Methodological variability in detecting prescribing errors and consequences for the evaluation of interventions.

PURPOSE

To compare four methods of detecting prescribing errors (PE) in the same patient cohorts before and after an intervention (computerised physician order entry; CPOE) and to determine whether the impact of CPOE is identified consistently by all methods.

METHODS

PEs were identified using (1) prospective detection by ward pharmacist; (2) retrospective health record review; (3) retrospective use of a trigger tool and (4) spontaneous reporting over two separate 4-week periods on one surgical ward in a UK teaching hospital.

RESULTS

We reviewed 93 patients pre- and 114 post-CPOE. Using all four methods, we identified 135 PE (10.7% of all medication orders) pre-CPOE, and 127 (7.9%) post-CPOE. There was little overlap in PE detected by the different methods: prospective detection identified 48 (36% of all PE) pre- and 30 (24%) post-CPOE; retrospective review (RR) revealed 93 (69%) pre- and 105 (83%) post-CPOE, trigger tool 0 pre- and 2 (2%) post-CPOE and spontaneous reporting 1 (1%) pre- and 1 (1%) post-CPOE. The calculated relative reduction in risk of PE was 50% using prospective data, 12% with RR and 26% using data from all four methods.

CONCLUSIONS

In this study, each method predominantly identified different PE. A combination of methods may be required to understand the true effectiveness of different interventions.