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A cross‐sectional study evaluating the relationship between cortisol suppression and asthma control in patients with difficult asthma
Author(s) -
AbuRuz S.,
Heaney L. G.,
Millership J.,
Gamble J.,
McElnay J.
Publication year - 2007
Publication title -
british journal of clinical pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.216
H-Index - 146
eISSN - 1365-2125
pISSN - 0306-5251
DOI - 10.1111/j.1365-2125.2006.02745.x
Subject(s) - asthma , medicine , creatinine , urinary system , urine , correlation , physical therapy , mathematics , geometry
Aim To examine the relationship between cortisol suppression and asthma symptoms in patients with difficult asthma. Methods Patients, referred to a specialist difficult asthma service and who fulfilled the criteria for difficult asthma, were recruited to the study in a sequential, unselected manner. At each clinic visit, all patients completed a validated asthma control questionnaire. For measuring cortisol suppression, early morning urinary cortisol [corrected for creatinine to give urinary cortisol creatinine ratio (UCC ratio)] was used. The urine samples were collected and stored at − 70 °C until ready for analysis. Urinary cortisol was extracted (solid‐phase extraction) and analysed using high‐performance liquid chromatography. The Pearson correlation coefficient was used for correlation analysis while t ‐tests were used for between‐group differences for normally distributed data. If the data were not normally distributed, nonparametric statistics were used. A P ‐value < 0.05 was considered statistically significant. Results During the study period all the patients who attended the difficult asthma clinic and fulfilled the criteria for difficult asthma ( n = 66) agreed to take part in the study. There were moderate to strong and significant associations between several measures of asthma control and UCC ratio. The correlation coefficient with five indicators of asthma control ranged between 0.3 and 0.5 ( P < 0.05). Conclusions We have demonstrated a relationship between cortisol suppression and asthma control in difficult asthmatics on high‐dose steroid therapy. We have proposed a model based on the relationship between symptom control and cortisol suppression, whereby both adherence and therapeutic adjustments could potentially be made. A properly controlled prospective clinical trial should examine the utility of this approach in clinical practice.