title: Risks of in-hospital death and complications after fusion surgery in patients with atlantoaxial subluxation: analysis of 1090 patients using the Japanese Diagnosis Procedure Combination database.
abstract: OBJECTIVE
  To examine in-hospital mortality and postoperative major complications in patients undergoing fusion surgery for atlantoaxial subluxation (AAS) and to examine whether the risk of perioperative complications varies between patients with and without rheumatoid arthritis (RA).
  
  
  METHODS
  A retrospective analysis of data from the Diagnosis Procedure Combination database, a nationwide administrative impatient database in Japan, identified 1090 patients who underwent spinal fusion surgery for AAS during 2007-2012. Patients' clinical characteristics were extracted, including age, sex, use of homologous blood transfusion, length of stay, and type of hospital. Clinical outcomes included in-hospital death and major complications, including surgical-site infection, sepsis, cardiac events, respiratory disorders, acute renal failure, pulmonary embolism, perioperative stroke, and vertebral injury. Massive blood transfusion was defined as at least 6 units of red blood cells.
  
  
  RESULTS
  Four hundred sixty-five patients (42.7%) were classified as the RA group. In-hospital mortality after fusion surgery for AAS was 0.5% (5/1090), and major complications occurred in 5% (55/1090). Multivariate analyses showed that patients with RA were more likely to have major complications after surgery than patients without RA (odds ratio: 1.69; 95% confidence interval: 0.96-2.97; P = 0.07), and the rate of massive blood transfusion was significantly greater in patients with RA than in patients without RA (odds ratio: 2.29; 95% confidence interval: 1.12-4.68; P = 0.02).
  
  
  CONCLUSIONS
  The in-hospital mortality after fusion surgery for AAS was relatively low. However, patients with RA had an increased risk of postoperative complications and massive blood transfusion compared with patients without RA.
authors.affiliation: Department of Orthopaedic Surgery, Faculty of Medicine, The University of Tokyo, Tokyo, Japan. Electronic address: oyaj-ort@h.u-tokyo.ac.jp.
authors.forename: Junichi
authors.initials: J
authors.lastname: Ohya
authors.affiliation: Department of Orthopaedic Surgery, Faculty of Medicine, The University of Tokyo, Tokyo, Japan.
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Chikuda
authors.affiliation: Department of Orthopaedic Surgery, Faculty of Medicine, The University of Tokyo, Tokyo, Japan.
authors.forename: So
authors.initials: S
authors.lastname: Kato
authors.affiliation: Department of Clinical Epidemiology and Health Economics, School of Public Health, The University of Tokyo, Tokyo, Japan.
authors.forename: Hiromasa
authors.initials: H
authors.lastname: Horiguchi
authors.affiliation: Department of Orthopaedic Surgery, Faculty of Medicine, The University of Tokyo, Tokyo, Japan.
authors.forename: Katsushi
authors.initials: K
authors.lastname: Takeshita
authors.affiliation: Department of Orthopaedic Surgery, Faculty of Medicine, The University of Tokyo, Tokyo, Japan.
authors.forename: Sakae
authors.initials: S
authors.lastname: Tanaka
authors.affiliation: Department of Clinical Epidemiology and Health Economics, School of Public Health, The University of Tokyo, Tokyo, Japan.
authors.forename: Hideo
authors.initials: H
authors.lastname: Yasunaga
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001268:Atlanto-Axial Joint / Q000293:injuries*; D016208:Databases, Factual; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000401:mortality*; D012306:Risk; D013123:Spinal Fusion / Q000401:mortality*; D016896:Treatment Outcome
keywords: Atlantoaxial subluxation; Complications; Database; Mortality; Rheumatoid arthritis