[potatolicious]

I wonder if this will have unintended economic consequences. Clinical trials are astonishingly expensive - if we required all players to clinically test against competitors (or just the current leading competitor), it seems this would create a perverse incentive to be first to market. Not only would you rake in the early profits, but you'll also significant raise the bar for anyone trying to unseat you.

I'm not convinced this will actually be the case, but it's a possible outcome worth thinking about.

One thing I'm wondering: if all clinical studies are quantified via efficacy vs. a fixed placebo, shouldn't that make the results comparable? If Drug A is 200% more effective than a placebo, and Drug B is 300% more effective, does that not suggest that Drug B > Drug A?

[refurb]

Yes, it is possible to compare two placebo controlled trials and get a rough estimate of the relative efficacy of the two drugs. Many of the prescribing decisions that physicians make are based on these indirect comparisons.

However, it's only a rough estimate. Even if the patient populations are nearly identical, you can often see different outcomes.

To give you an example: Crohn's disease is an autoimmune disease of the large (and sometimes small) intestine. If you look at the clinical trials for the biologics used to treat the condition, you'll see remarkably varied outcomes, even in the placebo arm.

In other words, if drug A show 50% vs. 20% efficacy vs. placebo and drug B showed 70% vs. 40% efficacy vs. placebo, which is the more efficacious drug?

[roc]

> "drug A show 50% vs. 20% efficacy vs. placebo and drug B showed 70% vs. 40% efficacy vs. placebo"

Which raises a further (or more basic) confounding factor: the placebo effect isn't fixed.

It does vary between trials and even appears to be steadily increasing in potency over time. [1]

So first-to-market drugs have an added advantage when naively considering "improvement vs placebo" -- as their test were run years ago, when the placebo effect itself was a weaker opponent.

[1] http://www.wired.com/medtech/drugs/magazine/17-09/ff_placebo...

[pdpi]

> One thing I'm wondering: if all clinical studies are quantified via efficacy vs. a fixed placebo, shouldn't that make the results comparable? If Drug A is 200% more effective than a placebo, and Drug B is 300% more effective, does that not suggest that Drug B > Drug A?

I'm not sure that works. How do you account for different test conditions?

[shoyer]

Exactly -- the tests may have been done on different populations. In an extreme case, imagine both treatments are randomized trials for an otherwise terminal illness, but Drug A was tested on the elderly and Drug B was tested on youths. When cured, those on Drug B will live longer, if only because they are young.