Comparing the Cardiovascular Risk Reduction in Efficacy and Effectiveness Studies of Lifestyle Modification Interventions for Diabetes Prevention: A Systematic Review and Meta-Analysis Open Access

Young, Stephanie K. (Spring 2019)

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Background: Lifestyle modification are known to prevent or delay type 2 diabetes when delivered under highly controlled conditions (efficacy) and when delivered under real-world conditions (effectiveness). Although efficacy studies are expected to yield larger effects than effectiveness studies, this has not been empirically compared. In this systematic review and meta-analysis, we explored the effects of lifestyle modification (LSM) interventions on cardiovascular risk factors and explored whether effects differ between these two types of studies.

Methods: Two previous systematic reviews and meta-analysis were conducted to identify efficacy and effectiveness studies that tested the effects of LSM on diabetes risk. Studies were systematically identified through MEDLINE, Embase, Cochrane Library and Web of Science databases for efficacy studies and PubMed, Embase, Cochrane Library, and for effectiveness. From these, we selected randomized control trials exploring the impact of LSM interventions. We used random effects meta-analysis to estimate pre- and post-intervention changes on systolic blood pressure (SBP), diastolic blood pressure (DBP), total cholesterol, HDL, LDL, and triglycerides for efficacy and effectiveness studies. We also used arm-based meta-analyses to compare effects between efficacy and effectiveness intervention arms. 

Results: Thirty-one studies (N=7,774, mean age 51.03, 47.89% male) were included in the present meta-analysis. Efficacy LSM interventions were associated reductions in DBP (MD -2.20; 95% CI, -4.07, -0.34) and triglycerides (MD -19.51; 95% CI, -34.54, -4.48) compared to controls. Effectiveness interventions were not associated with significant changes for any outcomes compared to controls.  When comparing the effects of efficacy and effectiveness interventions, efficacy interventions were associated with greater reductions in SBP (MD -4.67; 95% CI, -7.22, -2.14), DBP (MD -2.67; 95% CI, -3.76, -1.58), and triglycerides (MD -20.17; 95% CI, -29.31, -11.04).

Conclusions: Although both efficacy and effectiveness studies show improvement in cardiovascular outcomes in populations at risk for type 2 diabetes, efficacy studies are significantly more beneficial for certain outcomes, namely DBP and triglycerides. Future studies should aim to identify methods and tools that can be used to mitigate the discrepancy between efficacy and effectiveness interventions. In doing so, real-world interventions can achieve similar results to those achieved in clinical trials and other efficacy-based studies.

Table of Contents


The Global Burden of Type 2 Diabetes 1

Diabetes Prevention Interventions 2

Efficacy and Effectiveness of Diabetes Prevention Interventions 4


Efficacy Systematic Review and Meta-Analysis 8

Effectiveness Systematic Review and Meta-Analysis 10

Table 1: Comparison of Methods in Efficacy and Effectiveness Systematic Reviews and Meta-Analyses 13

The Present Meta-Analysis 14

Study Selection 14

Data Extraction 14

Statistical Analysis 15


Study Characteristics 16

Figure 1: PRISMA Study Identification Flow Diagram 17

Table 2: Characteristics of Participants and Studies Included in Meta-Analysis 19

Effect of Lifestyle Modification Interventions on Cardiovascular Measures 20

Table 3: Comparison of Intervention to Control Arms in Efficacy and Effectiveness Studies 20

Comparison of Efficacy Intervention Arms to Effectiveness Intervention Arms 21

Table 4: Comparison of Efficacy Interventions Arms to Effectiveness Intervention Arms 22

Study Quality and Publication Bias 23


Limitations 28




Figure S1. Funnel Plots Representing Heterogeneity Among Study Outcomes 33

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