Isolated IgG2 deficiency is an independent risk factor for exacerbations in bronchiectasis

Yang Zhang, Andrea Clarke, K H Regan, K Campbell, Samantha Donaldson, J Crowe, A G Rossi, A T Hill

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

Background: Immunoglobulin G (IgG) subclass 2 deficiency is the most frequent IgG subclass deficiency identified in patients with bronchiectasis, but its clinical significance is not known.

Aim: To analyse if bronchiectasis patients with isolated IgG2 deficiency at risk of recurrent exacerbations and/or hospitalisation? Do patients with IgG2 deficiency have worse disease progression?

Design and methods: This is a retrospective study (2015-2020) exploring independent risk factors for recurrent exacerbations (three or more per year) and/or hospitalisation with bronchiectasis exacerbations using multivariable models using binary logistic regression. There was no patient with IgG deficiency, IgG 1, 3 or 4 deficiency, or IgA or IgM deficiency included. In this model, the authors included: serum IgG2 level; lung function; body mass index; MRC breathlessness scale; age; sex; number of bronchiectatic lobes; bacterial colonisation; comorbidities; the use of long-term immunosuppressant drugs or antibiotics for more than 28 days. Analysing two-year longitudinal data, one-way ANOVA and Mann-Whitney U test were used to compare bronchiectasis severity between patients with different IgG2 levels.

Results: Serum IgG2 levels (<2.68 g/L, 2.68-3.53 g/L, 3.54-4.45 g/L); hospital admission in the preceding two years; bacterial colonisation with potentially pathogenic organisms and asthma were independent predictors for three or more bronchiectasis exacerbations. Those with low IgG2 levels (<2.68 g/L and 2.68-3.53 g/L), had worsening progression of their bronchiectasis, using the Bronchiectasis Severity Index, over one year compared with those who were IgG2 replete (>4.45 g/L))(p = 0.003, 0.013).

Conclusion: Reduced IgG2 levels was an independent predictor for bronchiectasis exacerbations and have increased disease progression.
Original languageEnglish
Pages (from-to)292-297
JournalQJM: An International Journal of Medicine
DOIs
Publication statusPublished - 10 May 2021

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