Background About 40% of severe asthmatics require maintenance oral corticosteroids (OCS) for disease control. However, significant proportion of these patients continues to have poor disease control due to OCS unresponsiveness or non-adherence (Gamble 2009).
Methods Using a validated in-house developed liquid chromatography/mass tandem spectrometry (LQ/MSMS), we conducted spot measurement of serum prednisolone, prednisone and cortisol in 111 patients attending our severe asthma clinic over a 12 months period. Patients not on maintenance OCS comprised the control group. Suppressed cortisol (20nmol/l, were considered as compatible with adherence to OCS, whilst unsuppressed cortisol and undetectable prednisolone were considered as non-adherent. For validation purposes the test was repeated multiple times in few cases.
Results The prednisolone/cortisol spot test was conducted on 111 patients (79% females) with 44 (40%) were not on regular OCS (control group) and 67 (60%) on maintenance OCS. The spot test revealed non-adherence in 27/67 (40%) of patients and adherence in 40/67 (60%) of patients. The prednisolone/prednisone/cortisol assays were similar in non-adherent group and non-OCS group (figure). The mean daily prednisolone dose was 16.3, 20.1, and 0.0 mgs in the adherent, non-adherent and non-OCS groups respectively. Non-adherent patients had lower BMI, and higher exacerbations frequency, blood eosinophil count, and fraction exhaled nitric oxide than OCS adherent group. The non-adherent group resembled more the non-OCS group with regard to aforementioned parameters.
We conclude that this prednisolone/cortisol spot test is reproducible and diagnostic of non-adherence to OCS in 40% of patients on maintenance OCS, and should be routinely measured in severe asthma clinics to improve patients management.
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