Data Analysis
Study data were collected and managed using REDCap electronic data
capture tools hosted at Lenox Hill Hospital (17). REDCap (Research
Electronic Data Capture) is a secure, web-based application designed to
support data capture for research studies.
Observed covariates at baseline included age, gender, body mass index,
diabetes mellitus, cerebrovascular disease, chronic lung disease,
peripheral vascular disease, dialysis-dependent renal failure, history
of prior myocardial infarction, congestive heart failure, and left
ventricular ejection fraction. To control for these confounding
influences, we calculated propensity scores (or the probability of
assignment to HCR, CABG, or multi-vessel PCI) using multivariable
logistic regression for each patient. Patients who underwent HCR were
matched with patients who underwent conventional CABG and with those who
had multi-vessel PCI in a 1:1 ratio through a nearest neighbor-matching
algorithm. In order to exclude bad matches, we instituted a caliper of
0.2 of the standard deviation of the logit of the propensity score. The
Area Under the Curve for the ROC of the propensity model 0.74. The
matched sample included a total of 300 patients, evenly distributed in
each group
Longitudinal outcomes and survival to 8 years was estimated using
Kaplan-Meier analysis and Cox proportional hazard regression. Patient
characteristics and outcomes were compared using chi-square, Fisher’s
exact test, Student’s t-test, or Wilcoxon-Mann-Whitney test, as
appropriate. A chi-square test was used for categorical variables where
the expected value for each cell was 5 or higher; if this assumption was
not met, then Fisher’s exact test was used. A p value of less
than 0.05 was considered to be statistically significant. Statistical
analyses were performed with the IBM Statistical Package for the Social
Sciences (SPSS) for Windows, version 22.0 (IBM Corporation, Armonk, NY,
USA).
Mean (± SEM) follow-up was 7.14 ± 0.12 years for all patients. All-cause
mortality up to a maximum of 8 years was obtained by querying the
National Death Index (NDI) to determine dates of death up to December
31, 2016. Short-term outcomes, such as length of hospital stay,
peri-procedural stroke, myocardial infarction (MI) or new-onset renal
failure was evaluated via a retrospective chart review on our hospital
systems electronic medical records. The long-term follow up for repeat
revascularization, myocardial infarction and target vessel
revascularization was achieved through a chart review of our hospital
system and our referring hospital systems electronic medical records.
The majority of patients had follow up greater than 1 year, however
there were patients (18 total) that we were unable to find proper
follow-up after hospital discharge.