Suppressive effects of long-term treatment with inhaled steroids on hypothalamic-pituitary-adrenal axis in asthma

Purpose: Long-term treatment with inhaled steroids (ICS), especially fluticasone that developed lately, may suppress the hypothalamic-pituitary-adrenal (HPA) axis. This study investigated the relationship between ICS use and HPA axis suppression in asthmatics under ICS treatment for average 4.5 years. Methods: The medical records of 129 adult asthmatics who received ICS treatment for 6 months or more and underwent a corticotropin stimulation test from January 2005 to August 2013 were retrospectively reviewed. Results: The patients received ICS only (n=87) were found to have an abnormal response to the corticotropin test in as high as 32.2%, and those received ICS in combination with oral steroids (n=42) had a significantly higher prevalence of the response (71.4%, P<0.001). Abnormal responses to corticotropin occurred depending on ICS daily doses (low, n=8, 12.5%; medium, n=19, 36.8%; high, n=102, 49.0%; X-2=4.384, P=0.036). Among the subjects received ICS only, nasal steroid doses (P=0.016) but not ICS doses (P=0.159) were significantly higher in those with abnormal responses than the others. Among all the subjects, oral steroid use (odds ratio [OR], 4.27; 95% confidence interval [CI], 2.35-11.80; P<0.001) and nasal steroid dose (OR, 1.02; 95% CI, 1.00-1.04; P=0.015) were significant risk factors for HPA axis suppression. Conclusion: One-third of asthmatics under long-term treatment with ICS showed a suppression of the HPA axis in a dose-dependent manner. Oral or nasal steroid use may be a risk factor for the suppression. However, since our results may have been overestimated due to subject selection bias, further prospective case-control studies are warranted.