Development strategy and potential impact on medication safety for clinical rules: the lithium case

Abstract

Introduction: Prescribing, administration and monitoring of drugs are complex and error sensitive processes. Physicians have to take into account many drug- and patient specific characteristics continuously during therapy. Appropriate use of information technology, especially the introduction of clinical decision support systems (CDSS) can substantially reduce medication error rates and improve patient safety [1, 2]. Strategies for the development of clinical rules used in these CDSS systems are not available. Purpose: The aim of this study was: (1) to evaluate a strategy for the development of clinical rules and (2) to determine the potential impact on medication safety of these clinical rules. Lithium therapy was chosen as a test concept. Methods: For the development of clinical rules we followed a Plan – Do – Check – Act (PDCA) cycle with a panel of experts. Standard literature sources were screened for patient characteristics, monitoring parameters and other characteristics that have to be taken into account during lithium therapy. We translated this information into clinical rules for the CDSS system Gaston®# # Gaston®: P.A.de Clerq, MEDECS b.v. http://www.medecs.nl (plan). These rules were retrospectively tested on patients admitted to the Catharina-hospital Eindhoven in 2004 and 2005 using lithium (do). Signals were checked in the electronic patients record on: (1) appropriateness and (2) the action undertaken by the physician compared to the action warranted by the CDSS. For every rule the Positive Predictive Value (PPV) was determined: number of appropriate signals produced /total number of signals. When the action undertaken was not right according to the clinical rules we scored this as a Potential Adverse Drug Event (PADE) (check). Results were discussed with an expert panel and the clinical rules adjusted according their consensus (act). Results: The PDCA strategy with an expert panel resulted in a package of clinical rules for patients starting with, or using lithium therapy. To design the definite clinical rules the input of the expert team was essential, because literature left to much room for interpretation in clinical practice. The clinical rules were tested on 38 patients starting with and 93 patients using lithium in 2004 or 2005. The PPV’s of these clinical rules varied from 0.2 to 1.0 (mean 0.8). We identified 81 PADE’s in 71 patients, that could have been prevented when the CDSS would have been active. Most important PADE’s were: 1) omitted determination of lithium plasma levels after reduction of creatinin clearance < 50 ml/min (4 times) and starting or stopping of an interacting drug (17 times); 2) determination of lithium, Thyroid Stimulating Hormone (TSH), leucocyte and calcium plasma levels every 3 or 6 months (resp. 17, 6, 2 and 4 times). An important limitation for the creation of higher PPV’s and for the identification of PADE’s was the lack of outpatient data. Further research is needed to show that this system is clinically applicable. Conclusion: A strategy of PDCA combined with an expert panel is a prerequisite for the development of clinical rules for drugs in a CDSS. We demonstrated that a CDSS is able to identify patients with potential adverse drug events. Therefore we conclude that application of CDSS can have a relevant impact on medication safety in clinical practice.