title: Cystatin C as a Predictor of In-Hospital Mortality After Exacerbation of COPD.
abstract: BACKGROUND
  COPD is associated with cardiovascular and renal dysfunction. Cystatin C (CysC) is a biomarker of renal function and an independent risk factor for all-cause and cardiovascular mortality among elderly persons. The aim of the study was to examine the prognostic role of CysC for in-hospital mortality in subjects with a COPD exacerbation.
  
  
  METHODS
  Upon admission, serum CysC levels and arterial blood gas analysis from 477 subjects with a COPD exacerbation were measured. Clinical characteristics were also recorded. A receiver operating characteristic curve analysis was used to determine the level of CysC that discriminated survivors from non-survivors. Univariate and multiple logistic regression analyses were used to identify the risk factors for in-hospital mortality. To reduce the influence of confounders, subgroup analyses were performed according to the comorbidities, including states of heart failure, renal dysfunction, and pH, PaCO2 , and PaO2 levels.
  
  
  RESULTS
  During the in-hospital period, 59 subjects died, and 418 subjects recovered. The decedent group showed lower pH (7.27 ± 0.17 vs 7.38 ± 0.06, P < .001), higher CysC (2.21 ± 1.05 mg/L vs 1.39 ± 0.54 mg/L, P < .001), higher PaCO2 (77 ± 39 mm Hg vs 48 ± 14 mm Hg, P < .001), and lower PaO2 (74 ± 32 mm Hg vs 84 ± 26 mm Hg, P < .001) levels. The area under the receiver operating characteristic curve for the CysC prediction of death was 0.77 (95% CI 0.70-0.84). CysC values ≥1.59 mg/L were associated with significantly higher in-hospital mortality (relative risk = 5.49, 95% CI 3.24-9.32, P < .001). Multiple logistic regression analysis showed that pH <7.20, CysC ≥1.59 mg/L, and heart failure were independent predictors of in-hospital mortality. The subgroup analysis showed that the comorbid states of renal dysfunction, congestive heart failure, and the levels of pH, PaCO2 , and PaO2 did not alter the conclusion that CysC was a mortality risk factor for subjects with a COPD exacerbation.
  
  
  CONCLUSIONS
  CysC was a strong and independent risk factor for hospital mortality secondary to COPD exacerbation.
authors.affiliation: Department of Respiratory Medicine, Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong, China.
authors.forename: Guoping
authors.initials: G
authors.lastname: Hu
authors.affiliation: Department of Respiratory Disease, People's Hospital of Guangxi Zhuang Autonomous Region, Guangxi Zhuang Autonomous Region, China.
authors.forename: Yankui
authors.initials: Y
authors.lastname: Wu
authors.affiliation: Guangzhou Institute of Respiratory Disease, State Key Laboratory of Respiratory Disease, First Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong, China.
authors.forename: Yumin
authors.initials: Y
authors.lastname: Zhou
authors.affiliation: Department of Respiratory Medicine, Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Yu
authors.affiliation: Department of Respiratory Medicine, Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong, China.
authors.forename: Weiqiang
authors.initials: W
authors.lastname: Liang
authors.affiliation: Guangzhou Institute of Respiratory Disease, State Key Laboratory of Respiratory Disease, First Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong, China. pxran@vip.163.com.
authors.forename: Pixin
authors.initials: P
authors.lastname: Ran
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood; D001784:Blood Gas Analysis; D015897:Comorbidity; D055316:Cystatin C / Q000097:blood*; D018450:Disease Progression; D005260:Female; D006333:Heart Failure / Q000097:blood / Q000401:mortality; D017052:Hospital Mortality; D006801:Humans; D016015:Logistic Models; D008297:Male; D015999:Multivariate Analysis; D011379:Prognosis; D029424:Pulmonary Disease, Chronic Obstructive / Q000097:blood* / Q000401:mortality*; D012372:ROC Curve; D051437:Renal Insufficiency / Q000097:blood / Q000401:mortality; D012307:Risk Factors
chemical_list: D015415:Biomarkers; C525030:CST3 protein, human; D055316:Cystatin C
keywords: COPD exacerbation; cystatin C; mortality; prognosis