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Renal denervation, an investigational catheter-based treatment for resistant hypertension, appears to be cost-effective based on the likely long-term clinical benefits, including improved survival, that would result from the substantial reduction in systolic blood pressure achieved by the therapy. The findings were published online September 12, 2012, ahead of print in the Journal of the American College of Cardiology.

Investigators led by Jan B. Pietzsch, PhD, of Wing Tech (Menlo Park, CA), developed a health-economic model to project 10-year and lifetime probabilities of cardiovascular events and cost-effectiveness of renal denervation with the Symplicity system (Medtronic Ardian, Menlo Park, CA) compared with standard of care medical therapy alone.

The model looked at a population similar to that of the randomized Symplicity HTN-2 cohort, which included patients with true resistant hypertension. At baseline, mean systolic blood pressure in that study was 178 mm Hg. At 6 months following the procedure, pressure was reduced by an average of 32 mm Hg.

Improved Long-term Prognosis Key

The probabilities of such patients experiencing future cardiovascular and other adverse events were calculated based on multivariate risk equations from the Framingham study and other large epidemiological studies. Over a decade, renal denervation was projected to reduce the risk of stroke by 30%, MI by 32%, end-stage renal disease by 28%, cardiovascular mortality by 30%, and all-cause mortality by 15% compared with medical therapy.

Projected over a lifetime, risk reductions were less pronounced, but median survival increased by 1.30 years and quality-adjusted life expectancy by 1.10 years (table 1).

 Table 1. Clinical Risk Over a Lifetime

Abbreviation: QALY, quality-adjusted life years.

Although over a lifetime renal denervation reduced undiscounted costs by $1,769, it increased discounted costs by $2,013. The discounted lifetime incremental cost-effectiveness ratios were $2,715 per life year gained and $3,071 per QALY.

 The only variables found to have a significant impact on the incremental cost-effectiveness ratio were baseline systolic blood pressure, the magnitude of its reduction, and the cost of renal denervation.

Cost-effectiveness Maintained for Most Scenarios

The investigators put the cost-effectiveness of renal denervation to the test under various scenarios. Exploratory analysis determined that the incremental cost-effectiveness ratio would exceed the conventional societal willingness-to-pay threshold of $50,000 per QALY only if the systolic blood pressure reduction was assumed to be no more than 11.1 mm Hg.

In addition, the authors note, although 3-year follow-up of the Symplicity HTN-1 study suggests that blood pressure reductions will be sustained, an indefinite effect cannot, in fact, be assumed. However, additional analysis showed that the trial-based systolic reduction would need to decline by more than 3.0 mm Hg per year for the incremental cost-effectiveness ratio to exceed the $50,000 threshold. Even factoring in up to 3 repeat denervation procedures, 1 every 10 years, would push the incremental cost-effectiveness ratio only to $19,869 per QALY. In 21% of such simulations, renal denervation actually decreased costs, while overall there was a 99.6% probability that the incremental cost-effectiveness ratio would come in under the $50,000 per QALY threshold.

The authors acknowledge that the relative clinical outcomes predicted by the model would likely vary across groups with different risk profiles. However, they note, “plausible alternative assumptions did not substantially alter model projections.”

Dr. Pietzsch and colleagues acknowledge that the model harbors a number of limitations. For example, because experience with renal denervation is modest, adverse events that might occur after the procedure may not have been identified. Moreover, most patients in the trial cohort were Caucasian, and hypertension is known to contribute about 15% to the difference in life expectancy between African-Americans and Caucasians. Furthermore, the model was unable to include all possible pathological consequences of chronic hypertension. Finally, the findings may not be applicable to renal denervation systems other than Symplicity.

 Clinical, Economic Burden of Hypertension Highlighted

“Overall this is a reasonable attempt to understand the cost-effectiveness of a therapy that treats a condition where the benefits are far off in the future,” David J. Cohen, MD, MSc, of Saint Luke’s Mid America Heart Institute (Kansas City, MO), told TCTMD in a telephone interview.

The study relies on modeling and as such the results are entirely dependent on the assumptions made, he observed. “And by far the biggest assumption is that reducing blood pressure yields the risk reductions that are predicted by the epidemiological studies used,” he added, noting that the projection of more than an additional year in life expectancy is “quite a large benefit.”

“We have to recognize that this is a hypothetical study without any real-world evidence that it actually does what we think it might,” Dr. Cohen cautioned. Nonetheless, it is helpful because it lays out the serious clinical consequences of refractory hypertension, he commented, adding that “most cardiologists don’t really have a good sense of the tremendous clinical and economic burden that very severe hypertension exacts, and this is a good way of putting that into context.”

“It goes without saying that this result applies only to patients who are in the extreme group of refractory hypertension,” Dr. Cohen observed, noting that if renal denervation begins to be applied in a broader range of patients with less severe hypertension, its cost-effectiveness would have to be reassessed.

It will be interesting to see how payers react to this type of information once the therapy is approved,” Dr. Cohen commented. “These days, many payers still want to see clinical benefit [rather than projections]. Here all the benefits are years away, and unfortunately, given the way the health care system works in the United States, many payers have a much more limited time horizon.”

Study Details

On average, patients were on 5 antihypertensive medications and had a mean age of 58 years. Roughly one-third (34%) had diabetes and 16% were smokers. Assumed lipid levels were based on those of patients with uncontrolled blood pressure in the National Health and Nutrition Examination Survey (LDL 108 mg/dL, HDL 53 mg/dL, and total cholesterol 199 mg/dL).

Cost estimates were converted to 2010 US dollars and discounted 3% per year. The 1-time cost of renal denervation was estimated to be $12,500

Source:

Geisler BP, Egan BM, Cohen JT, et al. Cost-effectiveness and clinical effectiveness of catheter-based renal denervation for resistant hypertension. J Am Coll Cardiol. 2012;Epub ahead of print.

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