Strengths and Limitations
Utilization of the NIS provides us with an opportunity to analyze a
large number of LVAD patients, from hundreds of nationwide centers,
across a 7-year timeframe (weighted estimate of 25,503 LVAD implants).
However, as NIS represents hospitalizations and not individual patients,
there is a possibility that patients undergoing pump exchanges may
feature more than once in the data set. Our analyses are also limited by
a lack of longitudinal follow-up and are valid for a short-term period
(~10–70 days as suggested by mean ± standard deviation
LOS). The inability of NIS to define the proportion of individuals
eligible for LVAD implantation despite income, as opposed to the
proportion who ultimately undergo LVAD implantation, is important.
Lastly, with the NIS, we are unable to assess echocardiographic findings
that might affect the eligibility or feasibility of LVAD, laboratories
data which is critical for patients undergoing LVAD and the severity of
advanced heart failure assessed by INTERMACS score of patients
undergoing LVAD implantation. Prospective studies of income differences
in patients with advanced heart failure are needed to confirm whether
such differences may exist.