title: Preoperative pulmonary risk stratification for noncardiothoracic surgery: systematic review for the American College of Physicians.
abstract: BACKGROUND
  The importance of clinical risk factors for postoperative pulmonary complications and the value of preoperative testing to stratify risk are the subject of debate.
  
  
  OBJECTIVE
  To systematically review the literature on preoperative pulmonary risk stratification before noncardiothoracic surgery.
  
  
  METHODS
  MEDLINE search from 1 January 1980 through 30 June 2005 and hand search of the bibliographies of retrieved articles.
  
  
  METHODS
  English-language studies that reported the effect of patient- and procedure-related risk factors and laboratory predictors on postoperative pulmonary complication rates after noncardiothoracic surgery and that met predefined inclusion criteria.
  
  
  METHODS
  The authors used standardized abstraction instruments to extract data on study characteristics, hierarchy of research design, study quality, risk factors, and laboratory predictors.
  
  
  RESULTS
  The authors determined random-effects pooled estimate odds ratios and, when appropriate, trim-and-fill estimates for patient- and procedure-related risk factors from studies that used multivariable analyses. They assigned summary strength of evidence scores for each factor. Good evidence supports patient-related risk factors for postoperative pulmonary complications, including advanced age, American Society of Anesthesiologists class 2 or higher, functional dependence, chronic obstructive pulmonary disease, and congestive heart failure. Good evidence supports procedure-related risk factors for postoperative pulmonary complications, including aortic aneurysm repair, nonresective thoracic surgery, abdominal surgery, neurosurgery, emergency surgery, general anesthesia, head and neck surgery, vascular surgery, and prolonged surgery. Among laboratory predictors, good evidence exists only for serum albumin level less than 30 g/L. Insufficient evidence supports preoperative spirometry as a tool to stratify risk.
  
  
  CONCLUSIONS
  For certain risk factors and laboratory predictors, the literature provides only unadjusted estimates of risk. Prescreening, variable selection algorithms, and publication bias limited reporting of risk factors among studies using multivariable analysis.
  
  
  CONCLUSIONS
  Selected clinical and laboratory factors allow risk stratification for postoperative pulmonary complications after noncardiothoracic surgery.
authors.affiliation: Division of General Medicine and Primary Care, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215, USA. gsmetana@bidmc.harvard.edu
authors.forename: Gerald W
authors.initials: GW
authors.lastname: Smetana
authors.forename: Valerie A
authors.initials: VA
authors.lastname: Lawrence
authors.forename: John E
authors.initials: JE
authors.lastname: Cornell
mesh_terms: D019411:Clinical Laboratory Techniques; D006801:Humans; D008171:Lung Diseases / Q000209:etiology / Q000517:prevention & control*; D011183:Postoperative Complications / Q000517:prevention & control*; D012131:Respiratory Insufficiency / Q000209:etiology / Q000517:prevention & control*; D018570:Risk Assessment; D012307:Risk Factors; D013514:Surgical Procedures, Operative