Newly initiated cardiovascular medication and short-term risk of unintentional poisoning among Swedish middle-aged and older adults: A national register-based case-crossover study

BACKGROUND: Although some studies have shown the average side effects of cardiovascular medication, the short-term effect after newly initiated cardiovascular medications has not been studied in any detail. We aim to determine the effect of newly initiated cardiovascular medications resulting in unintentional poisoning and to identify those at high risk. METHODS: A case-crossover design was used. From the Swedish National Patient Register, a total of 9,354 persons aged ≥ 50 and hospitalized with a first event of unintentional poisoning between July 2006 and September 2018 were identified. Through linkage to the Prescribed Drug Register, exposure to newly initiated cardiovascular medication during the case period (1-28 days prior to the onset date of unintentional poisoning) was compared with that in a corresponding control period (113-140 days prior to the onset date). Conditional logistic regression was used to determine the associations in total, for different time periods as well as by age, sex, underlying comorbidity, and use of other medications. RESULTS: Newly initiated cardiovascular medications were associated with a higher risk of unintentional poisoning, especially during the first week after initiation (odds ratio [OR]=1.39), (95% confidence interval [CI]=1.08-1.79). The risk of unintentional poisoning was comparable across age groups, sex, underlying comorbidities, and medications with OR (95% CI) ranging from 1.15 (0.75-1.74) to 2.00 (1.15-3.47). CONCLUSION: This large population-based case-crossover study showed that newly initiated cardiovascular medication is associated with an increased risk of unintentional poisoning, particularly during the first week after initiation. The risk is comparable across age, sex, underlying comorbidity, and medications.