The U.S. Preventative Services Task Force (USPSTF) is an independent panel of private-sector experts in primary care and prevention. The Task Force was convened by the U.S. Public Health Service to systematically review the evidence of effectiveness of clinical preventive services. One of their charges was to evaluate the evidence supporting the practice of school screening for adolescent idiopathic scoliosis. After systematically reviewing the literature to date, their policy statement issues in 1992, and updated in 1996 states "…There is inadequate evidence to determine whether brace therapy limits the natural progression of the disease in a significant proportion of cases, as most studies suffer from selection bias, lack of internal control groups, inadequate follow-up, small sample sizes, and lack of health outcome measures."