title: Increased risk of pneumonia among patients with inflammatory bowel disease.
abstract: OBJECTIVE
  Patients with inflammatory bowel disease (IBD) may be at increased risk for infections. We aimed to determine the pneumonia risk in IBD and how specific medications affect this risk.
  
  
  METHODS
  We performed a retrospective cohort and a nested case-control study using administrative data from IMS Health Inc., LifeLink Health Plan Claims Database. Limitations to this data set include lack of clinical details to validate exposures and outcomes. In the cohort, IBD patients were matched to four individuals without IBD. Pneumonia risk was evaluated by incidence rate ratio (IRR) and adjusted Cox proportional hazards models (hazard ratio (HR)). In the nested case-control, 4,856 IBD patients with pneumonia were matched to four IBD patients without pneumonia by incidence density sampling. We used conditional logistic regression to determine the associations between medications and pneumonia.
  
  
  RESULTS
  The cohort included 50,932 patients with Crohn's disease (CD), 56,403 patients with ulcerative colitis (UC), and 1,269 with unspecified IBD; matched to 434,416 individuals without IBD. Median follow-up within the cohort was 24 months. The IBD cohort had an increased pneumonia risk when compared with non-IBD (IRR 1.82, 95% confidence interval (CI) 1.75-1.88). In adjusted Cox analysis, pneumonia risk remained increased for the IBD vs. non-IBD cohort (HR 1.54, 95% CI 1.49-1.60), with increased risk in both CD (HR 1.71, 95% CI 1.62-1.80) and UC (HR 1.41, 95% CI 1.34-1.48). In the nested case-control analysis, use of biologic medications (odds ratio (OR) 1.32, 95% CI 1.11-1.57), corticosteroids (OR 1.91, 95% CI 1.72-2.12), thiopurines (OR 1.13, 95% CI 1.00-1.27), proton-pump inhibitors (PPIs) (OR 1.15, 95% CI 1.04-1.26), or narcotics (2.28, 95% CI 2.09-2.48) was independently associated with pneumonia.
  
  
  CONCLUSIONS
  Patients with IBD are at increased risk for pneumonia. Medications such as corticosteroids and narcotics are particularly associated with pneumonia in this population. An emphasis upon primary prevention of pneumonia through vaccination and reduction of risk factors is warranted.
authors.affiliation: Division of Gastroenterology and Hepatology, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7080, USA. millie_long@med.unc.edu
authors.forename: Millie D
authors.initials: MD
authors.lastname: Long
authors.forename: Christopher
authors.initials: C
authors.lastname: Martin
authors.forename: Robert S
authors.initials: RS
authors.lastname: Sandler
authors.forename: Michael D
authors.initials: MD
authors.lastname: Kappelman
mesh_terms: D000305:Adrenal Cortex Hormones / Q000008:administration & dosage / Q000009:adverse effects; D000328:Adult; D000368:Aged; D000893:Anti-Inflammatory Agents / Q000008:administration & dosage; D001688:Biological Products / Q000008:administration & dosage / Q000009:adverse effects; D016022:Case-Control Studies; D015331:Cohort Studies; D003093:Colitis, Ulcerative / Q000150:complications; D003424:Crohn Disease / Q000150:complications; D005260:Female; D005765:Gastrointestinal Agents / Q000008:administration & dosage* / Q000009:adverse effects*; D006801:Humans; D007166:Immunosuppressive Agents / Q000008:administration & dosage / Q000009:adverse effects; D015212:Inflammatory Bowel Diseases / Q000150:complications* / Q000188:drug therapy / Q000453:epidemiology*; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009294:Narcotics / Q000008:administration & dosage* / Q000009:adverse effects*; D016017:Odds Ratio; D018579:Patient Selection; D011014:Pneumonia / Q000139:chemically induced / Q000453:epidemiology* / Q000209:etiology* / Q000517:prevention & control; D011322:Primary Prevention / Q000379:methods; D016016:Proportional Hazards Models; D054328:Proton Pump Inhibitors / Q000008:administration & dosage / Q000009:adverse effects; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors
chemical_list: D000305:Adrenal Cortex Hormones; D000893:Anti-Inflammatory Agents; D001688:Biological Products; D005765:Gastrointestinal Agents; D007166:Immunosuppressive Agents; D009294:Narcotics; D054328:Proton Pump Inhibitors; D014409:Tumor Necrosis Factor-alpha