Article
The effectiveness of disease and case management for people with diabetes: A systematic review

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Abstract

Overview: This report presents the results of a systematic review of the effectiveness and economic efficiency of disease management and case management for people with diabetes and forms the basis for recommendations by the Task Force on Community Preventive Services on the use of these two interventions. Evidence supports the effectiveness of disease management on glycemic control; on screening for diabetic retinopathy, foot lesions and peripheral neuropathy, and proteinuria; and on the monitoring of lipid concentrations. This evidence is applicable to adults with diabetes in managed care organizations and community clinics in the United States and Europe. Case management is effective in improving both glycemic control and provider monitoring of glycemic control. This evidence is applicable primarily in the U.S. managed care setting for adults with type 2 diabetes. Case management is effective both when delivered in conjunction with disease management and when delivered with one or more additional educational, reminder, or support interventions.

Introduction

Diabetes mellitus (diabetes) is a prevalent, costly condition that causes significant morbidity and mortality. In the United States, 15.7 million people (5.9% of the total population) have diabetes, of whom 5.4 million are undiagnosed.1 In 1997 alone, 789,000 new cases were diagnosed.1 Moreover, according to death certificate data, diabetes is the seventh leading cause of death in the United States.1 Mortality is primarily related to heart disease: adults with diabetes have death rates from heart disease about 2 to 4 times higher than those without diabetes.1 In addition, the risk of stroke is 2 to 4 times higher in people with diabetes. Diabetes is the leading cause of new cases of blindness in adults aged 20 to 74 years, and it is also the leading cause of end-stage renal disease, accounting for about 40% of new cases. Neuropathy is also a major problem, as 60% to 70% of people with diabetes have this condition, and more than half of lower limb amputations occur among people with diabetes. Finally, the rate of pregnancies resulting in death of the newborn is twice as high among women with diabetes than among those without this disorder.1

Consistent with its extraordinary effect on the health of Americans, the costs of diabetes to the U.S. healthcare system are enormous: total (direct and indirect) costs were estimated at $98 billion in 1997.2 Selby et al.3 calculated that per-person expenditures for members of a managed care organization with diabetes were 2.4 times higher than for those without diabetes. Thirty-eight percent of the total excess costs was spent on treating long-term complications, particularly coronary heart disease.

Traditionally, healthcare delivery involves individual providers reacting to patient-initiated complaints and visits. Care is frequently fragmented, disorganized, duplicative, and focused on managing established disease and complications. Providers practice what they have been taught and what their anecdotal experiences have led them to believe is effective. The goals are generally short term, such as pain control or avoidance of hospital admission. Management is provider-directed and focuses on pharmacologic and technologic interventions, with little attention to patient self-management behaviors or provider-patient interactions.4

Traditional methods of healthcare delivery do not adequately address the needs of individual people or populations with diabetes. For example, in a survey of the care received by patients of primary care providers, people with diabetes were receiving only 64% to 74% of the services recommended by the American Diabetes Association (ADA) Provider Recognition Program.5 And in a chart audit covering 1 year in a health maintenance organization (HMO) setting, glycated hemoglobin (GHb)a values were documented for only 44% of people with diabetes (ADA recommends two to four measurements per year), and annual urine protein measurements were performed on only 48% of patients.6

Available evidence shows that improving care for people with diabetes results in cost savings for healthcare organizations. In a review of economic analyses of interventions for diabetes, eye care and preconception care were found to be cost saving, and preventing neuropathy in type 1b diabetes and improving glycemic control with either type 1 or type 2 diabetes were found to be clearly cost-effective.7 Gilmer et al.8 modeled cost savings at an HMO and found that every percentage point increase in hemoglobin A1c (HbA1c) above normal was associated with a significant increase in costs over the next 3 years. Testa et al.9 noted that improved glycemic control was associated with short-term decreases in healthcare utilization, increased productivity, and enhanced quality of life. Wagner et al.10 found that a sustained reduction in HbA1c was associated with cost savings among adults with diabetes within 1 to 2 years of improved glycemic control.

In the last decade, innovative interventions for healthcare delivery have emerged that show promise for improving care, outcomes, and costs for individuals and populations with diabetes. Disease and case management are two such new interventions. This review examines the extent and quality of the evidence of their effectiveness when applied to people with diabetes.

Section snippets

The guide to community preventive services

The systematic reviews in this report represent the work of the independent, nonfederal Task Force on Community Preventive Services (the Task Force). The Task Force is developing the Guide to Community Preventive Services (the Community Guide) with the support of the U.S. Department of Health and Human Services (DHHS) and in collaboration with public and private partners. The Centers for Disease Control and Prevention (CDC) provides staff support to the Task Force to develop the Community Guide

Methods

The Community Guide’s methods for conducting systematic reviews and linking evidence to effectiveness are described elsewhere.22, 23 In brief, for each Community Guide topic, a systematic review development team representing diverse disciplines, backgrounds, and work settings conducts a review by

  • developing an approach to identifying, organizing, grouping, and selecting interventions for review;

  • developing an analytic framework depicting interrelationships between interventions, populations, and

Disease management

Disease management has played a prominent role in innovative systems of clinical care over the past two decades. The earliest application of a disease-focused intervention involved prescription drugs,52 and the first use of the term disease management appears to have been in the late 1980s at the Mayo Clinic.53 In the mid-1990s the term emerged in the general medical literature, and by 1999 approximately 200 companies offered disease management services.54 The initial focus of disease

Research issues for disease and case management interventions in diabetes

Even though disease and case management were found effective in the managed care setting for improving glycemic control and provider monitoring of certain important outcomes, several important research gaps were identified in this review. One of the most pressing needs is to better define effective interventions. Disease management has multiple component interventions. To make optimal use of resources, however, only the interventions that contribute most to positive outcomes should be

Conclusions

According to Community Guide rules of evidence,22 strong evidence exists that disease management interventions are effective in improving glycemic control in people with diabetes and in improving provider monitoring of GHb and screening for diabetic retinopathy. There is sufficient evidence that disease management is effective in improving provider screening for foot lesions and peripheral neuropathy, screening of urine for protein, and monitoring of lipid concentrations. For case management,

Acknowledgements

The authors thank Stephanie Zaza, MD, MPH, for support, technical assistance, and editorial review; Kristi Riccio, BSc, for technical assistance; and Kate W. Harris, BA, for editorial and technical assistance. The authors acknowledge the following consultants for their contribution to this manuscript: Tanya Agurs-Collins, PhD, Howard University Cancer Center, Washington, DC; Ann Albright, PhD, RD, California Department of Health Services, Sacramento; Pam Allweiss, MD, Lexington, KY; Elizabeth

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