Use of Short Synacthen Testing to Detect Iatrogenic Adrenal Insufficiency among Severe Asthma Patients

Introduction: Adrenal insufficiency (AI) secondary to long-term oral corticosteroids (OCS) – both daily maintenance (mOCS) and short burst (sbOCS) – is an under-recognised complication of severe asthma treatment (Gurnell, M. et al. J Int Med. 2021;290(2):240-256). We describe outcomes of short synacthen testing (SST) for iatrogenic AI over 3 years in our severe asthma service. Methods: We reviewed patients who underwent SST from 01/04/19–01/04/22. Patients with AI were compared to those without, assessing for predictive factors. Data were collected on outcome following SST. Results: 89 patients (72 on biologics) with history of mOCS and/or recurrent sbOCS use underwent SST; 38 had confirmed AI. Patients with AI had a higher mOCS dose than those without (5.88 v 4.01 mg/day, p=0.002). Other physiological factors were not significantly different. Equal numbers of patients with and without AI reported AI-related symptoms prior to SST. Following SST, 21/38 patients with AI were switched to hydrocortisone therapy, while 17 remained on mOCS. 25/51 patients without AI were weaned off mOCS, while 15/51 had an ongoing mOCS wean at time of writing. Conclusion: Over 40% of our cohort had AI diagnosed after SST. Higher daily mOCS dose appears to increase risk but symptoms of AI, or absence thereof, were not predictive of AI; systematic screening for all patients with OCS exposure sufficient for biologics is prudent.