Data Source and Patient Population
We used the Healthcare Cost and Utilization Project (HCUP) Nationwide Readmission Database (NRD), a nationally representative sample of all-payer discharges from US nonfederal hospitals sponsored by the Agency for Healthcare Research and Quality (AHRQ). It includes discharge data with >100 clinical and nonclinical variables, including patient demographics, diagnoses, procedures performed, source of payment, total hospital charges, treating hospital characteristics, and readmission information with approximately 14 million cases. A retrospective study was performed using years 2013 to 2015 of the NRD for all patients undergoing either decompression and/or spinal fusion surgery for spinal metastases.
Patient demographic information, comorbidities, and treating hospital characteristics were collected. Demographic information included age, sex, median household income percentile, and primary expected payer (Medicare, Medicaid, private insurer, other). Hospital characteristics included teaching status (metropolitan teaching, metropolitan nonteaching, and nonmetropolitan), and hospital bed size (small, medium and large). Preexisting comorbidities were scored using the Elixhauser Comorbidity Index as computed by AHRQ. We included hypertension (HTN), diabetes, obesity, chronic pulmonary disease, depression, hypothyroidism, deficiency anemia, renal failure, other neurological disorders, congestive heart failure, rheumatoid arthritis/collagen vascular diseases, peripheral vascular disease, coagulopathy, liver disease, and alcohol abuse. Smoking status was also identified (305.1, 649, 989.84, V15.82). Complications and drivers for readmission ICD-9 CM codes used are found in Supplemental Data (SDC), https://links.lww.com/BRS/B699.
National estimates were calculated by applying discharge weights developed for the NRD before analysis. Descriptive statistics were summarized for patient demographic information, hospital characteristics, and comorbidities of the study cohort grouped by those with unplanned 30-day readmission, 31- to 90-day readmission, and no readmission (non-R) after decompression and/or stabilization surgery. All-payer inpatient cost-to-charge ratios were used to convert total hospital charge to total cost of admission. Parametric data were expressed by readmission groups as mean ± SD. Nonparametric data were expressed as median (interquartile range). Categorical variables were described using percentages. For the most common principle diagnoses among the readmission cohorts, proportions of 30- and 31- to 90-day readmission were described using percentages. Of note, all data elements reporting a patient count of <10 are indicated by "<10" given the reporting restrictions by HCUP.
Spine. 2021;46(12):828-835. © 2021 Lippincott Williams & Wilkins