear, or surveillance of the site of a healed foot ulcer. All examinations for foot wound management (acute injury, chronic foot ulcers, and a final visit to confirm wound healing) or for monitoring pedal edema were excluded.
Patients occasionally had foot examinations by more than one provider on the same day. For example, a patient with a new foot wound might be examined first by a nurse, then by a physician, and finally by a podiatrist. Because this team management approach might inflate the number of preventive examinations, we considered multiple foot examinations on the same day as a single one and assigned it to the provider with the most foot-specific training according to the following hierarchy: (1) health aide, nurse, dietician, pharmacist, or physician assistant; (2) physician; and (3) podiatrist, orthopedic surgeon, or physical therapist. For the same reason, all foot examinations during a hospitalization were counted as only one.
All instances of nail and callus care, advice and fitting of therapeutic footwear, and education on foot care were abstracted, including interventions provided during ulcer care or hospitalization. Any written comment on nonadherence with foot care recommendations or diabetic medication from any visit was also noted.
Health conditions and diabetes complications (diabetic retinopathy, nephropathy, cardiovascular disease) diagnosed before the pivotal event date were recorded,15 as were the values for the first 3 blood glucose determinations in each of the 3 years preceding that same event.
We compared means of continuous variables with t tests, and categorical variables with chi-square tests. Health care use variables with a large proportion of 0 values were stratified and compared with chi-square tests. A previously developed logistic model controlled for differences in demographics, diabetes severity, and foot risk conditions.15 We added preventive foot care and patient nonadherence to recommendations to this base model. Competing non-nested models incorporating the 3 types of preventive foot examination variables, either separately or combined, were compared using Schwarz’s Bayesian criterion16 to identify the best means of modeling preventive foot examinations.
Results
Sixty-one first nontraumatic amputations of the lower extremity were identified.15 The clinical characteristics of the 61 case patients and 183 control patients are shown in Table 1.
The 61 case patients and 183 control patients received 1857 foot examinations during the 36 months before the pivotal event. Almost one third of the foot examinations were for wound and ulcer care. The number of foot examinations, by type and provider, are shown in Table 2.
After excluding the duplicate examinations conducted on the same day and any examinations for wound care, 1166 preventive examinations were performed during the 36 months of assessment. The distribution of these preventive foot examinations for all patients is shown in Table 3. Case patients were more likely to receive a foot scan or a therapeutic intervention (nonulceration care). Foot scans were performed at least once during the 36 months in 87% of the case patients and 72% of the control patients. Thirty-eight percent of the case patients received one or more therapeutic interventions, compared with only 17% of the control patients. One third of each group received at least one comprehensive examination during the assessment period. The median number of preventive foot examinations was 7 for case patients and 3 for control patients.