A Case-Management System for Coronary Risk Factor Modification after Acute Myocardial Infarction

Table. SI Units Systematic modification of coronary risk factors is not integrated into the medical care provided to most of the more than 1 million patients treated annually in the United States for acute myocardial infarction by percutaneous transluminal coronary angioplasty or coronary artery surgery. Most of such patients have lipoprotein abnormalities [1], and nearly one half smoke [2]. These risk factors, which contribute to subsequent morbidity and mortality, remain highly prevalent after acute cardiac events. Failure to integrate comprehensive risk factor modification into the standard medical care provided to patients after acute cardiac events primarily reflects the lack of an organizational framework or system. This deficiency in resource allocation for preventive and rehabilitative aspects of care in turn reflects the predominant orientation of the U.S. health care system to the management of acute illness [3]. Several clinical research studies have shown the effectiveness of risk factor modification, especially treatment of lipoprotein abnormalities [4-7], in achieving regression of coronary artery lesions and reducing the clinical consequences of coronary artery disease [6, 7]. However, risk factor interventions shown to be effective in clinical trials may not prove equally effective in clinical practice because of a paucity of resources, especially nonphysician personnel. The lack of effective management systems limits the expected reduction in morbidity and mortality and the corresponding reduction in medical care costs that motivates current efforts to orient the priorities of the American health care system toward preventive and rehabilitative care. This randomized, controlled trial compared the effectiveness of a physician-directed, nurse-managed, home-based case-management system for coronary risk factor modification with that of usual medical care. Outcomes were measured in both groups immediately after the end of the first year after acute myocardial infarction. The term case-management system has been used in various contexts. As used here, it refers to a system in which a nurse case-manager, working with different health care specialists (a psychiatrist, a cardiologist, a lipid specialist, a nutritionist, and a nurse coordinator), managed coronary risk factors. Methods Enrollment and Orientation Program nurses enlisted patients on hospital day 3 or as soon as their medical condition stabilized. Study participants gave written informed consent to be randomly assigned to a treatment group. Immediately after randomization, program nurses introduced patients to the special intervention with the aid of a videotape. Usual Care The 585 patients in our study were cared for by 215 internists and 34 cardiologists in the five participating medical centers who were organized into practice groups of 5 to 10 physicians each. Cardiology consultation was often provided during hospitalization, but primary responsibility for follow-up care was generally assumed by internists. The usual care offered by the Kaiser Permanente Medical Care Program included physician counseling on smoking cessation and nutritionist counseling on dietary change during hospitalization and physician-managed, lipid-lowering drug therapy after hospital discharge. Group outpatient smoking cessation programs were available for a $50 fee. Group exercise rehabilitation, not generally provided by the Kaiser Permanente Medical Care Program during this study, was available to patients at various community facilities at an average cost of $1800 to $2700 for 3 months' participation. Special Intervention The behavioral interventions in our case-management system, which were offered to the 293 patients in the intervention group in addition to usual care, were derived from social learning theory [8, 9] and modified for medical problems [10]. In this model, persons must learn how to monitor the health habits they seek to change, set attainable subgoals to motivate and direct their efforts, use feedback of progress in ways that promote health, and enlist incentives and social support to sustain the effort needed to succeed [8, 9]. In the hospital, patients were instructed on how to complete self-reports [status reports] of smoking, dietary intake, and exercise. Scheduled interactions between case managers and patients after discharge took three forms: 1) nurse-initiated telephone contacts; 2) computer-generated progress reports mailed to patients based on questionnaires completed by patients and mailed to the nurses; and 3) visits to the program nurse for treadmill exercise testing, initiation of lipid-lowering drug therapy, if indicated, and a single counseling session after a smoking relapse. The maximum number of treatment contacts during the year, including outcome measurement at 6 and 12 months, was as follows: 14 nurse-initiated telephone contacts, 8 patient visits to the blood chemistry laboratory, and 4 patient visits to the nurse case manager. Smoking Intervention Smoking was defined as the use of cigarettes, cigars, cigarillos, pipe tobacco, or any other form of tobacco in the 6 months before admission. Forty-three percent of patients were smokers. Patients who had smoked during the 6 months before hospitalization received the same intensive smoking cessation intervention during hospitalization; this intervention has been described previously [11]. Physicians used a written script that enabled them to provide standardized counseling in less than 2 minutes. The hospital-based smoking cessation counseling focused on relapse prevention. Nurses conducted a standardized smoking history to evaluate patients' addiction to smoking. Patients' reported self-efficacy or confidence to resist smoking in each of 28 potentially high-risk situations was measured; patients were then counseled on how to manage the situations in which they reported less than 70% confidence. Patients also received a relapse prevention manual and a relaxation audiotape. They were advised that the nurse would telephone them 48 hours and 1 week after hospital discharge and at monthly intervals for as long as 6 months. Patients who relapsed were offered one additional visit with the nurse for further counseling. Nicotine polacrilex or transdermal nicotine patches were reserved for highly addicted patients who relapsed after hospital discharge. Nutritional Counseling A computer-based expert system developed by the investigators was used to provide nutritional counseling on a National Cholesterol Education Program [12] Step 2 diet that was low in cholesterol and saturated fat. A food frequency questionnaire designed by the investigators was scored using the Cholesterol and Saturated Fat Index developed by Connor and colleagues [13]. Calculations of cholesterol and saturated fat totals were based on weekly rather than daily average food intakes. Data from the food frequency questionnaires, mailed by patients to the Stanford coordinating center and entered into a microcomputer, were used to generate progress reports that characterized patients' dietary patterns, prioritized dietary change goals, and provided guides for managing difficult situations by directing patients to relevant sections of a nutrition workbook entitled Good Eating for Good Health developed by the program nutritionist. Patients in the intervention group completed a food frequency questionnaire during hospitalization that described their eating habits in the previous month. Patients also completed food frequency questionnaires 6, 11, and 26 weeks after admission. Progress reports were mailed to patients within 48 to 72 hours after the food frequency questionnaires were received. Detailed strategies for maintenance of dietary change were incorporated into the 26-week progress report. Questionnaires to evaluate outcomes were also completed at 36 and 52 weeks. Lipid-Lowering Drug Therapy The therapeutic goal of a plasma low-density lipoprotein (LDL)-cholesterol value of 2.46 mmol/L (95 mg/dL) adopted for this trial was based on the mean post-treatment level of LDL cholesterol found in patients in the study by Blankenhorn and colleagues [4]. Patients with mean plasma LDL cholesterol values (based on measurements in two separate blood samples drawn 75 and 90 days after infarction) that exceeded this value were given initial drug therapy according to the four algorithms shown in Table 1. Patients unable to tolerate bile acid-binding resin or nicotinic acid because of comorbid conditions or potentially adverse interactions with these agents received lovastatin or gemfibrozil. During a visit 90 days after discharge, the nurses did a brief physical examination and obtained a history relevant to hyperlipidemia. They provided detailed counseling to patients regarding the rationale for lipid-lowering drug therapy and ways to maximize drug efficacy and minimize drug side effects, and they advised patients on the schedule of laboratory visits and nurse-initiated follow-up telephone contacts. Table 1. Initial Drug Therapy* Changes in drug therapy at 120, 150, and 180 days, which were coordinated by nurse-initiated telephone contacts, were based on three types of responses to initial therapy: 1) if lipoprotein levels returned to normal, the effective drug therapy was continued; 2) if the response was incomplete, the dose of the effective medication was increased or another drug was added, or both; and 3) if comorbid conditions worsened or blood chemistry abnormalities or intolerable side effects occurred, drug dosage was reduced or the patient was switched to another agent or both. A physician lipid specialist and a Stanford-based senior nurse-coordinator provided telephone consultation to the case managers. Before initiating lipid-lowering drug therapy at 90 days and at each subsequent step, nurses reviewed the patients' blood chemistry and lipoprotein values and elicited any symptoms requiring a change in therapy. The nurs