Audit of Theophylline Plasma Level Monitoring in a Pediatric Hospital

Abstract

Theophylline assays performed in a children's hospital were audited, focusing particularly on distribution of plasma concentration values, interpretation of the assay result, appropriateness of the advice conveyed to the physician, and the response to this advice. Assays performed by a multidisciplinary therapeutic drug monitoring (TDM) service during a 1-month period in 1988 and again in 1992 were chosen for review. Theophylline concentration in plasma was quantified by fluorescence polarization immunoassay. Medical technologists interpreted results and made specific recommendations concerning dose changes and/or need for follow-up assays on 48.5 (1988 survey) and 37.9% (1992 survey) of results. Review of these recommendations revealed that only approximately 1% could have been improved or were incorrect. Physician compliance with dose change recommendations was similar in both surveys (chi 2 = 0.16, p = 0.7), with recommendations being followed on 75.9 (1988) and 73.3% (1992) of occasions. Compliance with recommendations for ordering additional samples at specific times also was similar between the two surveys (chi 2 = 2.06, p = 0.15), with recommendations being followed on 75 (1988) and 87.2% (1992) of occasions. Overall, combining the data for both surveys, (a) significantly more out-patients than in-patients (69.2 versus 27.8%, respectively) were subtherapeutic, (b) significantly fewer out-patients than in-patients (27.6 versus 70.2%, respectively) were within the therapeutic range (chi 2 = 33.7, p < 0.001), but (c) numbers (2-4%) of potentially toxic results within the two groups were similar.