Lower serum IgA is associated with COPD exacerbation risk in SPIROMICS.

Publication Title

PLoS One

Authors

Nirupama Putcha
Gabriel G Paul
Antoine Azar
Robert A Wise
Wanda K O'Neal
Mark T Dransfield
Prescott G Woodruff
Jeffrey L Curtis
Alejandro P Comellas
M Bradley Drummond
Allison A. Lambert, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America; University of Washington School of Medicine, Seattle, Washington, United States of AmericaFollow
Laura M Paulin
Ashraf Fawzy
Richard E Kanner
Robert Paine
MeiLan K Han
Fernando J Martinez
Russell P Bowler
R Graham Barr
Nadia N Hansel

Document Type

Article

Publication Date

1-1-2018

Keywords

Adult; Aged; Aged, 80 and over; Biomarkers; Cohort Studies; Disease Progression; Female; Humans; Immunoglobulin A; Incidence; Male; Middle Aged; Pulmonary Disease, Chronic Obstructive; Regression Analysis; Risk; Treatment Outcome

Abstract

BACKGROUND: Decreased but measurable serum IgA levels (≤70 mg/dL) have been associated with risk for infections in some populations, but are unstudied in COPD. This study tested the hypothesis that subnormal serum IgA levels would be associated with exacerbation risk in COPD.

METHODS: Data were analyzed from 1,049 COPD participants from the observational cohort study SPIROMICS (535 (51%) women; mean age 66.1 (SD 7.8), 338 (32%) current smokers) who had baseline serum IgA measured using the Myriad RBM biomarker discovery platform. Exacerbation data was collected prospectively (mean 944.3 (SD 281.3) days), and adjusted linear, logistic and zero-inflated negative binomial regressions were performed.

RESULTS: Mean IgA was 269.1 mg/dL (SD 150.9). One individual had deficient levels of serum IgA (/dL) and 25 (2.4%) had IgA level ≤70 mg/dL. Participants with IgA ≤70 mg/dL were younger (62 vs. 66 years, p = 0.01) but otherwise similar to those with higher IgA. In adjusted models, IgA ≤70 mg/dL was associated with higher exacerbation incidence rates (IRR 1.71, 95% CI 1.01-2.87, p = 0.044) and greater risk for any severe exacerbation (OR 2.99, 95% CI 1.30-6.94, p = 0.010). In adjusted models among those in the lowest decile (/dL), each 10 mg/dL decrement in IgA (analyzed continuously) was associated with more exacerbations during follow-up (β 0.24, 95% CI 0.017-0.46, p = 0.035).

CONCLUSIONS: Subnormal serum IgA levels were associated with increased risk for acute exacerbations, supporting mildly impaired IgA levels as a contributing factor in COPD morbidity. Additionally, a dose-response relationship between lower serum IgA and number of exacerbations was found among individuals with serum IgA in the lowest decile, further supporting the link between serum IgA and exacerbation risk. Future COPD studies should more comprehensively characterize immune status to define the clinical relevance of these findings and their potential for therapeutic correction.

Specialty/Research Institute

Pulmonary Medicine

Comments

Allison Lambert is affiliated with Providence St. Joseph Health.