Elevated HbA1c Tied to Increased Risk of Asthma-related Hospitalisations

Takeaway

• This study suggests that an elevated glycated haemoglobin A1c (HbA1c) is associated with an increased risk of asthma-related hospitalisations and lower forced expiratory volume in the first second (FEV₁) and forced vital capacity (FVC) among British adults with asthma but no diagnosis of diabetes mellitus.

Why this matters

• Elevated HbA1c level should be closely monitored because of a potential increased risk of asthma-related hospitalisations in patients with asthma but no diagnosis of diabetes mellitus.

Study design

• A cross-sectional study of 47,606 patients with asthma but no diagnosis of diabetes mellitus (age range, 40-69 years), who participated in the UK Biobank.
• HbA1c level was considered as both a continuous variable and a categorical variable (defined as normal [<42 mmol/mol, corresponding to a HbA1c <6%]; n=43,786) vs consistent with pre-diabetes/diabetes (≥42 mmol/mol, corresponding to a HbA1c ≥6%; n=2199).
• Funding: None disclosed.

Key results

• Of 47,606 patients, 1621 had asthma and ≥1 asthma-related hospitalisation and 45,985 had asthma but were never hospitalised.
• Each mmol/mol increment in HbA1c (OR, 1.03; 95% CI, 1.01-1.04) and a HbA1c in the pre-diabetic or diabetic range (OR, 1.68; 95% CI, 1.18-2.41; P<.01 for both) were associated with ≥1 asthma-related hospitalisation.
• Each mmol/mol increase in HbA1c and a HbA1c in the pre-diabetic or diabetic range were significantly and inversely associated with:
  • FEV₁ (β coefficient: −0.015 [95% CI, −0.021 to −0.010] and −0.210 [95% CI, −0.328 to −0.093], respectively);
  • FVC (β coefficient: −0.015 [95% CI, −0.020 to −0.010] and −0.227 [95% CI, −0.331 to −0.124], respectively); but not 
  • FEV₁/FVC ratio (β coefficient: −0.003 [95% CI, −0.008 to 0.002] and −0.044 [95% CI, −0.143 to 0.056], respectively).

Limitations

• Lack of data on potential confounders.
• Possibility of misclassification of chronic obstructive pulmonary disease as asthma.

Yang G, Han YY, Forno E, Yan Q, Rosser F, Chen W, Celedón JC. Glycated hemoglobin A1c, lung function, and hospitalizations among adults with asthma. J Allergy Clin Immunol Pract. 2020 Jun 19 [Epub ahead of print]. doi: 10.1016/j.jaip.2020.06.017. PMID: 32569755. Abstract.

This clinical summary first appeared on Univadis, part of the Medscape Professional Network.