There are huge numbers of markedly obese patients in the US. While I have seen little literature on this topic, I am acutely aware of in my own practice is the lack of data on treating the morbidly obese.
For example, a weight >300 pounds is a common exclusion on many clinical trials. The result is that there is little evidence-based medicine, and considerable problem knowing how to dose patients with a variety of medications. Little pharmacokinetic or pharmacodynamic information is available, and much of that is limited to healthy volunteers. Accurate physical examination is near impossible at times. Many patients are too obese to have diagnostic imaging studies, especially CAT scans or MRI scans, reducing us, it seems, to veterinary medicine. There are various recipes for drug dosing in obese patients—some based on ideal body weight (IBW), some on actual body weight, or some based on witchcraft (somewhere in the middle between IBW plus a percentage of the excess weight). The concern about the lack of evidence is particularly timely now, given that serious illness and deaths from Influenza A H1N1 are disproportionately affecting the obese. Some studies are proposed, as Oseltamivir Pharmacokinetics in Morbid Obesity (OPTIMO), but are just getting started (November 2009). Given the unfortunate change in patient demographics in the US and the epidemic of obesity here, clinical trials focusing on this population would be timely and most welcome.