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06/07/2012

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Daniel S. Goldberg

Marvelous.

I had a different criticism of that 2008 paper when I read it. Namely, I entirely disagree with how they operationalized "prevention" in the study, because the notion of prevention they used was pretty obviously preventive medicine, as opposed to primordial, population-health rooted prevention. This reflects the capture of prevention by medical services (see Starfield's nice work on this), which skews any subsequent analysis because the evidence base for health outcomes are quite different for prevention that is more proximal to disease (and is much closer to the delivery of acute health care services) than primordial prevention that addresses much more distal factors.

So even if their analysis was entirely methodologically sound, it used entirely the wrong concept of prevention.

But your criticism is much cooler.

Brad F

Bill
I am not following here.

If Tx is already embedded in system (the key), and Tx* comes online, yes, it touches fewer lives, but the QALY we are buying off the base is identically priced as the step up in the Px to Px* example. The only difference is the larger investment and the more folks intervened upon in the preventative strategy.

Bottom line, that incremental QALY is still costing 10K per person. If you only had a 100K to spend, no matter where you apply it--T vs P, you add 10 QALYs.

Brad

Bill Gardner (@Bill_Gardner)

Hi Brad,
Interesting comment, but this is Paul's argument. I will be interested in his response.
Bill

Paul

Hi Brad,

One of the points I'm making is that the incremental cost-effectiveness ratios (ICER) are not fined grained enough to support the inferences you make here. For example, if Tx and Px are already being funded, and we then come into $10k more dollars, then it is not necessarily true that we can use that $10k to buy an extra QALY with both Tx* and Px*. After all, transforming Px into Px* requires a jump from screening 20% of the population to 90% of the population, and we won't be able to effect this jump with just $10k.

What this means is that *if* Tx and Px are already up and running, and *if* we are not allowed to reallocate funds from Tx to Px/Px*, and *if* we have $10k extra to spend, then we should spend that extra on transforming Tx to Tx* (since we know we can transform Tx into Tx* with the extra $10k).

However, if we *are* allowed to reallocate funds away from currently funded programs, then the arrangement that maximizes QALYs is the one that *defunds* Tx and uses those funds (i.e. the $4.5 million) to transform Px into Px*. The problem, I submit, is that you cannot know that this is the way to maximize QALYs by just looking at the ICERs of Tx* and Px*. If you go on ICERs alone, then Tx* and Px* can seem equally cost-effective. But they are not equally cost-effective: you get hundreds more QALYs by abandoning Tx and Tx* and putting all your funds into Px*.

Brad F

Paul
Point taken, but its not about P vs T, but the broader analysis you are calling for. The fixed costs needed to implement a P program may supersede that of a T--to the point of making it prohibitive.

Your post is cautionary and needed, but the issues you raise may not have been lost on the author's. They were contrasting cost-effectiveness only. My point was a QALY is a QALY, and as a metric, has a flattening effect for comparative purposes. The infrastructure required to make them happen is another ball of wax.

Brad

Paul

Hi Brad,

I'm not following. I am assuming that fixed costs are included in total costs. Tx and Px are already funded. The question is, what do we do now if we wish to maximize QALYs with our fixed budget? The authors suggest that so long as Tx* and Px* have the same ICERs, then they provide equally good avenues for maximizing QALYs (see the passage I quoted from them). But this might not be so if we have the option of defunding Tx and using its budget ($4.5 million) to expand Px into Px*. In my example, that is unequivocably the avenue that maximizes QALYs; but it's not an avenue we would ever think about if we just restricted our decision-making to those interventions that have the lowest *incremental* cost-per-QALY. And this is because a new program can have a low incremental ratio and yet a high total ratio (total costs divided by total QALYs). This can happen when the currently funded program is itself not very cost-effective, as in the case of Tx.

Does that make sense?

Brad F

When I use the term fixed costs, I am referring to the gaps we are usually accustomed to in analyses, ie, have all the fixed costs been taken into account. FOr example, in a preventative intervention, have all the costs to local DOH, etc., been accounted for. Usually not. I assumed that is what you meant by comparing the two examples above--and the implication was that P was more efficient due to scale or other factors. I misunderstood.

I get your above point though, and where I/we departed was my inference that T is embedded in the system (you are not--and change is possible), which unfortunately is my linear view of the clinical world (I live there, my bias). Perhaps the authors are seeing it the same way.

Their position is, "this stuff is already here and in use, and accepting that, lets look at ICERs."

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