Do treatment quality indicators predict cardiovascular outcomes in patients with diabetes?

PLoS One. 2013 Oct 30;8(10):e78821. doi: 10.1371/journal.pone.0078821. eCollection 2013.

Abstract

Background: Landmark clinical trials have led to optimal treatment recommendations for patients with diabetes. Whether optimal treatment is actually delivered in practice is even more important than the efficacy of the drugs tested in trials. To this end, treatment quality indicators have been developed and tested against intermediate outcomes. No studies have tested whether these treatment quality indicators also predict hard patient outcomes.

Methods: A cohort study was conducted using data collected from >10.000 diabetes patients in the Groningen Initiative to Analyze Type 2 Treatment (GIANTT) database and Dutch Hospital Data register. Included quality indicators measured glucose-, lipid-, blood pressure- and albuminuria-lowering treatment status and treatment intensification. Hard patient outcome was the composite of cardiovascular events and all-cause death. Associations were tested using Cox regression adjusting for confounding, reporting hazard ratios (HR) with 95% confidence intervals.

Results: Lipid and albuminuria treatment status, but not blood pressure lowering treatment status, were associated with the composite outcome (HR = 0.77, 0.67-0.88; HR = 0.75, 0.59-0.94). Glucose lowering treatment status was associated with the composite outcome only in patients with an elevated HbA1c level (HR = 0.72, 0.56-0.93). Treatment intensification with glucose-lowering but not with lipid-, blood pressure- and albuminuria-lowering drugs was associated with the outcome (HR = 0.73, 0.60-0.89).

Conclusion: Treatment quality indicators measuring lipid- and albuminuria-lowering treatment status are valid quality measures, since they predict a lower risk of cardiovascular events and mortality in patients with diabetes. The quality indicators for glucose-lowering treatment should only be used for restricted populations with elevated HbA1c levels. Intriguingly, the tested indicators for blood pressure-lowering treatment did not predict patient outcomes. These results question whether all treatment indicators are valid measures to judge quality of health care and its economics.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Albuminuria / metabolism
  • Blood Glucose / metabolism
  • Blood Pressure
  • Cardiovascular Diseases / complications*
  • Cohort Studies
  • Diabetes Mellitus, Type 2 / blood
  • Diabetes Mellitus, Type 2 / complications*
  • Diabetes Mellitus, Type 2 / therapy*
  • Diabetes Mellitus, Type 2 / urine
  • Female
  • Follow-Up Studies
  • Humans
  • Lipids / blood
  • Male
  • Primary Health Care / statistics & numerical data
  • Proportional Hazards Models
  • Quality Indicators, Health Care*
  • Treatment Outcome

Substances

  • Blood Glucose
  • Lipids

Grant support

The study was funded by the Research Institute SHARE of the Graduate School of Medical Sciences, University of Groningen, University Medical Center Groningen, the Netherlands. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.