title: Rheumatoid arthritis lung disease. Determinants of radiographic and physiologic abnormalities.
abstract: OBJECTIVE
  To determine the prevalence and important clinical predictors of radiographic and physiologic abnormalities indicative of rheumatoid arthritis interstitial lung disease (RA-ILD).
  
  
  METHODS
  An unselected cohort of patients with a confirmed diagnosis of RA and known lung disease were identified (n = 336) and evaluated for RA disease activity and severity. Outcomes included abnormalities determined by the pulmonary function tests of forced vital capacity (FVC) and diffusion capacity for carbon monoxide (DLco), and/or chest radiographic findings of interstitial infiltrates. We used multivariable statistical modeling to determine the independent significance of cigarette smoking and other RA-specific factors on the pulmonary abnormalities of interest.
  
  
  RESULTS
  At least 1 of the 3 abnormal findings was identified by pulmonary tests in 32.4% of all patients. These abnormal findings included an FVC < 80% of predicted in 42 patients, a DLco < 80% of predicted in 64 patients, and evidence of radiographic interstitial infiltrates in 40 patients. After statistical adjustment for confounding factors, pack-years of cigarette smoking remained a significant predictor of low DLco (beta = -0.07, 95% confidence interval [95% CI] -0.09, -0.04), low FVC (beta = -0.003, 95% CI -0.006, -0.0004), and interstitial abnormalities on chest radiograph (odds ratio for > or = 25 pack-years = 3.76, 95% CI 1.59, 8.88). The Health Assessment Questionnaire (HAQ) Disability Index (DI) was also an important risk factor for the decline in both the DLco (beta = -1.15, 95% CI -2.00, -0.30) and FVC (beta = -0.23, 95% CI -0.32, -0.13).
  
  
  CONCLUSIONS
  Although RA disease activity/severity (particularly as defined by the HAQ DI) was important, smoking was the most consistent independent predictor of radiographic and physiologic abnormalities suggestive of ILD in RA.
authors.affiliation: Department of Internal Medicine, University of Iowa College of Medicine, Iowa City 52242, USA.
authors.forename: K G
authors.initials: KG
authors.lastname: Saag
authors.forename: S
authors.initials: S
authors.lastname: Kolluri
authors.forename: R K
authors.initials: RK
authors.lastname: Koehnke
authors.forename: T A
authors.initials: TA
authors.lastname: Georgou
authors.forename: J W
authors.initials: JW
authors.lastname: Rachow
authors.forename: G W
authors.initials: GW
authors.lastname: Hunninghake
authors.forename: D A
authors.initials: DA
authors.lastname: Schwartz
mesh_terms: D000328:Adult; D018501:Antirheumatic Agents / Q000494:pharmacology; D001172:Arthritis, Rheumatoid / Q000000981:diagnostic imaging* / Q000188:drug therapy* / Q000453:epidemiology; D015331:Cohort Studies; D005260:Female; D006046:Gold / Q000494:pharmacology; D006801:Humans; D017563:Lung Diseases, Interstitial / Q000000981:diagnostic imaging* / Q000453:epidemiology / Q000503:physiopathology*; D008297:Male; D008727:Methotrexate / Q000494:pharmacology; D008875:Middle Aged; D015999:Multivariate Analysis; D010396:Penicillamine / Q000494:pharmacology; D015995:Prevalence; D011859:Radiography; D012129:Respiratory Function Tests; D012907:Smoking / Q000009:adverse effects
chemical_list: D018501:Antirheumatic Agents; D006046:Gold; D010396:Penicillamine; D008727:Methotrexate