Clinical trials have shown that intensified preventive care can improve the prospects of people with diabetes.1,2,3, 5
Disease management programs that incorporate these findings into routine practice are widespread, but published evaluations have been short-term and generally have not measured mortality or other final outcomes.20,21,22,23,24
In this report, we describe the changes that accompanied the implementation over 10 years of a chronic disease management program for diabetes mellitus in a large nonprofit, group-model health maintenance organization.
The steady growth of the diabetes register of the organization parallels national growth trends in the prevalence of diabetes that has persisted since the 1930s.27
The relative contributions of more effective screening, weight gain in the population, and other factors cannot be determined from our data. However, the decline over time in the chronic disease score suggests a major role for better screening, a phenomenon that has also been observed nationally.28
Data show sustained improvement over 10 years in processes of care, such as rates of glycemic monitoring and retinal screening, improvements in biologic risk factors (glycemia, blood pressure, and hyperlipidemia), and a relative reduction in mortality, compared to a matched control population of members without diabetes. These favorable clinical outcomes were accompanied by a reduction, relative to members without diabetes, in the use of services that are resource intensive (such as emergency room and acute hospital care) without a drop in the use of outpatient care. When considered along with other studies that show the efficacy of similar quality-improvement methods in lowering diabetic risk factors,15,16,17,18,19
generally poor processes of care and risk factor levels in the community,29,30,31
and the efficacy of risk-factor reduction in preventing diabetic complications,1,2,3,5
they also suggest that Kaiser Permanente's quality improvement program accounts for much of the observed reduction in risk factors, hospitalization, mortality, and usage of emergency services. This supposition cannot be proved by observational data, however. Because the randomized clinical trial method is not feasible for multimodal, continually evolving institutional programs such as that of Kaiser Permanente North West, such proof may never be forthcoming for programs of this kind.
To help clarify whether observed changes resulted from the implementation of the Kaiser Permanente program, we focused our analysis on performance ratios—measurements for members with diabetes divided by measurements for matched members without diabetes. These ratios show that rates of hospitalization, use of the emergency department, and mortality dropped more rapidly among people with diabetes than among other members of the health plan; they also rule out changes in the age-sex mix of the diabetes registry as explanations for these trends.
The role of the Kaiser Permanente program in producing these results remains confounded, however, by at least three other forces. Decreasing illness levels among entrants to the registry (probably due to earlier recognition of diabetes28
) andgeneral improvement in diabetes care (stimulated by clinical leaders, advocates, and research publications) imply an overestimation of the influence of the Kaiser Permanente program. Contemporaneous improvement in the care of Kaiser Permanente members without diabetes, which undoubtedly occurred and would have reduced the apparent treatment effect, implies an underestimation. The net effect is unknown. At a minimum, however, our results do not rule out the hypothesis that the efforts of the health maintenance organization to improve quality decreased the use of the hospital and emergency department as well as the mortality rate.
Our observational data also do not permit us to infer which aspects of the evolving program were most powerful. Although formal outreach programs had obvious, dramatic effects on rates of retinal screening and immunization, our descriptive approach cannot tease out, for example, the roles of influenza vaccination, glucose control, and lipid management in reducing mortality and hospitalization. Experimentally controlled trials are necessary to address this kind of question.
We do not report on such an experiment, although it is our experience that effective quality improvement efforts make use of all, and any, avenues available in a given setting. In the course of implementation, synergies arise, including considerable momentum around the quality improvement effort, which in itself motivates attentiveness and change. Implementation theorists advocate just this sort of approach that is directed from within the program and takes advantage of multiple models and channels.32,33
Evaluating the frontiers of quality improvement in diabetes care in the real world must include the study of a program that is broadly evolving, mutually interacting, and non-research controlled, but largely evidence-based.
The quality improvement approach undertaken in our study site is not necessarily superior to other possible approaches. Kaiser Permanente itself has been incompletely satisfied, and has embraced other opportunities for improvement, such as a new electronic medical record system and an agreement to link compensation to the achievement of quality-of-care goals. By late 1999, the mean HbA1c in the Kaiser Permanente Northwest registry had dropped to 7.75%, and programs were in place to increase the use of aspirin prophylactically and of antihyperlipidemic agents during 2000.
We did not attempt to measure all the costs and savings associated with this program. Nevertheless, the savings on acute inpatient care that can be extrapolated from our results are equivalent to roughly 4000 days of acute care avoided per 1000 registrants over 10 years. This represents a substantial benefit for people with diabetes and purchasers of health insurance, as well as for the health maintenance organization. A formal estimate of net economic impact would compare these and other savings to direct program costs and to program-stimulated cost increases, such as the costs of increased rates of drug treatment, substitution of more expensive drugs such as statins and angiotensin converting enzyme inhibitors, and more frequent laboratory monitoring. Simulation modeling thus far suggests that the intensification of care will increase the net costs of medical care.34,35,36,37