title: Superiority of respiratory failure risk index in prediction of postoperative pulmonary complications after digestive surgery in Japanese patients.
abstract: BACKGROUND
  Several multifactorial risk indexes have been proposed by Western countries for identifying patients at a high risk of developing postoperative pulmonary complications (PPC). However, there is no consensus on how to evaluate the risk of PPC and what multifactorial risk index should be adapted for Japanese patients. This study aimed at clarifying the utility of risk indexes to predict PPC following digestive surgeries in Japanese patients.
  
  
  METHODS
  We retrospectively analyzed 892 patients who underwent digestive surgeries under general anesthesia in Niigata University Medical and Dental Hospital between January 2009 and March 2011. PPC was defined as postoperative respiratory failure and postoperative pneumonia. We calculated three risk indexes (respiratory failure risk index (RFRI), postoperative pneumonia risk index, and PPC risk score), and compared them between the PPC group and the non-PPC group. A receiver operating characteristic (ROC) curve analysis was employed to compare the usefulness of each index.
  
  
  RESULTS
  PPC developed in 55 patients (6.2%). All risk indexes were significantly higher in the PPC group than the non-PPC group. The category classification of the risk scores demonstrated a significant tendency to increase the incidence rate of PPC. In the ROC analysis, the area under the curve for RFRI was 0.762 (95% CI 0.697-0.826), which was the highest value observed among these indexes.
  
  
  CONCLUSIONS
  Multifactorial risk indexes are useful tools for identifying Japanese patients at a high risk of developing PPC following digestive surgeries. Of the risk indexes evaluated in this study, RFRI is potentially the most accurate in predicting PPC.
authors.affiliation: Division of Respiratory Medicine, Graduate School of Medical and Dental Sciences, Niigata University, 1-757 Asahimachidori, Chuo-ku, Niigata-shi, Niigata 951-8510, Japan. Electronic address: g1jockey@nifty.com.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Hokari
authors.affiliation: Division of Respiratory Medicine, Graduate School of Medical and Dental Sciences, Niigata University, 1-757 Asahimachidori, Chuo-ku, Niigata-shi, Niigata 951-8510, Japan. Electronic address: ohshima@med.niigata-u.ac.jp.
authors.forename: Yasuyoshi
authors.initials: Y
authors.lastname: Ohshima
authors.affiliation: Department of Respiratory Medicine, Tokyo Medical University, 6-7-1 Nishishinjuku, Shinjuku-ku, Tokyo 160-0023, Japan. Electronic address: hidenaka@tokyo-med.ac.jp.
authors.forename: Hideaki
authors.initials: H
authors.lastname: Nakayama
authors.affiliation: Division of Respiratory Medicine, Graduate School of Medical and Dental Sciences, Niigata University, 1-757 Asahimachidori, Chuo-ku, Niigata-shi, Niigata 951-8510, Japan. Electronic address: cockcock77jp@yahoo.co.jp.
authors.forename: Ryoko
authors.initials: R
authors.lastname: Suzuki
authors.affiliation: Division of Respiratory Medicine, Graduate School of Medical and Dental Sciences, Niigata University, 1-757 Asahimachidori, Chuo-ku, Niigata-shi, Niigata 951-8510, Japan. Electronic address: alcyone7sebi@yahoo.co.jp.
authors.forename: Tomosue
authors.initials: T
authors.lastname: Kajiwara
authors.affiliation: Division of Respiratory Medicine, Graduate School of Medical and Dental Sciences, Niigata University, 1-757 Asahimachidori, Chuo-ku, Niigata-shi, Niigata 951-8510, Japan. Electronic address: tkoya@med.niigata-u.ac.jp.
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Koya
authors.affiliation: Division of Respiratory Medicine, Graduate School of Medical and Dental Sciences, Niigata University, 1-757 Asahimachidori, Chuo-ku, Niigata-shi, Niigata 951-8510, Japan. Electronic address: hkagamu@med.niigata-u.ac.jp.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kagamu
authors.affiliation: Division of Respiratory Medicine, Graduate School of Medical and Dental Sciences, Niigata University, 1-757 Asahimachidori, Chuo-ku, Niigata-shi, Niigata 951-8510, Japan; Uonuma Institute of Community Medicine, Niigata University Medical and Dental Hospital, 1-754 Asahimachidori, Chuo-ku, Niigata-shi, Niigata 951-8510, Japan. Electronic address: ttakada@med.niigata-u.ac.jp.
authors.forename: Toshinori
authors.initials: T
authors.lastname: Takada
authors.affiliation: Niigata University Medical and Dental Hospital, 1-754 Asahimachidori, Chuo-ku, Niigata-shi, Niigata 951-8510, Japan. Electronic address: eiichi@med.niigata-u.ac.jp.
authors.forename: Eiichi
authors.initials: E
authors.lastname: Suzuki
authors.affiliation: Division of Respiratory Medicine, Graduate School of Medical and Dental Sciences, Niigata University, 1-757 Asahimachidori, Chuo-ku, Niigata-shi, Niigata 951-8510, Japan. Electronic address: naritai@med.niigata-u.ac.jp.
authors.forename: Ichiei
authors.initials: I
authors.lastname: Narita
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D044466:Asian People; D013505:Digestive System Surgical Procedures; D005260:Female; D005544:Forecasting; D006801:Humans; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000517:prevention & control*; D012131:Respiratory Insufficiency / Q000517:prevention & control*; D012189:Retrospective Studies; D012306:Risk; D018570:Risk Assessment / Q000379:methods*; D055815:Young Adult
keywords: Postoperative complication; Postoperative pneumonia; Respiratory failure; Risk index