A meta-analysis of interventions to improve care for chronic illnesses

Objective: To use empirical data from previously published literature to address 2 research questions: (1) Do interventions that incorporate at least 1 element of the Chronic Care Model (CCM) result in improved outcomes for specific chronic illnesses? (2) Are any elements essential for improved outcomes? Study Design: Meta-analysis. Methods: Articles were identified from narrative literature reviews and quantitative meta-analyses, each of which covered multiple bibliographic databases from inception to March 2003. We supplemented this strategy by searching the MEDLINE database (1998-2003) and by consulting experts. We included randomized and nonrandomized controlled trials of interventions that contained 1 or more elements of the CCM for asthma, congestive heart failure (CHF), depression, and diabetes. We extracted data on clinical outcomes, quality of life, and processes of care. We then used random-effects modeling to compute pooled standardized effect sizes and risk ratios. Results: Of 1345 abstracts screened, 112 studies contributed data to the meta-analysis: asthma, 27 studies; CHF, 21 studies; depression, 33 studies; and diabetes, 31 studies. Interventions with at least 1 CCM element had consistently beneficial effects on clinical outcomes and processes of care across all conditions studied. The effects on quality of life were mixed, with only the CHF and depression studies showing benefit. Publication bias was noted for the CHF studies and a subset of the asthma studies. Conclusions: Interventions that contain at least 1 CCM element improve clinical outcomes and processes of care-and to a lesser extent, quality of life-for patients with chronic illnesses.