Implications for practice and research

• Quality-improvement (QI) strategies improved glycated haemoglobin (HbA1c), low-density lipoprotein (LDL-C), cholesterol (TChol) and blood pressure (BP) levels and increased aspirin and antihypertensive drug use in addition to retinopathy, renal and foot screening compared with usual care.

• Further research is needed to identify which diabetes interventions, in combination with QI strategies, improve patient outcomes at an acceptable cost to aid health system planning.

Context

Evidence indicates that patients with diabetes mellitus (DM) may achieve improved physiological outcome with preventative and therapeutic interventions. Given the complexities of DM management, such interventions often require coordinated services of primary care physicians, allied health professionals and subspecialists to effectively assist patients with achievement of improved outcomes. Yet, many patients with DM fail to receive such interventions. Addressing the quality of DM care, a growing body of research has examined the effect of case management, multidisciplinary teams and financial incentives, among others, on DM outcomes. To date, however, the effectiveness of QI strategies on diabetes outcomes remains uncertain. Tricco and colleagues, therefore, conducted a systematic review and meta-analysis to assess the effect of QI strategies on HbA1c, cardiovascular risk management and microvascular complication monitoring.

Findings

A total of 48 cluster RCTs (84 865 patients) and 94 patient RCTs (38 664 patients) were reviewed. Random effects meta-analyses demonstrated QI strategies reduced HbA1c by a mean difference of 0.37% (95% CI 0.28 to 0.45, 120 trials), LDL-C by 3.9 mg/dl (0.05 to 0.14, 47 trials), systolic BP by 3.13 mm Hg (2.19 to 4.06, 65 trials) and diastolic BP by 1.55 mm Hg (0.95 to 2.15, 61 trials) versus usual care. QI strategies increased the likelihood that patients received aspirin (11 trials; RR 1.33, 95% CI 1.21 to 1.45), antihypertensive drugs (10 trials; 1.17, 1.01 to 1.37) and screening for retinopathy (23 trials; 1.22, 1.13 to 1.32), renal function (14 trials; 128, 1.13 to 1.44) and foot abnormalities (22 trials; 1.27, 1.16 to 1.39).

Commentary

Adult outpatient DM care is complex and often requires the coordinated services of primary care physicians, allied health professionals and subspecialists to effectively assist patients in achieving target HbA1c (<7%), BP (<130/80 mm Hg) and LDL (<100 or <70 mg/dl for patients with overt cardiovascular disease) levels. Achievement of target outcomes is warranted to reduce the risk or slow the progression of microvascular (retinopathy, nephropathy and neuropathy) and macrovascular (coronary heart disease, peripheral vascular disease and stroke) complications. Quality diabetes care, in addition to medical management, requires monitoring for complications and promotion of DM self-management, including the acquisition of DM-related knowledge and skills.1

The present systematic review is rigorous and reports the difficulties in consistently classifying complex QI strategies. However, the observed effects provide compelling evidence that QI strategies effectively reduce HbA1c, LDL-C, diastolic and systolic BP levels and increase aspirin and antihypertensive drug use in addition to retinopathy, foot and renal screening compared with usual care. This suggests that widespread implementation of QI strategies is warranted. Data from the UK Prospective Diabetes Study,2 for example, suggested that a 1% reduction in mean HbA1c results in 21% fewer deaths, 14% fewer myocardial infarctions and a 37% decrease in microvascular complications at the population level. Tricco and colleagues recorded a 0.33% reduction in mean HbA1c, which, as the authors suggest, might translate to 7% fewer deaths, 5% fewer myocardial infarctions and 12% fewer microvascular complications at the population level with widespread implementation of QI strategies. Improved physiological outcomes may improve the quality of life for patients with DM and may also demonstrably reduce healthcare costs associated with DM-related complications. Further research is needed to identify which DM interventions, in combination with QI strategies, will optimally improve patient outcomes at an acceptable cost to aid health system planning.