title: Risk of mycobacterial infections associated with rheumatoid arthritis in Ontario, Canada.
abstract: OBJECTIVE
  Patients with rheumatoid arthritis (RA) are at increased risk of TB. Little is known about the risk of nontuberculous mycobacteria (NTM) disease in these patients. We sought to ascertain the rate of NTM infection and TB in all residents of Ontario, Canada, with and without RA.
  
  
  METHODS
  In a cohort study, all Ontarians aged ≥ 15 years in January 2001 were followed until December 2010. Individuals with RA were identified using a validated algorithm to search hospitalization and physician billing claims. We linked Public Health Ontario Laboratory data to identify all cases of laboratory-confirmed TB and NTM disease. Analysis was performed using Cox proportional hazards regression.
  
  
  RESULTS
  We identified 113,558 Ontarians with RA and 9,760,075 Ontarians without RA. Relative to the non-RA group, adjusted hazard ratios (HRs) and 95% CIs for TB (1.92, [1.50-2.47]) and NTM disease (2.07, [1.84-2.32]) demonstrated increased risks in the RA group. Among those with RA, per 100,000 person-years, NTM disease (HR, 41.6; 95% CI, 37.1-46.5) was more common than TB (HR, 8.5; 95% CI, 6.5-10.8). After full adjustment, people with RA who developed NTM disease were 1.81 times as likely to die than uninfected people with RA.
  
  
  CONCLUSIONS
  Mycobacterial infections are more common in Ontarians with RA, with NTM disease more likely than TB. NTM disease is associated with an increased risk of death in patients with RA. Given the rising rates of NTM disease worldwide, determining whether this risk is due to the use of immunosuppressive medications vs RA itself is an important objective for future research.
authors.affiliation: Joint Division of Respirology, University Health Network, Mount Sinai Hospital, Toronto; Westpark Healthcare Centre, Toronto; Department of Medicine, Management and Evaluation, University of Toronto, Toronto.
authors.forename: Sarah K
authors.initials: SK
authors.lastname: Brode
authors.affiliation: Department of Laboratory Medicine and Pathobiology, Management and Evaluation, University of Toronto, Toronto; Public Health Ontario, Toronto.
authors.forename: Frances B
authors.initials: FB
authors.lastname: Jamieson
authors.affiliation: Department of Medicine, Management and Evaluation, University of Toronto, Toronto.
authors.forename: Ryan
authors.initials: R
authors.lastname: Ng
authors.affiliation: Institute for Clinical Evaluative Sciences, Toronto.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Campitelli
authors.affiliation: Department of Medicine and Toronto Western Family Health Team, University Health Network, Mount Sinai Hospital, Toronto; Department of Family and Community Medicine, Management and Evaluation, University of Toronto, Toronto; Public Health Ontario, Toronto; Institute for Clinical Evaluative Sciences, Toronto.
authors.forename: Jeffrey C
authors.initials: JC
authors.lastname: Kwong
authors.affiliation: Institute of Health Policy, Management and Evaluation, University of Toronto, Toronto; Institute for Clinical Evaluative Sciences, Toronto; Department of Family Medicine, McMaster University, Hamilton.
authors.forename: J Michael
authors.initials: JM
authors.lastname: Paterson
authors.affiliation: Institute for Clinical Evaluative Sciences, Toronto.
authors.forename: Ping
authors.initials: P
authors.lastname: Li
authors.affiliation: Public Health Ontario, Toronto.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Marchand-Austin
authors.affiliation: Institute of Health Policy, Management and Evaluation, University of Toronto, Toronto; Toronto General Hospital Research Institute, Toronto, ON, Canada.
authors.forename: Claire
authors.initials: C
authors.lastname: Bombardier
authors.affiliation: Joint Division of Respirology, University Health Network, Mount Sinai Hospital, Toronto; Department of Medicine, Management and Evaluation, University of Toronto, Toronto. Electronic address: ted.marras@uhn.ca.
authors.forename: Theodore K
authors.initials: TK
authors.lastname: Marras
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001172:Arthritis, Rheumatoid / Q000150:complications* / Q000453:epidemiology; D015331:Cohort Studies; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009164:Mycobacterium Infections / Q000453:epidemiology*; D009165:Mycobacterium Infections, Nontuberculous / Q000453:epidemiology*; D009864:Ontario / Q000453:epidemiology; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D012307:Risk Factors; D055815:Young Adult