Objective This study analyses patterns in reporting rates of medication errors, rates of medication errors with harm, and responses to the Safety Attitudes Questionnaire (SAQ), all in the context of four cultural and three system-level interventions for medication safety in an intensive care unit.

Methods Over a period of 2.5 years (May 2007 to November 2009), seven overlapping interventions to improve medication safety and reporting were implemented: a poster tracking ‘days since last medication error resulting in harm’, a continuous slideshow showing performance metrics in the staff lounge, multiple didactic curricula, unit-wide emails summarising medication errors, computerised physician order entry, introduction of unit-based pharmacy technicians for medication delivery, and patient safety report form streamlining. The reporting rate of medication errors and errors with harm were analysed over time using statistical process control. SAQ responses were collected annually.

Results Subsequent to the interventions, the reporting rate of medication errors increased 25%, from an average of 3.16 to 3.95 per 10 000 doses dispensed (p<0.09), while the rate of medication errors resulting in harm decreased 71%, from an average of 0.56 to 0.16 per 10 000 doses dispensed (p<0.01). The SAQ showed improvement in all 13 survey items related to medication safety, five of which were significant (p<0.05).

Conclusion Actively developing a transparent and positive safety culture at the unit level can improve medication safety. System-level mechanisms to promote medication safety are likely important factors that enable safety culture to translate into better outcomes, but may be independently ineffective in the face of poor safety culture.