National study of prescription poisoning with psychoactive and nonpsychoactive medications in Medicare/Medicaid dual enrollees age 65 or over

Short-Term Risk of Unintentional Poisoning After New Initiation of Central Nervous System Medications in Swedish Older Adults: A Register-Based Case-Crossover Study

Introduction

Medications acting on the central nervous system (CNS) are common causes of medication-related unintentional poisoning. Little is known about the short-term effects of CNS medications on unintentional poisoning.

Objective

This study aims to determine the short-term association between newly prescribed CNS drugs and unintentional poisoning.

Methods

We conducted a register-based case-crossover study of 9354 patients (age ≥ 50 years) with first-time hospitalization for unintentional poisoning in Sweden between 1 July, 2006 and 30 September, 2018. Newly initiated CNS medication was identified based on dispensations from the Swedish Prescribed Drug Register during 28 days prior to the unintentional poisoning event and compared with dispensations during an equally long control period. Conditional logistic regression was used to estimate the odds ratio and 95% confidence intervals.

Results

After a newly initiated CNS treatment, we found an increased risk of unintentional poisoning during the following 2 weeks with an odds ratio (95%) being 2.52 (1.98–3.21) and 1.47 (1.08–2.00) for the first and second week, respectively. The risk was elevated in all sub-groups but to a different degree with odds ratio ranges of 1.73–2.47 by age, 1.91–2.21 by sex, 1.40–2.30 by Charlson Comorbidity Index, 2.00–2.07 by neuropsychiatric comorbidity, and 1.63–2.82 by number of other medications.

Conclusions

The risk of unintentional poisoning doubles in 2 weeks following a new initiation of CNS drugs and the risk is increased across a range of population groups. Clinicians should carefully monitor signs of poisoning after such initiation among not only multimorbid older adults but also those with less comorbidity and polypharmacy.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40264-022-01197-w.

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.