Heterogeneity and Comparative Effectiveness: Implications for Studies, Reviews, and Policy (Text Version)

Slide presentation from the AHRQ 2010 conference.

On September 28, 2010, David Atkins made this presentation at the 2010 Annual Conference. Select to access the PowerPoint® presentation (424 KB). Free PowerPoint® Viewer (Plugin Software Help).


Slide 1

Atkins1. Heterogeneity and Comparative Effectiveness: Implications for Studies, Reviews, and Policy

Heterogeneity and Comparative Effectiveness: Implications for Studies, Reviews, and Policy

David Atkins, MD, MPH
Health Services Research and Development
Quality Enhancement Research Initiative
Dept. of Veterans Affairs

Images: The Department of Veterans Affairs and Department of Defense logos. These two logos appear on all subsequent slides.

Slide 2

Atkins Slide 2. Session Overview: How to Examine for Heterogeneity and Its Implications

Session Overview: How to Examine for Heterogeneity and Its Implications

  • Within an individual study.
  • Within a systematic review or meta-analysis.
  • In Policy Decisions.
  • Conclusions.

Slide 3

Atkins Slide 3. Heterogeneity of treatment effect

Heterogeneity of treatment effect

  • Non-random variation in direction or magnitude of individual treatment effects within a population.
  • May be due to factors specific to patient, provider, environment, or treatment.
  • Also referred to as clinical heterogeneity.

Slide 4

Atkins Slide 4. "Clinical trials are good experiments but poor surveys." -N. Longford

"Clinical trials are good experiments but poor surveys." —N. Longford

Image: A graph depicts what happens when individuals are sampled from the population:

Sample 1 generates a correct estimate of the average treatment effect but under-represents variation (HTE).

Sample 2 is not only under-represents variation but misrepresents the average.

Only sample 3 gives good population estimates of both the average effect and HTE.

Slide 5

Atkins Slide 5. Heterogeneity vs. Applicability

Heterogeneity vs. Applicability

  • HTE—How great is variation in the treatment effect for individuals within the study population relative to the "average" effect in that population?
  • Applicability—Do the results for the study population apply to a specific patient, group or setting of interest (outside of the study)?

Slide 6

Atkins Slide 6. "Clinical trials are good experiments but poor surveys." -N. Longford

"Clinical trials are good experiments but poor surveys." —N. Longford

Image: A graph depicts what happens when individuals are sampled from the population:

Sample 1 generates a correct estimate of the average treatment effect but under-represents variation (HTE).

Sample 2 is not only under-represents variation but misrepresents the average.

Only sample 3 gives good population estimates of both the average effect and HTE.

Slide 7

Atkins Slide 7. Relevance in Policy Debates

Relevance in Policy Debates

  • Concern that "average" effects don't apply to individual patients.
  • "Cookbook medicine."
  • Decisions based on CER that ignore heterogeneity might deny clinicians ability to individualize treatment decisions.

Slide 8

Atkins Slide 8. Is alendronate (Fosamax) better than calcium and vitamin D to prevent fracture?

Is alendronate (Fosamax) better than calcium and vitamin D to prevent fracture?

  • What factors might cause heterogeneity in the net benefits of alendronate vs. calcium/vitamin D?
  • Audience response

Slide 9

Atkins Slide 9. Sources of Heterogeneity in Net Benefits of Treatment

Sources of Heterogeneity in Net Benefits of Treatment

  • Responsiveness to treatment:
    • e.g., Calcium intake, vitamin D status.
  • Vulnerability to harms:
    • ? Risks from bisphosphonates
  • Baseline risk in absence of treatment:
    • Age, health status, bone density
  • Values attached to outcomes:
    • Convenience of regimens

Slide 10

Atkins Slide 10. Scenario

Scenario

  • 63 year old woman with diabetes and ischemic heart disease, evaluated for cardiac procedure to address increasing exertional chest pain despite optimal medical therapy. She has two-vessel disease with preserved LV function. She is pondering whether to have PCA with stent or bypass.

Slide 11

Atkins Slide 11. Question

Question

  • Is bypass surgery or percutaneous coronary intervention (PCI) superior for treating coronary artery disease?
  • Does the answer depend on patient or intervention factors (i.e. is there heterogeneity of the treatment effects )?
Current as of December 2010
Internet Citation: Heterogeneity and Comparative Effectiveness: Implications for Studies, Reviews, and Policy (Text Version). December 2010. Agency for Healthcare Research and Quality, Rockville, MD. http://www.ahrq.gov/news/events/conference/2010/atkins1/index.html