A substantial body of evidence exists in support of chiropractic treatment. In the UK, a Medical Research Council study in 1990 suggested that improvement in back-pain patients treated with chiropractic treatment was greater than that of patients referred for hospital physiotherapy. In 1995, the UK's Clinical Standards Advisory Group recommended that the National Health Service refer more patients to practitioners specially trained in manipulation. In several US studies, chiropractic was found to be so effective in relieving acute back pain that its use for this condition was endorsed in 1994 by the Federal Agency for Health Care Policy and Research.