title: Temporal variability of readmission determinants in postoperative vascular surgery patients.
abstract: BACKGROUND
  Clinical information continues to be limited regarding changes in the temporal risk profile for readmissions during the initial postoperative year in vascular surgery patients. We set out to describe the associations between demographics, clinical outcomes, comorbidity indices, and hospital readmissions in a sample of patients undergoing common extremity revascularization or dialysis access (ERDA) procedures. We hypothesized that factors independently associated with readmission will evolve from "short-term" to "long-term" determinants at 30-, 180-, and 360-day postoperative cutoff points.
  
  
  METHODS
  Following IRB approval, medical records of patients who underwent ERDA at two institutions were retrospectively reviewed between 2008 and 2014. Abstracted data included patient demographics, procedural characteristics, the American Society of Anesthesiologists score, Goldman Criteria for perioperative cardiac assessment, the Charlson comorbidity index, morbidity, mortality, and readmission (at 30-, 180-, and 360-days). Univariate analyses were performed for readmissions at each specified time point. Variables reaching statistical significance of P< 0.20 were included in multivariate analyses for factors independently associated with readmission.
  
  
  RESULTS
  A total of 450 of 744 patients who underwent ERDA with complete medical records were included. Patients underwent either an extremity revascularization (e.g. bypass or endarterectomy, 406/450) or a noncatheter dialysis access procedure (44/450). Sample characteristics included 262 (58.2%) females, mean age 61.4 ± 12.9 years, 63 (14%) emergent procedures, and median operative time 164 min. Median hospital length of stay (index admission) was 4 days. Cumulative readmission rates at 30-, 180-, and 360-day were 12%, 27%, and 35%, respectively. Corresponding mortality rates were 3%, 7%, and 9%. Key factors independently associated with 30-, 180-, and 360-day readmissions evolved over the study period from comorbidity and morbidity-related issues in the short-term to cardiovascular and graft patency issues in the long-term. Any earlier readmission elevated the risk of subsequent readmission.
  
  
  CONCLUSIONS
  We noted important patterns in the temporal behavior of hospital readmission risk in patients undergoing ERDA. Although factors independently associated with readmission were not surprising (e.g. comorbidity profile, cardiovascular status, and graft patency), the knowledge of temporal trends described in this study may help determine clinical risk profiles for individual patients and guide readmission reduction strategies. These considerations will be increasingly important in the evolving paradigm of value-based healthcare.
authors.affiliation: Department of Surgery, St. Luke's University Health Network, Bethlehem, PA, USA.
authors.forename: M J
authors.initials: MJ
authors.lastname: Lin
authors.affiliation: Department of Surgery, The Ohio State University College of Medicine, Columbus, OH, USA.
authors.forename: F
authors.initials: F
authors.lastname: Baky
authors.affiliation: Department of Surgery, The Ohio State University College of Medicine, Columbus, OH, USA.
authors.forename: B C
authors.initials: BC
authors.lastname: Housley
authors.affiliation: Department of Surgery, The Ohio State University College of Medicine, Columbus, OH, USA.
authors.forename: N
authors.initials: N
authors.lastname: Kelly
authors.affiliation: Temple University School of Medicine - St. Luke's University Hospital Campus, Bethlehem, PA, USA.
authors.forename: E
authors.initials: E
authors.lastname: Pletcher
authors.affiliation: Department of Surgery, St. Luke's University Health Network, Bethlehem, PA, USA.
authors.forename: J D
authors.initials: JD
authors.lastname: Balshi
authors.affiliation: Department of Surgery; Department of Research and Innovation, St. Luke's University Health Network, Bethlehem, PA, USA.
authors.forename: S P
authors.initials: SP
authors.lastname: Stawicki
authors.affiliation: Department of Surgery, The Ohio State University College of Medicine, Columbus, OH, USA.
authors.forename: D C
authors.initials: DC
authors.lastname: Evans
mesh_terms: D005260:Female; D006801:Humans; D016015:Logistic Models; D035002:Lower Extremity; D008297:Male; D015999:Multivariate Analysis; D016017:Odds Ratio; D010359:Patient Readmission / Q000706:statistics & numerical data*; D058729:Peripheral Arterial Disease / Q000208:ethnology / Q000601:surgery / Q000628:therapy*; D011183:Postoperative Complications / Q000097:blood / Q000453:epidemiology / Q000209:etiology* / Q000628:therapy; D011184:Postoperative Period; D012189:Retrospective Studies; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D013514:Surgical Procedures, Operative / Q000009:adverse effects*; D013997:Time Factors; D016896:Treatment Outcome; D014656:Vascular Surgical Procedures / Q000009:adverse effects*