Evaluation of Appropriateness and Interpretation of Serum Theophylline Assays

Abstract

A drug utilization review of serum theophylline assays was undertaken to: (1) evaluate the prescriben' usage and interpretation of serum theophylline levels (STLs), and (2) calculate the cost of inappropriate assays. Criteria for appropriate use and interpretation were defined by an audit committee and approved by the chief medical resident. STLs were evaluated on medicine patients for a one-month period. Results of 102 levels ordered showed that 47 percent were inappropriate. The reasons cited most often for inappropriateness were: (1) previously-known STLs with no reason to expect a change in subsequent levels (26 percent); and (2) STLs drawn prior to steady state (12 percent). None of the levels evaluated had a request entered for the sampling time to be recorded. STLs were interpreted with the same degree of accuracy regardless of whether they were ordered appropriately. Results from this study suggest significant cost savings can be realized if physicians' ordering habits are corrected.