Wednesday, December 21, 2011

What is lacking in fibromyalgia studies on drugs?

I think it’s a discussion on reasons for the observed (small) effects. It may be a bias that comes into effect before people come to enter a study. I see different patients: drug seeker, drug takers, drug avoiders, drug deniers, compensation seekers, non compensation seekers, depressed avoiders, happy sustainers, and patients who fit more categories if you like. I think that motivation for or against a therapy effects outcome. Currents studies do not address this issue. If you have a larger number of drug seekers coming to your drug testing center and a small number of drug avoiders of drug deniers, you might get a wishful thinking effect, a self fulfilling prophecy.

But wait a minute; we’ve got our placebo group! Look at the study of LJ Crofford et al. on Pregabalin in Fibromyalgia (Arthritis Rheum 2005, 52: 1264-1273), an eight week, randomized, double-blind, placebo-controlled, monotherapy dose-finding study. A reduction of pain greater than 50% compared to baseline has been primary endpoint of the study. This has been achieved in 13,2% of the placebo group, 13% in the 150 mg group, 18,9% in the 300 mg group, and 28,9% of the 450 mg group. Now let’s have a closer look at one of all the possible side effects: dizziness. Dizziness was complained in 15% of the placebo group, 30% in the 150 mg group, 42% in the 300 mg group, and 65% of the 450 mg group. So side effects aren’t matched! If patients desperately seek to get rid of their pains, this has an effect on quality of life, they cling to every straw. If you take a drug and notice that it’s doing something to you like dizziness, would you not also expect that it relieves your pain?

Drug studies in fibromyalgia patients should tell more about the motivation of patients to different therapies. A statistical analysis taking different levels of side effects into account should be established in these studies.

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