In the APRIL 07 edition of Arthritis and Rheumatism Arnold et al publish the good news that gabapentin (neurontin) improves the well being of fibromyalgia patients. This follows previous studies such as the pregabalin (lyrica) study from 2005 that also show that improvement of up to 50% is possible. It's great news, of course, but leads to the question: Why don't my patients get better? In fact, why do their placebo patients do better than my own treated patients?
Maybe the answer is in the details. In their study patients were given up to 2400 mg of neurontin, with a median of 1800mg. Despite these doses, 57 of 75 patients were able to finish the 12 wk study, only 12 withdrawing because of adverse effects. This despite the fact that about 25% had each of headaches, dizziness, and sedation. By study's end, 51% of the treated patients had noted the target of 30% improvement. Of the placebo group, 31% attained this level.
The placebo results are rather bothersome and seems to plague several fibromyalgia studies. An interesting paper back in 2004 byHrobjartsson and Gotzsche discussed placebos, claiming that when compared to no-treatment groups, placebos generally have no effect, unlike the common wisdom. The interesting exception, however, was in pain studies where there was a small but real difference. They claimed it was unlikely a placebo effect, but rather report bias, suggesting that these patients may be reporting improvement when none really exists. This may well be the case in our fibromyalgia studies, with all patients being overly optimistic, or trying to help out these researchers who are finally doing something for them. That said, the treated groups do fair better than the placebo groups and so I have not yet explained my own treatment failures. One may be the exclusions. All patients had to be able to wash out antidepressants and other meds with CNS effects. There is also the peculiar exclusion of "patients who, in the opinion of the investigator, were treatment refractory". So maybe they just have a much less serious group. Maybe they've excluded everybody who failed other treatments like cyclobenzaprine and amitriptyline. The other possibility is the doses they gave. Short of a dart gun I don't see how I would get my patients to take the doses they attained. What kind of persuasion did they use to keep 57 drowsy, headachy, lightheaded, nauseous achy people going for 12 weeks. And more importantly, how many of these patients chose to continue on after the study.
So I'm not convinced, but that doesn't mean I won't give it a try. I might try neurontin first-line, rather than down-the-line. I'll try to get them off some of their other meds, maybe that will increase tolerability. I'll show them this study, maybe they will be able to tough it out longer with something down in black and white. Hopefully, then, I'll see at least the occasional success that research suggests is out there.