“…6,7 This may be especially important for elderly patients, for whom cardiac reoperation has been shown to carry a markedly higher risk of mortality and morbidity. [8][9][10] Furthermore, the NIS database relies on International Classification of Diseases, Ninth Revision and Healthcare Cost and Utilization Projection Clinical Classification Software codes to indicate outcomes. Events are not adjudicated, and no quality control measures for medical accuracy are implemented nationally or site-by-site by hospital audits.…”