Correspondence issued by the Government Accountability Office with an abstract that begins "Overall, orthopedic IMD admission rates were substantially higher in 2009 compared with 2003, while admission rate patterns among cardiac IMDs were mixed. Admission rates rose for each of the orthopedic IMDs in our study, with knee replacement rates growing 6.7 percent per year. The picture for inpatient cardiac IMD procedures was more mixed; admission rates for dual-chamber pacemakers decreased steadily while rates for AICDs and drug-eluting stents increased through 2006 and generally declined thereafter, in part reflecting a shift of surgeries to the outpatient setting. While the proportion of both orthopedic and cardiac IMD beneficiaries in poor or very poor health grew throughout our period of study, this trend was far more evident for cardiac IMD beneficiaries after 2007."