In this nationwide population-based study, we demonstrated that the incidence of intoxicated or severe intoxicated patients in Taiwan declines significantly between 2006 and 2013 (annual percentage change decreased by 4.7% & 4.2%). However, the mortality, hospital LOS, and daily medical costs related to intoxication events remained similar during this period. Another major finding was that the risks for mortality from intoxication were higher in males (58% increased risk), the elderly (303%), and those with a previous psychiatric illness (30%).
We found that intoxication events accounted for 8.8 per 1000 ED admissions, similar to previous studies. In particular, intoxication events accounted for about 1 to 7 per 1000 ED admissions in Spain and Oslo (1, 4). Although Taiwan had a slightly greater incidence, its annual percentage change decreased by about 4% between 2006 and 2013. We found that most patients in Taiwan who had intoxication events were directly discharged from the ED, similar to other studies (Taiwan: 76%; National Poison Data System [NPDS]: 47–51%; other studies: 55–79%) (1, 2, 4–12). These patients presumably had minor intoxication events (13), received antidotes promptly, rapidly eliminated the toxins, or absorbed smaller amounts of toxins.
In contrast, it is not similar for patients severely intoxicated. In particular, 36% of patients with severe intoxication were transferred to different hospitals, about 3.5-times more often than patients who had intoxication. The possible reasons for this include the lack of toxicologists, the need for specific laboratory tests or antidotes, or the presence of a serious condition that required intensive care. Moreover, 81.8% (N = 1567) of our severely intoxicated patients were admitted to an ICU. Among severely intoxicated patients who were not admitted to an ICU, only 36.4% were ever admitted to wards. This may be because of a lack of ICU beds, because the patient stabilized or expired quickly while in the ED, or because the patient signed a do-not-resuscitate order or refused intensive care.
Our overall in-hospital mortality rate was much higher than reported in other countries (Taiwan: 2.6%, other countries: 0.1–1.3%), as was our mortality rate from severe intoxication (Taiwan: 21.6%, other countries: 2–9%) (1, 2, 14, 15). The most likely reason is the higher proportion of severe intoxication events or greater severity of intoxication in our population (5–13, 16–18). Our mean ICU stay (3 days) and hospital LOS (7 days) was longer than reported in studies from The Netherlands and Hong Kong (ICU: 0–1.3 days; hospital LOS: 1–3 days) (14, 18, 19). If we calculate the ratio between the number of patients receiving different in-hospital treatments to patients receiving mechanical ventilation, the ratio of the patients receiving inotropic agent to patients receiving mechanical ventilation was 0.848:1. The ratios of the number of patients who received CPR and hemodialysis to the number who received intubation were 0.228:1 and 0.309:1, respectively. Analysis of data from the NPDS (5–12) for intoxicated patients older than 20 years between 2006 and 2013 indicated that the ratios of the numbers of patients who received an inotropic agent, CPR, and hemodialysis to the number of patients who received mechanical ventilation were 0.269:1, 0.045:1 and 0.125:1, respectively. The need for more intensive interventions in our population may be because highly toxic pesticides, such as paraquat, were available in Taiwan during study period. This may also account for the higher mortality in our population (20–22). Because our population had longer ICU stays, higher percentages of patients who received aggressive medical or resuscitation treatments, and greater exposure to highly toxic pesticides, it is reasonable that our population also had a higher percentage of patients with severe intoxication.
Our subgroup analysis of sex, age, and previous psychiatric illness indicated that females were 9% more likely to present with intoxication, but males were 32% more likely to present with severe intoxication. Previous studies from the United States, Iran, and Nordic countries reported similar patterns (5, 23–26). However, our examination of patients with severe intoxication indicated that sex was unrelated to survival. The incidence of severe intoxication among different age groups also varied in previous studies (17, 23, 27). We found that elderly patients were more likely to die from severe intoxication. In particular, our subgroup analysis demonstrated that the middle-age group had the highest incidence of severe intoxication, but the elderly group had the highest mortality from severe intoxication. Previous studies showed that geriatric patients were intoxicated mostly by accident (28). However, they were also more susceptible to intoxication because they tend to have more comorbidities (29).
We found that patients with previous psychiatric illnesses were more likely present to an ED with intoxication, have more severe intoxication, and die from intoxication. These results are consistent with previous studies that patients with psychiatric illness had higher risks of drug overdose (30–33). However, in our study these patients had longer hospital LOS, but lower daily medical expenses. We are uncertain about the reasons for their lower medical expenses. In fact, it seems likely that many of these patients required long periods of psychiatric adjustment, evaluation, or admission to a psychiatric ward before resolution because they have an increased risk of a subsequent episode of self-harm or intoxication (34–36).
Strengths and limitations
A major strength of this study is that it was a nationwide population-based study which examined the incidence and clinical outcomes of intoxication events in adults who ever visited the ED, and the temporal trend change from 2006 to 2013. We also evaluated different subgroups of patients, based on sex, age, and psychiatric illness. Nevertheless, our study had some limitations. First, we extracted data from an insurance claims database, and this did not provide details regarding the history of intoxication events, personal history, and laboratory results. Thus, we were unable to identify the names or amounts of different intoxicants, nor the reasons for ingestion. Regardless, our analysis from the insurance claims database was reliable and provided a nationwide perspective. Second, we did not have all relevant clinical data for the patients, such as body temperature, heart rate, blood pressure, and level of consciousness. Instead, we classified patients with severe intoxication based on the treatment received. Although we did not classify patients with transiently unstable vital signs as severe cases, we considered intoxicated patients who required an inotropic agent, mechanical respiratory support, CPR, or ICU admission as being truly severe. Third, because we identified intoxication events based on ICD9 codes and the antidotes administered, there may have been some misclassification. However, previous studies based on similar databases showed reliable results (22, 37–42). Our current research thus provides an overview of intoxication events in Taiwan between 2006 and 2013. We are planning the development of an intoxication registry at the national level with associated parameters for future studies.