Adrenal insufficiency in asthma patients – Who is at risk?

Abstract

Corticosteroids play a central role in asthma management. Previous work suggests that inhaled corticosteroid (ICS) use is a risk factor for adrenal insufficiency (AI) (Woods et al. Eur J Endocrinology 2015 173, 633-642) however there is very little research into the incidence of, or risk factors for AI in adult asthma patients. We present data examining this issue in a specialist adult asthma clinic.

We retrospectively examined the notes of all patients investigated for AI in our clinic from 2010-2015. Patients were tested if presenting with relevant signs and symptoms or with atypical symptoms responsive to corticosteroids.

185 patients were tested. 35 (19%) had AI, defined by an undetectable baseline cortisol or cortisol rise to <500nmol/L in short Synacthen/glucagon stimulation test. In 19 (10.2%) of these cases, AI was attributable solely to ICS treatment. The remaining 16 had an additional cause identified.

Compared to patients with normal cortisol, those with AI were taking higher dose ICS (p<0.05). There was no significant difference in incidence of AI between ICS formulations. Factors associated with risk of AI included co-prescription of cytochrome P450 inhibitors (OR 10.17, 95% CI 2.47–41.80), systemic steroid treatment (OR 5.35, 95% CI 2.3–12.38) and ICS beclomethasone equivalent dose (BDP) >2000 mcg (OR 3.12, 95% CI 1.29–7.57).

Our results demonstrate that adrenal insufficiency is a significant problem in asthma clinic affecting almost 20% of those tested. Risk of AI increases with higher dose ICS irrespective of formulation.

We propose routine testing for AI based on symptoms and risk factors in all patients taking ICS. Further work is ongoing to assess the effect of AI treatment on asthma control.