80 percent over the previous year, in favor of those made from other materials, such as combinations of metal and plastic. The cause of these failures remains controversial, and may include both design factors, operative technique factors, and factors related to patient immune response. In the United Kingdom, the Medicines and Healthcare products Regulatory Agency commenced an annual monitoring regime for metal-on-metal hip replacement patients from May 2010. Data which are shown in The Australian Orthopaedic Association's 2008 National Joint replacement registry, a record of nearly every hip implanted in that country over the previous 10 years, tracked 6,773 BHR (Birmingham Hip Resurfacing) hips and found that less than 0.33% may have been revised due to the patient's reaction to the metal component. Other, similar, metal-on-metal designs have not fared as well, with some reports showing that 76–100% of people with these metal-on-metal implants with aseptic implant failures and needing revision surgery also had histological evidence of inflammation, accompanied by extensive lymphocyte infiltrates characteristic of delayed-type hypersensitivity reactions. It is not clear to what extent this phenomenon negatively affects orthopedic implant patients. However, for patients presenting with signs of allergic reaction, testing for sensitivity should be conducted. Removal of the device should be considered, since removal may alleviate the symptoms. Patients who have allergic reactions to alloy jewelry are more likely to have reactions to orthopedic implants. There is increasing awareness of the phenomenon of metal sensitivity, and many surgeons now take this into account when planning which implant is optimal for each patient. On March 12, 2012, The Lancet published a study, based on data from the National Joint Registry of England and Wales, finding that metal-on-metal hip implants failed at much higher rates than other types of hip implants, and calling for a ban on all metal-on-metal hip prostheses. The analysis of 402,051 hip replacements showed that 6.2% of metal-on-metal hip implants had failed within five years, compared to 1.7% of metal-on-plastic and 2.3% of ceramic-on-ceramic hip implants. Each increase in head size of metal-on-metal hip implants was associated with a 2% increase in failure rate. Surgeons of the British Hip Society recommended that large head metal-on-metal implants should no longer be implanted. On February 10, 2011, the U.S. FDA issued an advisory on metal-on-metal hip implants, stating it was continuing to gather and review all available information about metal-on-metal hip systems. On June 27–28, 2012, an advisory