title: Clinical impact of lung age on postoperative readmission in non-small cell lung cancer.
abstract: BACKGROUND
  Recently, the Japanese Respiratory Society (JRS) proposed using lung age (LA) as an indicator of lung function; however, reports regarding the association of LA with the risk of postoperative readmission within 90 d after surgical treatment for non-small cell lung cancer (NSCLC) are limited. Here, we analyze the clinical relationship between LA and readmission within 90 d after surgical treatment for NSCLC.
  
  
  METHODS
  A total of 979 patients underwent curative resections for NSCLC from January 2000-September 2012 at the Kitasato University Hospital. We selected patients who required readmission because of surgical complications within 90 d of surgery and retrospectively analyzed various clinical data. LA was calculated based on the formula given by the Japanese Respiratory Society, which relies on preoperative respiratory function. We also calculated the age gap (AG) between the calculated LA and the true age (TA).
  
  
  RESULTS
  There were 216 patients who needed to be readmitted within 90 d of surgery, 33 (3%) of whom were hospitalized for surgical complications. Twenty-four patients (73%) had respiratory complications, and 7 patients (21%) died. There were significant differences between the readmitted and no readmitted patients in terms of preoperative factors, such as gender, LA, AG, smoking status, and smoking index (P < 0.05). In addition, there were significant differences in intraoperative blood loss, postoperative complications, histologic type, duration of hospitalization, and hospitalization after surgery (P < 0.05). Multivariate analysis using logistic regression indicated that LA, AG, blood loss, and postoperative complications were independent factors that predicted readmission. Additionally, the 5-y survival rates were 78% and 44% for the no readmitted and readmitted groups, respectively (P < 0.001).
  
  
  CONCLUSIONS
  The AG between TA and LA was significantly associated with postoperative complications and remained an independent predictive factor after multiple regressions. LA was shown to be a useful factor for predicting the risk of surgery-related readmission within 90 d after surgery for NSCLC.
authors.affiliation: Department of Pharmacology, Kitasato University School of Medicine, Kanagawa, Japan; Department of Clinical Research Center, Kitasato University School of Medicine, Kanagawa, Japan. Electronic address: fumihiro@med.kitasato-u.ac.jp.
authors.forename: Fumihiro
authors.initials: F
authors.lastname: Ogawa
authors.affiliation: Department of Thoracic Surgery, Kitasato University School of Medicine, Kanagawa, Japan.
authors.forename: Yukitoshi
authors.initials: Y
authors.lastname: Satoh
authors.affiliation: Department of Thoracic Surgery, Toho University School of Medicine, Tokyo, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Iyoda
authors.affiliation: Department of Pharmacology, Kitasato University School of Medicine, Kanagawa, Japan.
authors.forename: Hideki
authors.initials: H
authors.lastname: Amano
authors.affiliation: Department of Pharmacology, Kitasato University School of Medicine, Kanagawa, Japan; Department of Clinical Research Center, Kitasato University School of Medicine, Kanagawa, Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Kumagai
authors.affiliation: Department of Pharmacology, Kitasato University School of Medicine, Kanagawa, Japan.
authors.forename: Masataka
authors.initials: M
authors.lastname: Majima
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002289:Carcinoma, Non-Small-Cell Lung / Q000401:mortality / Q000601:surgery*; D015897:Comorbidity; D005260:Female; D006801:Humans; D016015:Logistic Models; D008175:Lung Neoplasms / Q000401:mortality / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D010359:Patient Readmission / Q000706:statistics & numerical data*; D011183:Postoperative Complications / Q000401:mortality; D011237:Predictive Value of Tests; D012129:Respiratory Function Tests; D012189:Retrospective Studies; D012307:Risk Factors; D015996:Survival Rate
keywords: Lung age; Non–small cell lung cancer; Postoperative complications; Readmission; Surgical resection