title: The Value of Biomarkers as Predictors of Outcome in Patients with Rheumatoid Arthritis-Associated Usual Interstitial Pneumonia.
abstract: BACKGROUND
  Because of the highly variable clinical course of rheumatoid arthritis-associated usual interstitial pneumonia (RA-UIP), the prediction of patient prognosis is important.
  
  
  OBJECTIVE
  The aim of this study was to investigate the role of blood biomarkers as prognostic predictors in the patients with RA-UIP.
  
  
  METHODS
  The blood levels of biomarkers (Krebs von den Lungen-6 [KL-6], surfactant protein-A [SP-A], matrix metalloproteinase-7 [MMP-7], interleukin-6 [IL-6], and interleukin-32 [IL-32]) were retrospectively compared with the clinical courses of 62 patients with RA-UIP.
  
  
  RESULTS
  The median follow-up period was 33.4 months. RA-UIP progressed in 15 patients (45.2%) during one year of follow-up. We found that KL-6 and IL-6 were significant predictors of short-term (1 year) prognosis. Multivariate logistic regression analysis showed that the odds ratio (OR) for KL-6 was 1.001 (95% confidence interval [CI]: 1.000-1.003, p = 0.077) and that the OR for IL-6 was 1.040 (95% CI: 1.002-1.080, p = 0.039) for short-term disease progression. The addition of KL-6 and IL-6 to the clinical parameters (concordance index [C-index]: 0.958, p = 0.053) predicted short-term disease progression better than the clinical parameter alone (C-index: 0.853). In addition, patients with high levels of KL-6 (≥933 U/mL) had shorter survival than those with low levels of KL-6 (<933 U/mL) (median survival: 51 vs. 96 months, p = 0.019).
  
  
  CONCLUSIONS
  The results of this retrospective study suggested that KL-6 and IL-6 could be used as predictors of short-term disease progression. In addition, high levels of KL-6 could be used as a predictor of mortality. Additional studies involving a larger patient cohort are warranted.
authors.affiliation: Division of Respiratory and Critical Care Medicine, Department of Internal Medicine, Korea University Medical Center, Guro Hospital, Seoul. avonlea76@hanmail.net.
authors.forename: Young Seok
authors.initials: YS
authors.lastname: Lee
authors.forename: Ho Cheol
authors.initials: HC
authors.lastname: Kim
authors.forename: Bo Young
authors.initials: BY
authors.lastname: Lee
authors.forename: Chang Keun
authors.initials: CK
authors.lastname: Lee
authors.forename: Mi-Young
authors.initials: MY
authors.lastname: Kim
authors.forename: Se Jin
authors.initials: SJ
authors.lastname: Jang
authors.forename: Hye Sun
authors.initials: HS
authors.lastname: Lee
authors.forename: Jieun
authors.initials: J
authors.lastname: Moon
authors.forename: Thomas V
authors.initials: TV
authors.lastname: Colby
authors.forename: Dong Soon
authors.initials: DS
authors.lastname: Kim
mesh_terms: D000368:Aged; D001172:Arthritis, Rheumatoid / Q000150:complications* / Q000175:diagnosis / Q000401:mortality; D015415:Biomarkers / Q000097:blood; D018450:Disease Progression; D005260:Female; D006801:Humans; D015850:Interleukin-6 / Q000097:blood*; D053208:Kaplan-Meier Estimate; D016015:Logistic Models; D017563:Lung Diseases, Interstitial / Q000097:blood / Q000175:diagnosis* / Q000209:etiology / Q000401:mortality; D008297:Male; D008875:Middle Aged; D018396:Mucin-1 / Q000097:blood*; D015999:Multivariate Analysis; D016017:Odds Ratio; D011237:Predictive Value of Tests; D011379:Prognosis; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D012307:Risk Factors; D013997:Time Factors; D015854:Up-Regulation
chemical_list: D015415:Biomarkers; C508600:IL6 protein, human; D015850:Interleukin-6; C060192:MUC1 protein, human; D018396:Mucin-1
keywords: Biomarkers, Rheumatoid arthritis, Interstitial lung disease, Prognosis, KL-6, IL-6