COMPLIANCE WITH ORAL CORTICOSTEROIDS DURING STEROID TRIALS IN CHRONICAIRWAYS OBSTRUCTION

Background - Corticosteroid trials are an important part of the assess ment of patients with chronic airways obstruction, but false negative results will occur if the treatment is not taken. To determine complia nce low dose phenobarbitone has been used as a marker. Methods - Thirt y six patients referred to a chest clinic for assessment of their airw ays obstruction were studied. They were instructed to take eight capsu les (each containing 5 mg prednisolone and 0.5 mg phenobarbitone) per day for two weeks. The response was assessed by home peak flow monitor ing and clinic spirometric tests. Plasma phenobarbitone levels were me asured after the trial to enable calculation of the dose to plasma con centration ratio (level to dose ratio, LDR) and the result was compare d with the reference range for fully compliant individuals. Results - Five patients defaulted from follow up, 23 had LDR values within the e xpected range, and eight had low LDR values consistent with poor compl iance. The nine patients with steroid responsive disease (>20% improve ment in peak flow or spirometric parameters) all had LDR values in the expected range. Conclusion - Excluding those who defaulted whose comp liance must be questionable, eight (26%) patients did not fully comply with the steroid trial. Not all patients who fail to respond to a two week home steroid trial have a steroid ''unresponsive'' disease.