Pray get better
One of the basic difficulties of doing any medical study is something that's known to speakers of Epidemiologese as exposure measurement. If you're conducting research on the effect of gamma rays on man-in-the-moon marigolds, you need to measure your gamma rays. If you want to find out if fried chicken causes cancer, you either need to (a) trust the subject to faithfully record each and every visit to Popeye's; (b) somehow spy on them at home and on the way, with their consent; or (c) lock them in a room, provide them with food, and spy on them through a mirror. (All of these have been tried.) Dietary epidemiology is the black hole of untestable hypotheses, precisely because it's so hard to determine what people actually eat and when.
If exposure measurement is tough for dietary studies, for which there are no lack of biologically plausible hypotheses, you can imagine the signs I would put up around the scientific minefield called Prayer and Health. For in this case, the methodological difficulties are intimately bound up with the theological ones. How does one define prayer? When is prayer "properly" done? What is the hypothesized mechanism of prayer? These are not merely matters of idle theological speculation, but questions that must be answered before any study gets off the ground. I haven't read many studies on this topic, only a few -- but those few not only failed to fly: they staggered a few steps and fell flat on their bellies. That's why it's so refreshing to read a critic on the subject sympathetically interviewed by the lay press. He perceptively points out that a misguided attempt to introduce "prayer" (however one might define it) into the standard of medical care might actually pervert both medical practice and religious observance, in the same way that theocracy works neither as religion nor as politics.
I particularly admired the interviewee's stalwart refusal to respond to the question, "Are you a religious person?" This is irrelevant to the topic at hand. Religious people, just like scientists, should be properly skeptical of implausible claims. True religious observance does not imply or require credulous acceptance of every claim on behalf of prayer, nor does it depend on dubious, pseudo-scientific validation of these claims.