Effects of thiazolidinediones on cardiovascular events in patients with type 2 diabetes mellitus after drug-eluting stent implantation: a retrospective cohort study using the national health insurance database in Taiwan

Effects of Clopidogrel and Proton Pump Inhibitors on Cardiovascular Events in Patients with Type 2 Diabetes Mellitus after Bare Metal Stent Implantation: A Nationwide Cohort Study

Background

To investigate whether there is an increased risk of cardiovascular (CV) events in patients with diabetes associated with adding proton pump inhibitors (PPIs) to clopidogrel (CLO) therapy after bare-metal stent (BMS) deployment.

Methods

We used the National Health Insurance Research Database to conduct this retrospective cohort study. We enrolled 6,757 patients with diabetes who underwent BMS deployment and received CLO with/without PPIs for 90 days (6,243 in the CLO subgroup and 514 in the CLO plus PPI subgroup). The endpoints were acute coronary syndrome and re-admission for revascularization (PCI or coronary artery bypass graft surgery) after 3, 6, and 12 months.

Results

The patients who received CLO with PPIs had no significant increase in adverse CV events compared to those without PPIs within 1 year after BMS deployment [3-month hazard ratio (HR) = 0.87, 95% confidence interval (CI), 0.65-1.15; 6 months, HR = 0.95, 95% CI, 0.78-1.15; 1 year, HR = 0.60, 95% CI, 0.81-1.12].

Conclusions

In patients with diabetes undergoing BMS deployment, there was no evidence of an increased risk of CV events among concomitant users of CLO and PPIs. Our results indicate that the use of PPIs may not modify the protective effect of CLO after BMS implantation.

Effect of Pioglitazone in Preventing In-Stent Restenosis after Percutaneous Coronary Intervention in Patients with Type 2 Diabetes: A Meta-Analysis

Background

The benefits of pioglitazone in patients with type 2 diabetes mellitus (T2DM) after percutaneous coronary intervention (PCI) is unclear.

Objectives

To evaluate the effect of pioglitazone on prevention of in-stent restenosis (ISR) in patients with T2DM after PCI.

Methods

All full-text published relevant studies compared the effect of pioglitazone with control group (placebo or no pioglitazone treatment) on ISR in patients with T2DM after PCI were identified by searching the databases including PubMed, EMBASE, Cochrane Library and ISI Web of Science through October 2015. The endpoints were defined as the rate of ISR, late lumen loss, in-stent neointimal volume, target lesion revascularization (TLR) and major adverse cardiac events (MACE).

Results

Six studies (5 RCTs and 1 retrospective study), comprising 503 patients, were included into this meta-analysis. In the pioglitazone group, as compared with the control group, the risk ratio for ISR was 0.48 (I² = 14.5%, P = 0.322; 95%CI 0.35 to 0.68, P<0.001), the risk ratio for TLR was 0.58 (I² = 6.0%, P = 0.363; 95%CI 0.38 to 0.87, P = 0.009). The result showed there was no association between the use of pioglitazone and the events of MACE (I² = 36.7%, P = 0.209; RR 0.56, 95%CI 0.30 to 1.05, P = 0.071). For the considerable heterogeneity, further analysis was not suitable for the endpoints of late lumen loss (I² = 81.9%, P<0.001) and neointimal volume (I² = 75.9%, P = 0.016).

Conclusions

The treatment of pioglitazone was associated with a reduction in ISR and TLR in T2DM patients suffering from PCI, except the incidence of MACE.

Observational studies of the association between glucose-lowering medications and cardiovascular outcomes: addressing methodological limitations

BACKGROUND

Recent years have witnessed a growing body of observational literature on the association between glucose-lowering treatments and cardiovascular disease. However, many of the studies are based on designs or analyses that inadequately address the methodological challenges involved.

METHODS

We reviewed recent observational literature on the association between glucose-lowering medications and cardiovascular outcomes and assessed the design and analysis methods used, with a focus on their ability to address specific methodological challenges. We describe and illustrate these methodological issues and their impact on observed associations, providing examples from the reviewed literature. We suggest approaches that may be employed to manage these methodological challenges.

RESULTS

From the evaluation of 81 publications of observational investigations assessing the association between glucose-lowering treatments and cardiovascular outcomes, we identified the following methodological challenges: 1) handling of temporality in administrative databases; 2) handling of risks that vary with time and treatment duration; 3) definitions of the exposure risk window; 4) handling of exposures that change over time; and 5) handling of confounding by indication. Most of these methodological challenges may be suitably addressed through application of appropriate methods.

CONCLUSIONS/INTERPRETATION

Observational research plays an increasingly important role in the evaluation of the clinical effects of diabetes treatment. Implementation of appropriate research methods holds the promise of reducing the potential for spurious findings and the risk that the spurious findings will mislead the medical community about risks and benefits of diabetes medications.