Methods
The data for this project was obtained from the AHRQ (Agency for
Healthcare Research and Quality) HCUP (Healthcare Cost and Utilization
Project) Nationwide/National Inpatient Sample (NIS) for the years
2010-2015. This is the largest all-payer database in the United States
covering about 20% of all hospitalizations in the acute care community
hospitals that is up to 8 million for each year. The detailed
information about the elements of the NIS database is available athttps://www.hcup-us.ahrq.gov/db/nation/nis/nisdbdocumentation.jsp.
The study population included patients aged ≥70 years old who were
hospitalized for coronary artery disease (CAD) and underwent CABG during
seven days after hospitalization. To select these patients, we used the
ICD-9-CM (International Classification of Diseases, Ninth Revision, and
Clinical Modification) diagnosis codes 41001, 41011, 41021, 41031,
41041, 41051, 41061, 41071, 41081, 41091. The ICD code for CAD is 41401,
and CCS code for CABG is 44. The ICD and CCS code was used for the
principal diagnosis to limit the sample to patients aged 70-89 years old
who were electively (ELECTIVE=1) or non-electively (ELECTIVE=0)
hospitalized for MI (initial episode) or CAD (principal diagnosis for
both) and underwent CABG (any procedure position) during 7 days after
hospitalization.
Demographic information was collected for each patient. Pre-, intra-,
and post-operative findings were identified through a thorough review of
the data. Postoperative complications, morbidity, and survival
information were also reviewed. Patients that are ≥70 years who
underwent CABG were selected from the Nationwide/National Inpatient
Sample from 2010 to 2015 using ICD-9-CM diagnosis and procedure codes.
The patients who were ≥70–79 years old were compared to patients aged
≥80–89 years old to determine if the age difference of the patients had
an impact on surgical outcomes. In addition, the gender of the patients
80-89 years old were compared to determine the influence of patient
gender on surgical outcomes. The rates of postoperative complications,
mortality, hospital length of stay (LOS) and cost were compared using
the Chi-square test, multivariable logistic regression analysis, and
Wilcoxon rank sum test.