Health care systems have played a central role in the public health response to the growing problem of diabetes (1–2) and its complications. During the 1990s, managed care organizations (MCOs) began seeking system-level approaches to improve diabetes outcomes and control costs in covered populations. Although previous clinical trials (3–6) had demonstrated that several clinical interventions could reduce complication rates and possibly control costs, these findings were not being systematically applied (7,8).
Performance-reporting initiatives, such as the National Committee on Quality Assurance's Diabetes Quality Improvement Program (9), led MCOs to develop disease management programs that used diabetes registries, internal performance monitoring and feedback, physician and patient reminder systems, case management, and provider incentives to improve quality (10,11). Simultaneously, MCOs introduced cost-containment strategies, including utilization review, preauthorization requirements, cost-related incentives, and patient cost-sharing (12).
MCO structures ranged from decades-old not-for-profit group/staff model HMOs to contractual arrangements between traditional indemnity insurers and newly formed provider groups or individual providers. Provider groups ranged from relatively integrated multispecialty group practices to loosely affiliated physician networks or independent practice associations (IPAs). This heterogeneity persists today; however, neither structural variation nor disease management strategies have been carefully studied for their associations with diabetes care quality or patient outcomes.
In 1998, the Centers for Disease Control and Prevention and the National Institute of Diabetes and Digestive and Kidney Diseases launched a multicenter, prospective observational study, the Translating Research into Action for Diabetes (TRIAD) Study (13). The TRIAD Study Group includes investigators from six translational research centers that partnered with ten health plans. These plans contracted with 68 provider groups to deliver primary and specialty care to more than 180,000 diabetic enrollees in 1998. From this population, TRIAD assembled one of the largest cohorts of diabetic patients ever studied, collecting and linking data from patients, providers, provider groups, and health plans.
TRIAD assessed associations between system-level structures and strategies and the quality of diabetes care and patient outcomes using Donabedian's paradigm (14) (Fig. 1). TRIAD also studied patient-level characteristics that may influence outcomes, either directly by affecting patients' abilities to self-manage diabetes or indirectly by affecting interactions with health care systems (Fig. 2). In Fig. 2, we synthesize published TRIAD studies that addressed the influences of either system-level or patient-level characteristics on processes or outcomes for diabetic patients.