Cost effectiveness of sildenafil calls for political discussion

EDITOR—Freemantle comments on our analysis of the cost effectiveness of sildenafil. 1 2 He argues that the validity of quality adjusted life year (QALY) measures is based on strong assumptions and the measures are therefore insufficient for political decision making. Given that our analysis takes a conservative approach towards the cost effectiveness of sildenafil, however, these arguments cannot affect the conclusion that sildenafil is a highly cost effective drug.

Freemantle recognises the assumptions of classical welfare theory on which QALY analyses can be based. This is not the only interpretation of QALYs. There is the extra-welfarist approach, in which QALYs are a measure of health gain, not just a decision rule, and they simply quantify health, but the distribution of health—for example, QALYs—is based on a different set of rules. Freemantle assumes incorrectly that two patients who gain 0.5 QALYs are always valued equal to one patient who gains 1.0 QALY. In practice, additional distribution rules could favour one of the two patient groups. In this way, solidarity with those who are worst off could influence the distribution of health gains expressed in QALY terms.

His second criticism is that it would be more appropriate to use patients' values. This is not recommended in the usual guidelines of health economics. Nevertheless, we shared his concern whether the general public could imagine being affected with erectile dysfunction. We have also collected patients' values (available at http://www.imta.nl/). This report shows that according to the patients the quality of life gain attributable to sildenafil is larger than it is according to the general public. Thus, the cost effectiveness of sildenafil would be even more favourable using patients' values.

Whenever assumptions had to be made in our analysis, we chose the least favourable assumption for sildenafil. We also assumed that the effects of injection treatment would be as favourable as the effects of sildenafil, which they are not, given the invasive method of administration. It is therefore likely that when more data become available the conclusions will change in favour of sildenafil. This means that methodological flaws cannot affect the conclusion that sildenafil is a highly cost effective drug.

Perhaps the reservation of Freemantle towards the favourable cost effectiveness of sildenafil originates from his political and ethical thoughts. We disapprove of making political arguments technical ones. The discussion should be clarified instead of technically mystified. Sildenafil is a cost effective drug. The challenge is now to develop a decision making framework in which economic considerations are used besides ethical, distributional, or political arguments.