A variety of bloodless surgical techniques have been developed for use on patients who refuse blood transfusions for reasons that include concern about AIDS, hepatitis, and other blood-borne infections, or immune system reactions.[31] Many physicians have expressed a willingness to respect patients' preferences and provide bloodless treatment[32][need quotation to verify] and about 200 hospitals offer bloodless medicine and surgery programs for patients who wish to avoid or limit blood transfusions.[32] Bloodless surgery has been successfully performed in significant procedures including open-heart surgery and total hip replacements.[33] A 2012 study in JAMA Internal Medicine concluded that "Witnesses do not appear to be at increased risk for surgical complications or long-term mortality when comparisons are properly made by transfusion status.