Bastiaan Sallevelt

41 Performance of a trigger tool for detecting adverse drug reactions Data analysis Descriptive data analysis and Cohen’s kappa test statistic was performed with IBM SPSS Statistics v. Results Study population A random selection of 589 out of all 1366 patient admissions to the geriatric department through the ED between 01-01-2011 and 01-08-2017 was screened for eligibility. From this selection, 378 admissions met our inclusion criteria (i.e. age ≥70 and polypharmacy), of which 33 admissions were excluded because they were not a patient’s first admission within the study period. The study population of 345 patients had a median age of 84 (IQR 79–88). The median number of drugs at admission was 10 (IQR 8–13), and 61% of the patients were female. Subsequently, admission letters of these patients were screened for the presence of trigger-drug combinations according to the ADR trigger tool. Out of 345 eligible patients, 253 (73%) had at least one trigger-drug combination present. In 52% (178/345) of the total study population, at least one ADR with a causal relationship considered possible, probable or certain was present. Number of trigger-drug combinations The total number of trigger-drug combinations was 941, with a median of 3 (IQR 2–5) and a maximum of 16 trigger-drug combinations per patient. Fall (32.4%), delirium (24.0%), renal insufficiency / dehydration (16.2%) and hyponatraemia (13.5%) were the most frequent clinical events and covered 86.3% of all identified trigger-drug combinations (Table 2). Causality assessment and PPV Of the 941 identified trigger-drug combinations, 41.8% (n = 393) were adjudicated as an ADR by the two appraisers in 178 patients. More than a quarter (27.0%) of all 941 trigger-drug combinations were considered as possible ADRs, 12.3% were adjudicated as probable ADRs, and 2.4% as certain ADRs. In 57.0% of the triggerdrug combinations, an ADR was considered as unlikely, and the other 1.3% of the combinations were unclassifiable (Table 2). Inter-rater agreement for causality assessment of ADRs was substantial (κ=0.61-0.80) with a Cohen’s kappa of 0.76 [23]. In total, causality scores of 163/941 trigger-drug combinations differed between the adjudicators, with a difference of only one WHO-UMC category in 91.1% of the 2