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What You May Learn From the Dutch Experience

Department of Medical Decision Making, Leiden University Medical Center, Leiden, the Netherlands

Cornelis J.H. van de Velde

Department of Surgery, Leiden University Medical Center, Leiden, the Netherlands

To the Editor:

In their discussion of our article¹ "Cost-utility analysis of preoperative radiotherapy in patients with rectal cancer undergoing total mesorectal excision,"Simunovic et al² raise some important issues related to cost-effectiveness analyses (CEAs) in general and to our study in particular. Since not all clinicians may be aware of the intricacies of CEAs, we would like to qualify those issues: the credibility of the survival difference, the generalizability of surgical quality, the international comparability of CEAs, and the usefulness of estimated cost-effectiveness (CE) ratios.

Concerning the credibility of the survival difference, an important goal of our study was to model to what extent a reduction in local recurrence rates could improve survival, since the Total Mesorectal Excision (TME) Trial was not designed and powered to prove or disprove a difference in survival. In other words, survival is a model outcome calculated from several model input parameters, in particular the recurrence rates for all health states. Not only is the sensitivity analysis on the 95% CI for the survival proportional hazard ratio suggested by Simunovic et al therefore impossible, but the more relevant sensitivity analyses are those involving the recurrence rates. The elaborate sensitivity analyses on recurrence rates have shown that the CE ratio remains acceptable under a wide range of circumstances. Moreover, we included a sensitivity analysis in which we maintained the difference in recurrence rates, but neutralized the estimated survival difference. Even in this biased analysis the gain in quality of life resulting from prevented recurrences outweighed the loss in quality of life due to preoperative radiotherapy (PRT), albeit less cost effectively so than in the base-case analysis.

Concerning the generalizability of surgical quality, we agree that the quality of surgery may vary, and thus the benefit and CE of PRT (see Fig 3 of our article). The patients included in our analysis were derived from 84 hospitals in the Netherlands, in which standardized quality-controlled TME surgery was implemented by an extensive structure of specialist surgeons, workshops, and videos.³ The local recurrence rate in the surgery-alone arm of the TME Trial is indeed higher than the recurrence rates quoted by Simunovic et al, but still, because of the large number of participating hospitals and surgeons in the TME Trial, those results may be more generalizable than the low recurrence rates achieved by few specialist surgeons. If, on the other hand, the surgical quality within the TME Trial would be unrealistically high, then this would only confirm the CE of PRT. Since lower-quality surgery would increase local recurrence rates, it would also increase the effectiveness of PRT without increasing the costs.

Concerning the international comparability of economic analyses, cost prices may indeed not always be exchanged between countries. There is no uniform standard for comparing prices between countries. Since there is no direct solution for the problem of international comparability, we have also included the mean volumes of health care utilization in Table 4 of our article. This allows the interested readers to attach their own national price tag to those volumes and determine the CE for their specific situation. An alternative to the exchange rate would have been to use the purchasing power parity (PPP). The PPP is a rate of currency conversion that aims to eliminate the difference in price levels between countries, but also has drawbacks (eg, the PPP differs between economic sectors), and for health care, it is difficult to calculate a reliable PPP.⁴ In 2002, the general PPP of health care for conversion of Dutch to American price levels was 1.05.⁵ The resulting CE ratio based on PPPs would have been $26,400/QALY (quality-adjusted life year), only a slight change as compared to the reported CE ratio of $25,100/QALY based on exchange rates. Furthermore we would like to stress that in the Netherlands the tariffs for bed-day prices are many times larger than the guideline cost prices we used in our analysis, but it is generally recognized that, especially for hospitalization, the tariffs are not a fair reflection of the real costs.

Concerning the usefulness of estimated CE ratios, Simunovic et al argue that it is the task of the researcher to determine not only the costs and benefits of treatments per patient, but also to determine the nationwide implications and the opportunity costs incurred by other patient groups. First, the impact on the health care budget is dependent on the number of patients treated in a specific country and can be derived easily from the costs and effectiveness per patient. Second, a researcher can only estimate opportunity costs if cost-effectiveness data were available for all potential health care interventions. This is a rather idealized picture, and CE analyses are therefore performed mostly for selected interventions that are controversial and may be potentially expensive. Data on cost effectiveness are then one of the many pieces of other information (ie, legal considerations, considerations of distributive justice) relevant for policy decisions concerning health care interventions that must be weighed. In our view, the ultimate responsibility for the distribution of health care resources lies with policy makers, who have received society’s mandate to do so. The task of the researcher is not to decide how to redirect resources, but to properly inform the policy maker whether a particular treatment provides value for the money.

In summary, we recognize that many assumptions used in CEAs are debatable, but we believe that our extensive sensitivity analyses show that our conclusions remain valid under a wide range of alternative assumptions. Therefore, from a societal perspective, economics should not be a reason to withhold PRT from these patients.

Authors' Disclosures of Potential Conflicts of Interest

The authors indicated no potential conflicts of interest.

REFERENCES

1. van den Brink M, van den Hout WB, Stiggelbout AM, et al: Cost-utility analysis of preoperative radiotherapy in patients with rectal cancer undergoing total mesorectal excision. J Clin Oncol 22 : 244 -253, 2004[Abstract/Free Full Text]

2. Simunovic M, Gafni A, Levine M: Economics of preoperative radiotherapy with total mesorectal excision: What can we learn from the Dutch experience? J Clin Oncol 22 : 217 -219, 2004[Free Full Text]

3. Kapiteijn E, van de Velde CJH: European trials with total mesorectal excision. Semin Surg Oncol 19 : 350 -357, 2000[CrossRef][Medline]

4. Organisation for Economic Co-operation and Development: Castle's report: Review of the Eurostat-OECD PPP programme 1997. http://www.oecd.org/dataoecd/33/15/2405262.pdf

5. Organisation for Economic Co-operation and Development: Purchasing Power Parities (PPPs) for OECD countries 1980-2003, 2/04 update. http://www.oecd.org/statisticsdata/

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• In Reply:
  Marko Simunovic, Amiram Gafni, and Mark Levine
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