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Effects of Quality Improvement Strategies for Type 2 Diabetes on Glycemic Control A Meta-Regression Analysis

Kaveh G. Shojania, MD; Sumant R. Ranji, MD; Kathryn M. McDonald, MM; Jeremy M. Grimshaw, MBChB, PhD; Vandana Sundaram, MPH; Robert J. Rushakoff, MD; Douglas K. Owens, MD, MS
JAMA. 2006;296(4):427-440. doi:10.1001/jama.296.4.427.
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Published online

Context There have been numerous reports of interventions designed to improve the care of patients with diabetes, but the effectiveness of such interventions is unclear.

Objective To assess the impact on glycemic control of 11 distinct strategies for quality improvement (QI) in adults with type 2 diabetes.

Data Sources and Study Selection MEDLINE (1966-April 2006) and the Cochrane Collaboration's Effective Practice and Organisation of Care Group database, which covers multiple bibliographic databases. Eligible studies included randomized or quasi-randomized controlled trials and controlled before-after studies that evaluated a QI intervention targeting some aspect of clinician behavior or organizational change and reported changes in glycosylated hemoglobin (HbA1c) values.

Data Extraction Postintervention difference in HbA1c values were estimated using a meta-regression model that included baseline glycemic control and other key intervention and study features as predictors.

Data Synthesis Fifty randomized controlled trials, 3 quasi-randomized trials, and 13 controlled before-after trials met all inclusion criteria. Across these 66 trials, interventions reduced HbA1c values by a mean of 0.42% (95% confidence interval [CI], 0.29%-0.54%) over a median of 13 months of follow-up. Trials with fewer patients than the median for all included trials reported significantly greater effects than did larger trials (0.61% vs 0.27%, P = .004), strongly suggesting publication bias. Trials with mean baseline HbA1c values of 8.0% or greater also reported significantly larger effects (0.54% vs 0.20%, P = .005). Adjusting for these effects, 2 of the 11 categories of QI strategies were associated with reductions in HbA1c values of at least 0.50%: team changes (0.67%; 95% CI, 0.43%-0.91%; n = 26 trials) and case management (0.52%; 95% CI, 0.31%-0.73%; n = 26 trials); these also represented the only 2 strategies conferring significant incremental reductions in HbA1c values. Interventions involving team changes reduced values by 0.33% more (95% CI, 0.12%-0.54%; P = .004) than those without this strategy, and those involving case management reduced values by 0.22% more (95% CI, 0.00%-0.44%; P = .04) than those without case management. Interventions in which nurse or pharmacist case managers could make medication adjustments without awaiting physician authorization reduced values by 0.80% (95% CI, 0.51%-1.10%), vs only 0.32% (95% CI, 0.14%-0.49%) for all other interventions (P = .002).

Conclusions Most QI strategies produced small to modest improvements in glycemic control. Team changes and case management showed more robust improvements, especially for interventions in which case managers could adjust medications without awaiting physician approval. Estimates of the effectiveness of other specific QI strategies may have been limited by difficulty in classifying complex interventions, insufficient numbers of studies, and publication bias.

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Figure 1. Search Strategy and Article Review Process
Graphic Jump Location

“Excluded topic” applied to studies focused predominantly on diabetes in pregnancy, type 1 diabetes, or diabetes in children/adolescents, screening for new diagnoses of diabetes, preventing diabetes in high-risk patients, and inpatient management of diabetes. The predominant reason for exclusion under “Other” was omission of key data (eg, numbers of patients or preintervention glycosylated hemoglobin [HbA1c] values9499), which applied to 8 studies. Full text review was conducted by 2 independent reviewers, with conflicts resolved by consensus among 3 reviewers. EPOC indicates Cochrane Collaboration's Effective Practice and Organisation of Care group.
*More than 1 design could be reported in single article.

Figure 2. Postintervention Differences in Serum HbA1c Values After Adjustment for Study Bias and Baseline HbA1c Values
Graphic Jump Location

Negative estimates favor intervention groups over control groups for the indicated quality improvement (QI) strategy. These estimates were derived from a meta-regression model with adjustment for the effects of study size (at least as many patients as the median among all included studies vs not) and a dichotomous variable that equaled 1 if the mean baseline glycosylated hemoglobin (HbA1c) value was ≥8.0%. Thus, the point estimate of −0.67% for team changes indicates that, given a large study (ie, having at least as many participants as the median of 180 patients) in which the mean baseline HbA1c values were 8.0% or higher, the intervention group would have a follow-up HbA1c value 0.67% lower than the follow-up value in the control group.

Figure 3. Random-Effects Meta-analysis of Trials Involving Case Management
Graphic Jump Location

Across the 26 trials that evaluated interventions that included case management, the pooled reduction in glycosylated hemoglobin (HbA1c) values was 0.59% (95% confidence interval [CI], 0.41% to 0.77%). For the 15 trials in which case managers required physician approval prior to making medication changes, the pooled reduction in HbA1c values was only 0.41% (95% CI, 0.20% to 0.62%), compared with 0.96% (95% CI, 0.52% to 1.41%) for the 11 trials in which nurse or pharmacist case managers could make independent medication changes (P = .003). Adjusting for trial size and baseline HbA1c values altered these results only slightly, with a mean reduction in HbA1c values of 0.86% (95% CI, 0.45% to 1.28%) for case management interventions in which case managers could make independent medication changes, compared with 0.40% (95% CI, 0.02% to 0.78%) for other case management interventions (P = .04). The sizes of data markers indicates the relative weight of each trial in the meta-analysis, which reflects the precision of the estimate from the trial (largely determined by the number of patients in the trial).



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