Novel procedure- and device-based strategies in the management of systemic hypertension

The data on the effectiveness of the carotid baroreceptor stimulator (Rheos system) in patients with resistant hypertension are still scanty (1 -3). Although this crucial information is lacking, the value-for-money of this device has been investigated in a preliminary report (4) in which the cost-effectiveness ratio was calculated to be in the "grey area" between interventions with a favorable profile and those with an unfavorable one.

In this framework, deciding whether the current acquisition cost for this device is acceptable or unacceptable is likely to translate into different decisions made by different hospitals in that some hospitals will decide to purchase this device, others will not, while others will try to negotiate a price rebate. This heterogeneity does not facilitate the access to this device for different patient populations.

In cases where the effectiveness of an innovative intervention is supported by limited information, the payment-by-results approach (or "satisfaction guaranteed" approach) is an efficient tool for handling the economic consequences of this uncertainty (5-8). In its most frequent implementation (6-8), the payment-by-results approach is applied by initially paying at their full price all devices that are implanted and by establishing a payback for the subgroup of patients who show an unfavorable outcome; this payback, which goes from the manufacturer to the third-payer payer, covers in most cases the full acquisition cost. Hence, successful cases are paid at full price while unsuccessful cases are paid none. Outcomes included in this procedure should be binary, i.e. classified as either success or failure with no intermediate choices.

Given the characteristics of the Rheos system, the payment-by-results approach could facilitate the access to this device, but the above- mentioned methodological constraint (binary classification of outcomes into success or failure) implies that one should define what a "success" is for this device.

According to the base-case analysis of Young et al. (4), lowering systolic blood pressure at 6 months by at least 24 mmHg (from a baseline of 180 mmHg) can be considered a success. In more general terms, as suggested by the ongoing clinical trials (1,2), a successful outcome could appropriately be defined as a percent decrease in systolic blood pressure by at least 15% at 6 months in comparison with the pre-implantation value; a decrease of less than 15% should instead be considered a treatment failure.

If the latter definition of success is accepted, applying the payment -by-results approach to the Rheos system becomes a very straightforward task: a full payback of the device cost for patients would in fact be required for all patients who are not successful at 6 months according to the above criterion.

One practical advantage is that the information governing the payback will always be available for these patients because outcome measurement at 6 months is mandatory. The next question is whether the manufacturer is willing to accept this payment scheme, but of course we ignore the answer to this question.

References

1. Lovett EG, Schafer J, Kaufman CL. Chronic baroreflex activation by the Rheos system: an overview of results from European and North American feasibility studies. Conf Proc IEEE Eng Med Biol Soc. 2009;2009:4626-30.

2. Scheffers I, Schmidli J, Kroon AA, et al. Sustained blood pressure reduction by baroreflex hypertension therapy with a chronically implanted system: Long-term data from the Rheos DEBuTHT study in patients with resistant hypertension. Journal of Hypertension 2007;25 (Suppl 2):S141.

3. Krum H, Schlaich M, Sobotka P, Scheffers I, Kroon AA, Peter W. de Leeuw PW. Novel procedure- and device-based strategies in the management of systemic hypertension Eur Heart J (2011) 32(5): 537-544

4. Young KC, Teeters JC, Benesch CG, Bisognano JD, Illig KA. Cost- effectiveness of treating resistant hypertension with an implantable carotid body stimulator. J Clin Hypertens (Greenwich). 2009 Oct;11(10):555 -63.

5. Garber AM, McClellan MB. Satisfaction guaranteed--"payment by results" for biologic agents. N Engl J Med. 2007 Oct 18;357(16):1575-7.

6. Lucioni C, Mazzi SF, Polcaro F. Il risk sharing come applicazione del value based pricing. PharmacoEconomics--Italian Research Articles 2010;12 (2):71-80.

7. Messori A, Trippoli S, Bonacchi M, Sani G. Left ventricular assist device as destination therapy: application of the payment-by-results approach for the device reimbursement. J Thorac Cardiovasc Surg. 2009 Aug;138(2):480-5.

8. Messori A, Trippoli S, Innocenti M, Morfini M. Risk-sharing approach for managing factor VIIa reimbursement in haemophilia patients with inhibitors. Haemophilia. 2010 May;16(3):548-50.

9. Messori A. MS risk sharing scheme. Outcome based schemes are more common than you think. BMJ. 2010 Jul 7;341:c3588

Conflict of Interest:

None declared

The technique of denervation by means of 4-5 RF ablations performed with stepwise rotation of the catheter without any specific orientation of the ablations to the front/back of the artery is obviously based on underlying assumption of renal nerves as a network of small fibers covering renal artery circumferentially like a basket from aorta to segmental branching. Then full circumferential coverage of RF lesions is necessary to completely disrupt conduction through such a basket. This view of renal nerves anatomy is so common that seems never been questioned in the first place. In fact, however, it may be nothing more than common belief because there is strong evidence against this view coming from the studies of open renal denervation. This almost forgotten today treatment was effectively used to relieve chronic flank pain associated with non-obstructive hydronephrosis. Unlike frequently mentioned splanchectomy involving nonselective removal of sympathetic elements in the upper abdomen, this method was focused exclusively on renal nerves. It has been suggested that distension of renal pelvis responsible for chronic pain is caused by excessive constriction of the pelvic/ureter sphincters due to hyperactivity of renal sympathetic nerves. To selectively block sympathetic input to the musculature of renal pelvis and ureter distal excision of renal nerves seemed the best option. Operational technique included creating access to the kidney pedicle, stripping fat, separating renal nerves from the renal artery and removing their distal parts before the artery branching. A substantial number of such operations were performed by various surgeons in 20-50th years of XX century. In 1950 J. B. Oldham presented summary data from his study including 88 cases. He reported anatomy of renal nerves as follows: numerous small roots comes from the semilunar, superior mesenteric, and aortico-renal ganglia, direct from the lesser splanchnic and from the least splanchnic nerve, if it is present, and occasionally direct from the greater splanchnic. The various roots ... are collected together in three bundles - superior, inferior, and posterior. The superior renal nerves-the largest bundle-consist of eight to ten nerves .... They are at first about one centimeter above the renal artery, towards which they run obliquely downwards and outwards joining it usually over its outer third on the right side and over its middle on the left side ... It should be noted that the renal nerves do not form a network around the artery, but run parallel to it and that there are no fibers running along the front of the artery .... These data from Dr. Oldham seem to directly reject the hypothesis of renal nerves as a basket of small fibers around renal artery. Then technique of full circumferential coverage of RF applications may be anatomically inadequate and need appropriate correction, e.g. ablations should be done precisely against superior, posterior and inferior arterial walls with no ablation of anterior wall at all, no superior and posterior ablations in proximal third of renal artery.

Conflict of Interest:

None declared