 However, there is evidence for the efficacy of EPD in the treatment of hay fever and other conditions as a result of nine placebo-controlled, double-blind trials involving 271 patients.These trials showed a significant improvement in the symptoms with probabilities of 0.001 to 0.01 (a chance of one in a thousand to one in a hundred that the results of the trial would be seen by chance alone assuming EPD had no effect).However, one trial involving 183 patients published in the British Medical Journal showed no overall effect.