Effectiveness of Quality Improvement Strategies on the Management of Diabetes: A Systematic Review and Meta-Analysis

Study Questions:

What are the effects of quality improvement (QI) strategies on glycated hemoglobin (HbA1c), vascular risk management, microvascular complication monitoring, and smoking cessation in patients with diabetes?


The authors identified studies through Medline, the Cochrane Effective Practice and Organization of Care database (from inception to July 2010), and references of included randomized clinical trials. Criteria for including were trials assessing 11 predefined QI strategies or financial incentives targeting health systems, health care professionals, or patients to improve management of adult outpatients with diabetes. Two reviewers independently abstracted data and appraised risk of bias. The results included 48 cluster randomized controlled trials, including 2,538 clusters and 84,865 patients, and 94 patient randomized controlled trials, including 38,664 patients.


The mean duration of the intervention trial was 12 months (interquartile range [IQ], 6-12 months) and longest duration of follow-up was 12 months (IQ 6-12 months). In a random-effects meta-analysis, the QI strategies reduced HbA1c by a mean difference of 0.37% (95% CI, 0.28-0.45; 120 trials), low-density lipoprotein (LDL) cholesterol by 0.10 mmol/L (3.87 mg/dl) (0.05-0.14; 47 trials), systolic blood pressure (sBP) by 3.13 mm Hg (2.19-4.06, 65 trials), and diastolic BP (dBP) by 1.55 mm Hg (0.95-2.15, 61 trials) versus usual care. Larger effects were noted when baseline concentrations were >8.0% for HbA1c, >2.59 mmol/L (>100 mg/dl) for LDL cholesterol, and >80 mm Hg for dBP and >140 mm Hg for sBP. The effectiveness of QI strategies varied depending on baseline HbA1c control. QI strategies increased the likelihood that patients received aspirin (11 trials; relative risk [RR], 1.33; 95% CI, 1.21-1.45), antihypertensive drugs (10 trials; RR, 1.17; 1.01-1.37), and screening for retinopathy (23 trials; RR, 1.22; 1.13-1.32), renal function (14 trials; RR, 1.28; 1.13-1.44), and foot abnormalities (22 trials; RR, 1.27; 1.16-1.39). However, statin use (10 trials; RR, 1.12; 0.99-1.28), hypertension control (18 trials; RR, 1.01; 0.96-1.07), and smoking cessation (13 trials; RR, 1.13; 0.99-1.29) were not significantly increased.


Many trials of QI strategies showed improvements in diabetes care. Interventions targeting the system of chronic disease management along with patient-mediated QI strategies should be an important component of interventions aimed at improving diabetes management. Interventions solely targeting health care professionals seem to be beneficial only if baseline HbA1c control is poor.


While the average results of the QIs seem modest, collectively they should result in a robust reduction in cardiovascular event and microvascular complications in diabetes. Research is needed to identify which interventions and combination of QI strategies will optimally improve important outcomes at an acceptable cost to aid the health-system and third-party payers in diabetes and other costly diseases including coronary disease/acute coronary syndrome, depression, asthma, and chronic back and other pain syndromes. Clearly the most cost-effective QI strategy will depend on many demographic and clinical variables, and will evolve with the overall improvement of health education.

Clinical Topics: Acute Coronary Syndromes, Dyslipidemia, Prevention, Lipid Metabolism, Nonstatins, Novel Agents, Statins, Hypertension

Keywords: Depression, Hemoglobin A, Acute Coronary Syndrome, Cost-Benefit Analysis, Follow-Up Studies, Chronic Disease, Insurance, Bias (Epidemiology), Hydroxymethylglutaryl-CoA Reductase Inhibitors, Lipoproteins, Transcription Factors, Disease Management, Coronary Disease, Quality Improvement, Cholesterol, Outpatients, Health Education, Hypertension, Smoking Cessation, Diabetes Mellitus

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