Reduction of Lower Extremity Clinical Abnormalities in Patients with Non-Insulin-Dependent Diabetes Mellitus

Given that 14 million Americans have diabetes [1], the common complications of this disorder, such as foot ulcers and lower extremity amputations, are of major concern to the medical community. Approximately 20% of all diabetic patients hospitalized in the United States are admitted because of foot complications [2, 3]. Furthermore, about 50% of all nontraumatic amputations in the United States are done in patients with diabetes [1, 4]. This proportion equates to about 55 000 amputations a year [1] or 59.7 amputations for every 10 000 persons with diabetes [5]. Patients who undergo an amputation are at greater risk for a second similar procedure on either the same or the other leg [6, 7]. Yet, it has been estimated that about one half of the amputations in patients with diabetes, or about one fourth of the total amputations done in the United States, are preventable [1, 4]. Recently, the focus has been on preventive strategies that minimize foot damage in diabetic patients and thereby reduce the rates of ulcers and amputations. These preventive strategies are based on two observations: first, that simple efforts on the part of the health care provider or patient can reduce the likelihood of subsequent amputation due to diabetes-associated foot disease [8]; and second, that many of these simple procedures are not being systematically applied by health care providers or patients [9]. For example, studies indicate that physicians infrequently examine the feet of patients with diabetes [9, 10]. Also, most patients with diabetes do not engage in simple foot-care assessments to identify lesions requiring early treatment [11]. Preventive strategies are not systematically applied for several reasons: First, patients may not be aware of foot-care procedures or how to do them, or they may not believe that such procedures can make a difference; second, podiatry and orthopedics services that could assist in foot salvage in diabetic patients may not be available; and, finally, the health care system may make it difficult for patients or health care providers to examine the feet of patients with diabetes [10]. Several uncontrolled studies found that implementation of improved foot-care programs can significantly reduce lower extremity complications in patients with diabetes; these studies showed a 44% to 85% reduction in the rate of lower extremity amputations [4, 12-14]. A recent casecontrol study also supports the implementation of preventive strategies, such as foot care, use of protective footwear, and aggressive treatment of foot infection by patients or health care providers, to decrease the risk for lower extremity amputation [15]. The intervention in our study was designed to reduce the prevalence of risk factors for lower extremity amputations in patients with noninsulin-dependent diabetes and involved the three major elements of a prevention program: the patient, health care providers, and the health care system. Specifically, we did a randomized, controlled trial to determine whether a comprehensive foot-care intervention could improve patients' knowledge and performance of appropriate foot care; increase the number of referrals to specialty clinics such as the podiatry clinic; increase the frequency of foot examinations by health care providers and the documentation of risk factors in the medical record; and improve short-term patient outcomes such as skin and nail conditions known to be risk factors for ulcers and amputations. Methods Setting Our study, the design of which is summarized in Figure 1, was done from April 1989 to March 1991 in the academic general medicine practice of the Regenstrief Health Center in Indianapolis, Indiana [16]. The practice is subdivided into four primary care teams (labeled A, B, C, and D), each with its own nursing and clerical staff. Each team sees patients for eight half-day sessions per week, with each session staffed by one or two faculty internists and two to four housestaff. Teams A and C were randomly assigned to the intervention group; teams B and D were assigned to the control group. Previous studies in which this method of randomization was used have shown no baseline interteam differences in patient characteristics and physician practice behavior and no effect of the team on the study outcome [16-19]. Figure 1. Summary of the study design. Patient Identification and Recruitment The computerized Regenstrief Medical Record System [20] was used to identify approximately 3000 patients with noninsulin-dependent diabetes, as well as the date and time of their next appointment. Only patients with noninsulin-dependent diabetes who were seen at least two times in the preceding year by the same provider were included in the study. Additional criteria for inclusion were as follows: an age greater than 40 years; a diagnosis of diabetes after 30 years of age; a diagnosis of diabetes based on National Diabetes Data Group criteria [21] or the presence of disease requiring medication for the control of hyperglycemia; an intention to obtain care at the general medicine practice for the next 2 years; and a body weight that was either ideal or heavier than ideal. Exclusion criteria included pregnancy; major psychiatric illness, including dementia; terminal illness likely to cause death within 1 year; renal failure (serum creatinine > 440 mol/L); previous bilateral amputations above or below the knee; or an inability to provide any self-care. Patients of investigators involved in the protocol were also excluded from the study. Of the 728 eligible patients, 244 refused to participate, 89 enrolled in the study but failed to keep their appointments for assessment, and 395 were assessed by trained nurse-clinicians. Of the 395 patients assessed, 352 (89%) completed the study; 43 patients (11%) did not complete the study for the following reasons: death (11 patients); change of residence (15 patients); illness (6 patients); transportation problems (3 patients); and miscellaneous reasons (8 patients). Patient Assessment Samples for determining fasting plasma glucose, cholesterol, triglyceride, high-density lipoprotein, hemoglobin A1C, and C-peptide levels were obtained from enrolled patients and immediately transported to a certified laboratory for analysis. Patients gave a history and had a physical examination at study entry and approximately 1 year later (mean, 11.8 1.5 months). These examinations focused on risk factors for amputation and were administered by two trained nurse-clinicians who were blinded to the patients' experimental conditions. Foot-related data derived from the history and physical examination included the patient's self-reported foot-care behaviors; the quality of the patient's examination of his or her feet; the severity of any foot lesions; and the presence of musculoskeletal abnormalities, dermatologic conditions, peripheral vascular disease, and peripheral neuropathy (the neuropathy assessment included quantitative measures of pressure and temperature sensation). Patients were questioned about their regular foot-care routine and were asked to show how they examined their feet. During this self-examination, nurse-clinicians observed whether patients' scrutinized the toenails, the soles of the feet, and the area between toes. Musculoskeletal and dermatologic abnormalities were assessed using standard definitions of findings such as callus, hammer toe, and Charcot foot [3, 22]. The nurse-clinicians palpated the dorsalis pedis, posterior tibial, and femoral pulses bilaterally in their assessment for peripheral vascular disease. If a pulse was absent at any one of the six sites palpated, the assessment was considered abnormal. Foot lesions were rated for severity using the Seattle Wound Classification System [23], which ranges from a grade of 1.1 (absence of lesions) to a grade of 10 (entire foot or leg is gangrenous). In our study, a foot lesion was defined as any wound, with or without functional interruption of the protective cutaneous barrier, ranging from a superficial scratch to an ulcer involving the epidermis. A serious foot lesion was defined by a severity grade of at least 1.3, which indicates a minor, nonulcerated lesion with clinical evidence of healing sufficient to close previous interruption of the cutaneous barrier [23] or a blister. Pressure and temperature sensations were measured using the 5.07-log (0.1 mg)-force Semmes-Weinstein monofilament and the thermal sensitivity testing apparatus, according to standard techniques [24-26]. Thermal sensitivity was considered abnormal if the patient had a value greater than 2 standard deviations from the mean value for a group of healthy persons without diabetes (warm > 2.04 C; cool > 1.58 C). Practice Patterns of Health Care Providers Immediately after each scheduled visit, study patients had a structured interview [10] with a research assistant, who asked about foot self-examination and foot-care education given by health care providers (the primary care physician or nursing personnel). In addition, a chart audit was conducted by a nurse-clinician who was blinded to the patients' experimental condition. Information abstracted from the medical record included the physician's documentation of the findings from the history and physical examination; any referral to podiatry, orthopedics, or vascular surgery clinics; and diagnostic-test ordering related to the evaluation and treatment of diabetes-associated foot problems. Intervention The intervention cohort was exposed to several risk-reduction strategies. The nurse-clinicians conducted the patient education session with one to four patients, covering appropriate foot-care behaviors and footwear, using a commercially available slide and audiotape presentation [27] and pamphlets [28]. Behavioral contracts regarding desired foot-care behaviors were negotiated with each patient. Follow-up was done by telephone 2 weeks after the education sessions to remind patients abo