title: Are risk predicting models useful for estimating survival of patients with rheumatoid arthritis-associated interstitial lung disease?
abstract: Risk predicting models have been applied in idiopathic pulmonary fibrosis (IPF), but still not validated in patients with rheumatoid arthritis-associated interstitial lung disease (RA-ILD). The purpose of this study was to test the suitability of three prediction models as well as individual lung function and demographic factors for evaluating the prognosis of RA-ILD patients.
  
  
  
  Clinical and radiological data of 59 RA-ILD patients was re-assessed. GAP (gender, age, physiologic variables) and the modified interstitial lung disease (ILD)-GAP as well as the composite physiologic indexes (CPI) were tested for predicting mortality using the goodness-of-fit test and Cox model. Potential predictors of mortality were also sought from single lung function parameters and clinical characteristics.
  
  
  
  The median survival was 152 and 61 months in GAP / ILD-GAP stages I and II (p = 0.017). Both GAP and ILD-GAP models accurately estimated 1-year, 2-year and 3-year mortality. CPI (p = 0.025), GAP (p = 0.008) and ILD-GAP (p = 0.028) scores, age (p = 0.002), baseline diffusion capacity to carbon monoxide (DLCO) (p = 0.014) and hospitalization due to respiratory reasons (p = 0.039), were significant predictors of mortality in the univariate analysis, whereas forced vital capacity (FVC) was not predictive. CPI score (HR 1.03, p = 0.018) and baseline DLCO (HR 0.97, p = 0.011) remained significant predictors of mortality after adjusting for age.
  
  
  
  GAP and ILD-GAP are applicable for evaluating the risk of death of patients with RA-ILD in a similar manner as in those with IPF. Baseline DLCO and CPI score also predicted survival.
authors.affiliation: Center of Medicine and Clinical Research, Division of Respiratory Medicine, Kuopio University Hospital, POB 100, 70029, Kuopio, Finland. hanna.nurmi@kuh.fi.|Division of Respiratory Medicine, Institute of Clinical Medicine, School of Medicine, Faculty of Health Sciences, University of Eastern Finland, POB 1627, 70211, Kuopio, Finland. hanna.nurmi@kuh.fi.
authors.forename: Hanna M
authors.initials: HM
authors.lastname: Nurmi
authors.affiliation: Center of Medicine and Clinical Research, Division of Respiratory Medicine, Kuopio University Hospital, POB 100, 70029, Kuopio, Finland.
authors.forename: Minna K
authors.initials: MK
authors.lastname: Purokivi
authors.affiliation: Division of Respiratory Medicine, Institute of Clinical Medicine, School of Medicine, Faculty of Health Sciences, University of Eastern Finland, POB 1627, 70211, Kuopio, Finland.
authors.forename: Miia S
authors.initials: MS
authors.lastname: Kärkkäinen
authors.affiliation: Diagnostic Imaging Center, Division of Radiology, Kuopio University Hospital, POB 100, 70029, Kuopio, Finland.
authors.forename: Hannu-Pekka
authors.initials: HP
authors.lastname: Kettunen
authors.affiliation: Science Services Center, Kuopio University Hospital, POB 100, 70029, Kuopio, Finland.
authors.forename: Tuomas A
authors.initials: TA
authors.lastname: Selander
authors.affiliation: Center of Medicine and Clinical Research, Division of Respiratory Medicine, Kuopio University Hospital, POB 100, 70029, Kuopio, Finland.|Division of Respiratory Medicine, Institute of Clinical Medicine, School of Medicine, Faculty of Health Sciences, University of Eastern Finland, POB 1627, 70211, Kuopio, Finland.|Respiratory Medicine, Internal Medicine Research Unit, Medical Research Center Oulu, Oulu University Hospital and University of Oulu, POB 20, 90029, Oulu, Finland.
authors.forename: Riitta L
authors.initials: RL
authors.lastname: Kaarteenaho
mesh_terms: D000367:Age Factors; D000368:Aged; D001172:Arthritis, Rheumatoid / Q000150:complications*; D015331:Cohort Studies; D005260:Female; D005387:Finland / Q000453:epidemiology; D006801:Humans; D017563:Lung Diseases, Interstitial / Q000175:diagnosis* / Q000401:mortality*; D008297:Male; D008875:Middle Aged; D008962:Models, Theoretical; D011379:Prognosis; D016016:Proportional Hazards Models; D012720:Severity of Illness Index; D015996:Survival Rate; D014057:Tomography, X-Ray Computed; D014797:Vital Capacity
keywords: Composite physiologic index; GAP; ILD-GAP; Interstitial lung disease; Mortality; RA-ILD; Rheumatoid arthritis