Medical science has learned a great deal about the causes of pain and ways to relieve it, pain experts say, but for a host of reasons, the treatment of pain and suffering has improved hardly at all in recent years. Hospitals do a little better than that in managing pain for patients with all kinds of illnesses, according to a survey in the New England Journal of Medicine.The survey of hospitals in 40 metropolitan areas by the Harvard School of Public Health found that one-third of patients felt that their pain wasn't well controlled. The percentage of those who were satisfied by their pain care ranged from 72% in Birmingham, AL, to 57% in New York City hospitals.