In the third session, we discuss the advantages and disadvantages of three methods to present “benefit”: changes in risk calculators, using relative risk, or the absolute benefit. We review the challenges of absolute vs relative risk (or relative vs absolute truth) and discuss patient expectations in regards to the medical miracle of prevention. The duration of therapy is put in context of the epoch time frames of risk calculators and studies.

Show Notes

Definitions

CVD is cardiovascular disease and typically refers to the combination of CHD (coronary heart disease – fatal and non-fatal MIs and sometimes angina) PLUS cerebrovascular disease (fatal and non-fatal strokes – and sometimes TIAs) PLUS (sometimes) other conditions (heart failure, peripheral vascular disease)

Calculating benefit

1. Change the factor and recalculate the chance of CVD
2. Use the relative benefits seen in clinical trials (typically 5 years in duration) and apply them to the chance calculated for your patient
3. Avoid the use of CDV calculators and just use the absolute benefits seen in clinical trials

A synopsis of the relative benefit of drugs

• Statins ? 30%? in CHD (0%? in women)? 5 years
• BP ? 40 %? in strokes and ? 20%? in CHD ? 5 years
• Metformin ? 35%? in CHD and stroke ? 8-10 years

A synopsis of the absolute benefit of drugs

Statins over 5 years in a post MI patient Coronary events ?4% (15% to 11%) Death ?2% (12% to 10%) Strokes ?1% (5% to 4%) Treating a Blood Pressure of 160 /100 mmHg for 5 years CVD ? 1% (4% to 3%)

Absolute benefit of statins over approx 5 years

* just in males and NO difference in overall serious adverse events

In episode 58, the fourth in our installment of podcasts on diabetes, we briefly talk about the evidence surrounding intensive glucose lowering (ACCORD, ADVANCE, VADT and UKPDS trials) – podcasts #9 and #38 did this in more detail. At the end of the podcast, Mike identifies many of James’ flaws, but does it with compassion and kindness; at least he says he does.

Show Notes

1) Does tight glycemic control burden patients with complex treatment programs, hypoglycemia, weight gain, and costs and offers uncertain benefits in return?

Ann Int Med 2009;150:803-8

2) ACCORD and ADVANCE studies

Click here for a synopsis of the results

N Engl J Med 2008 358:2545-2559

N Engl J Med 2008 358:2560-2572

Also listen to Episode 9: News Flash: Aggressive Blood Sugar Control Not All Sweet

3) VADT trial N Engl J Med 2009;360:129-39

Also listen to Episode 38: New trials you need to know about

4) Glucose lowering meta-analysis – do the results support the conclusions?

Lancet 2009; 373:1765-72

5) UKPDS data

BMJ 2000;320:1720-3

6)UKPDS – 10 year update (recent results)

NEJM 2008;359:1577-89

Episode 52 goes back in time to look in more detail at what we talked about in episode 30; the whole issue of CRP measurement. Mike and James start at the “large” issue of intra-subject variability, then focus on the “small” impact CRP has on absolute risk assessment, and briefly discuss how “accurate” risk assessments are in the first place. Finally they come to the conclusion that, as with most of the podcasts, they are very accurately vague and there is huge intra-podcaster variability.

Show Notes

1) Issues of intra-subject CRP measurement variability

Clinical Chemistry 2001;47:444–50

2) Need for repeat and multiple values

Clinical Chemistry 1997;43:52–8

Ann Clin Biochem 2002;39:85-8

3) Impact on risk assessment of adding CRP to other risk factors

“Our findings suggest that routine measurement of these novel markers [CRP] is not warranted for risk assessment”

Arch Intern Med 2006;166:1368-73

“the addition of multimarker scores [CRP] to conventional risk factors resulted in only small increases in the ability to classify risk” 

NEJM 2006;355;2631-9

“CRP does not perform better than the Framingham risk equation for discrimination. The improvement in risk stratification or reclassification …is small and inconsistent”

Int J Epidem 2009;38:217–31

4) Reclassification in risk level when using CRP

Women

Ann Int Med 2006;145:21-9

Men

Circulation 2008;118:2243-51

Net reclassification less than that seen in the above studies

Circ Cardiovasc Qual Outcomes 2008;1:92-7

5) Issue of confidence intervals around risk assessments

J Cardiovasc Risk 2002;9:183-90