Objective To determine the utility of a tool (TRIGGER-CHRON) for identifying adverse drug events (ADEs) associated with the administration of high-alert medications in elderly patients with multimorbidity and to determine the medications most frequently implicated.

Methods A retrospective observational study was conducted at 12 Spanish hospitals. A random sample of five medical records from each hospital was selected weekly for review over a 12-week period. We included patients aged 65 and over with multimorbidities, hospitalised for >48 hours. ADEs detected by the 32 TRIGGER-CHRON signals and caused by high-alert medications included on the Spanish HAMC list for chronic patients were selected for analysis. Triggers identified and ADEs detected were recorded. The severity and preventability of the ADEs were evaluated. The positive predictive value (PPV) of each trigger was calculated.

Results On 720 charts reviewed, 908 positive triggers were identified that led to the detection of 158 ADEs caused by at least one high-alert medication on the HAMC list. These ADEs occurred in 139 patients (prevalence 19.3/100 admissions). The majority of ADEs were mild and 59.5% were deemed preventable. The drugs most frequently associated with ADEs were corticosteroids, loop diuretics, opioid analgesics and oral anticoagulants. Fifteen triggers had PPVs ≥20%. Six triggers (serum glucose >110 mg/dL, abrupt cessation of medication, oversedation/lethargy, hypotension, adverse reaction recorded and constipation) accounted for 69.8% of the ADEs identified.

Conclusions Applying the TRIGGER-CHRON to hospitalised patients with multimorbidity in 12 Spanish centres allowed detection of one adverse event caused by a high-alert drug for every four patients, which were preventable in a large proportion of patients. This confirms the need to establish interventions that reduce harm with these medications. We believe that TRIGGER-CHRON can be a useful tool to measure this harm and to determine the effects of medication safety improvement programmes as they are implemented.