PTO1 trade-off equivalent
PTO2 trade-off equivalent
Trade-off equivalents in PTO
and PTO2 methods for
disability weights of a selected
number of severity levels
Summary Measures of Population Health
0.005 0.01 0.02 0.45 0.50
quence when applied in a burden of disease calculation this also means a doubling of the DALY estimate for that condition.
This is a recognized problem of the current valuation methods for which no alternative has yet been developed and tested. It is therefore not a wise practice to put relatively severe conditions of short duration, such as myocardial infarction and pneumonia, artificially into a low-severity cat- egory by presenting them as an annual profile.
From comparisons of burden of disease results between different set- tings and time periods, it is desirable that disability weights relate to health states in their “purest” form and that variations in numbers of cases and durations drive the differentials in the calculations. Stipulating a duration in the description of conditions for which weights are derived reduces their applicability to making these comparisons. To illustrate this point, let us look at peptic ulcer disease. The Dutch study valued this health state as an annual profile with four weeks of peptic ulcer disease in an otherwise healthy year. If an intervention becomes available that reduces the aver- age duration to three weeks, a new weight would have to be generated for a profile of one year with three weeks of peptic ulcer disease unless the true weight for the symptomatic period is back-calculated from the annu- alized weight. We have seen above that this did not give very credible results. The simple solution to this problem is to keep duration out of the description of disease states for which disability weights are generated. Any changes in the duration of the condition can then be driven by the epide- miological findings.
It becomes even messier when annual profiles are valued for a combi- nation of a short duration condition followed by a chronic complication. Let us take acute myocardial infarction (AMI) and heart failure as an example. An annual profile would be, say, six weeks of AMI followed by heart failure for the rest of the year. You would also need to have a sepa- rate weight for AMI not followed by heart failure and another weight for heart failure for those who continue to have heart failure past the first year. If these three are valued separately it is more than likely that the compos- ite weight for AMI + heart failure will differ from six weeks at the weight for AMI alone and 46 weeks with heart failure. That would be an unten- able position unless you want to argue that heart failure in the 46 weeks