Elevated risk of chronic obstructive pulmonary disease in systemic lupus erythematosus: a population-based study
© Avina-Zubieta et al.; licensee BioMed Central Ltd. 2014
Published: 18 September 2014
Chronic obstructive pulmonary disease (COPD) has been recently recognized as an inflammatory disease. A recent Swedish hospital-based study found an increased risk of COPD in patients with a number of autoimmune conditions including systemic lupus erythematosus (SLE). We wonder whether the risk is also present in SLE patients from the general population. The objective was to assess the future risk of newly recorded COPD cases among incident SLE cases compared with controls from the general population using physician billing and hospitalization data that cover the entire province of British Columbia (BC), Canada.
Our data include all health professionals and hospital visits covered by the comprehensive provincial medical services plan (1990 to 2010) and all dispensed medication (1996 to 2010), for all BC residents. We conducted a retrospective matched cohort (1996 to 2010) study among patients satisfying at least one of the following validated criteria: one diagnostic code for SLE (ICD-9-CM = 710.0) on at least two visits within a 2-year period by a nonrheumatologist physician; one ICD-9 code by a rheumatologist or from hospitalization; and absence of a prior SLE diagnosis between 1990 and 1995. Ten controls matched by birth year, sex and calendar year of exposure were randomly selected from the general population for each case. Outcome: we used a validated criteria to define COPD (first ICD-9-CM: 491, 492, 496, 493.2, or ICD-10-CM J43 or J44) from hospitals or death certificates. We estimated relative risks (RRs) by comparing SLE cases with age-matched, sex-matched and entry-time-matched comparison cohorts, adjusting for confounders. Sensitivity analyses were conducted to assess for unmeasured confounders.
Risk of incident COPD according to SLE status
SLE (n= 4,486)
Non-SLE (n= 47,190)
COPD cases, n
Incidence rate/1,000 person-years
Age-matched, sex-matched, and entry time-matched RRs (95% CI)
2.3 (1.8 to 2.9)
<1 year of disease duration
6.1 (4.0 to 9.2)
1to 4.9 years of disease duration
1.7 (1.2 to 2.5)
5+ years of disease duration
1.5 (0.9 to 2.3)
Multivariable RR (95% CI)
2.0 (1.5 to 2.6)
This is the first general population-based study indicating a twofold increased risk of COPD in patients with SLE. The risk of developing COPD was highest within the first year, declining thereafter, suggesting the potential pathogenic role of inflammation in the development of COPD.
Research funded by an operating grant from the Canadian Arthritis Network/The Arthritis Society and the BC Lupus Society (Grant 10-SRP-IJD-01).
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