Study Population
From 2011 to 2017, a total of 43,077,206 discharge records comprised the NIS for the US adult population (age 18 years or above), corresponding to a national estimate of 214,107,782 hospitalizations across the country. We identified all patients aged 18 years or older undergoing LVAD implantation using ICD-9-PCS code 37.66 and ICD-10-PCS code 02HA0QZ in any procedure field. Our final study cohort comprised 5,131 patients undergoing LVAD implantation, corresponding to a weighted estimate of 25,503 overall LVAD implantations during this time period. This estimate was calculated by using discharge weights provided with the NIS files. The study population was reflective of the one device era—the continuous flow (CF) device based on the US Food and Drug Administration approval of CF devices in 2008. ICD-9-CM/PCS and ICD-10-CM/PCS coding for comorbidities, post-LVAD complications and other procedures is listed in Table I in the Data Supplement.