Development and evaluation of a computerised clinical decision support system for switching drugs at the interface between primary and tertiary care

Abstract

Background: Upon admission to a hospital patients' medications are frequently switched to alternative drugs compiled in so called hospital drug formularies. This substitution process is a laborious and error-prone task which should be supported by sophisticated electronic tools. We developed a computerised decision support system and evaluated benefit and potential harm associated with its use.

Methods: Based on a multi-step algorithm we identified drug classes suitable for exchange, defined conversion factors for therapeutic interchange, built a web-based decision support system, and implemented it into the computerised physician order entry of a large university hospital. For evaluation we compared medications manually switched by clinical pharmacists with the results of automated switching by the newly developed computer system and optimised the system in an iterative process. Thereafter the final system was tested in an independent set of prescriptions.

Results: After iterative optimisation of the logical framework the tool was able to switch drugs to pharmaceutical equivalents and alternatives; in addition, it contained 21 different drug classes for therapeutic substitution. In this final version it switched 91.6% of 202 documented medication consultations (containing 1,333 drugs) automatically, leaving 8.4% for manual processing by clinical professionals. No incorrect drug switches were found.

Conclusion: A large majority (>90%) of drug switches performed at the interface between primary and tertiary care can be handled automatically using electronic decision support systems, indicating that medication errors and workload of healthcare professionals can be considerably reduced.

Figure 1

Switch Algorithm. Standardised multi-step algorithm to translate a drug regimen into appropriate alternatives contained in a hospital formulary (modified from [1]).

Figure 2

Substitution of therapeutic equivalents. Switch of a drug to a therapeutic equivalent within the same drug class and corresponding dose adjustment using dose conversion factors.

Figure 3

Screenshot: CDSS for automatic switching of drugs. Drugs prescribed to the patient before admission are listed on the left and the correspondingly switched drugs are shown on the right. The figure shows five examples of drug switches originating from the single steps of the algorithm (step 1–5). In example 2 an additional warning is displayed informing about differing indications of the switched drugs, in example 3 a combination drug is switched to two single agents. In example 4, the switch to a therapeutic equivalent required dosage adjustment (20mg simvastatin qd → 40mg pravastatin qd), and in example 5, no alternative could be suggested.

Figure 4

Results of the evaluation. Results of the pilot and final evaluation of the CDSS (computerised decision support system). The evaluation was performed by comparing the switch suggestions of the CDSS with those of the clinical pharmacists (CP). CP = CDSS: Drugs substituted similarly by CP and CDSS. CP ≠ CDSS: Relevant differences in automatic and manual switching. CP < CDSS: Suggestion of CDSS is better. CP ≈ CDSS: Both suggestions are considered appropriate. CP > CDSS: Suggestion of CP is better. CDSS ok: Suggestion of CDSS correct but inferior to suggestion of CP. CDSS not ok: Suggestion of CDSS inadequate/wrong.