Medication use as a risk factor for inpatient falls in an acute care hospital: a case-crossover study

Abstract

Aims: The present study aimed to evaluate the associations between medication use and falls and to identify high risk medications that acted as a trigger for the onset of falls in an acute care hospital setting.

Methods: We applied a case-crossover design wherein cases served as their own controls and comparisons were made within each participant. The 3-day period (days 0 to -2) and the 3-day periods (days -6 to -8, days -9 to -11 and days -12 to -14) before the fall event were defined as the case period and the control periods, respectively. Exposures to medications were compared between the case and control periods. Odds ratios (OR) and 95% confidence intervals (CI) for the onset of falls with respect to medication use were computed using conditional logistic regression analyses.

Results: A total of 349 inpatients who fell during their hospitalization were recorded on incident report forms between March 2003 and August 2005. The initial use of antihypertensive, antiparkinsonian, anti-anxiety and hypnotic agents as medication classes was significantly associated with an increased risk of falls, and these ORs (95% CI) were 8.42 (3.12, 22.72), 4.18 (1.75, 10.02), 3.25 (1.62, 6.50) and 2.44 (1.32, 4.51), respectively. The initial use of candesartan, etizolam, biperiden and zopiclone was also identified as a potential risk factor for falls.

Conclusions: Medical professionals should be aware of the possibility that starting a new medication such as an antihypertensive agent, including candesartan, and antiparkinsonian, anti-anxiety and hypnotic agents, may act as a trigger for the onset of a fall.

Figure 1

Definition of risk, control and wash-out periods in the present case-crossover study. The 3-day period (days 0 to −2) just before any fall event was defined as the case period based on the elimination half-life of the prescribed medications. The three control periods for each case were estimated to increase the consistency of comparable controls and to enhance the robustness of the analyses. The 3-day periods (days −6 to −8, days −9 to −11 and days −12 to −14) before the fall event were defined as the control period. The 3-day period (days −3 to −6) before the fall event between the case period and the control period was assigned as the wash-out period