Preplanned Studies: Characteristics of Poisoning Cases Admitted to Outpatient and Emergency Department — China, 2019

Poisoning remains a serious global public health concern (1). The World Health Organization (WHO) reported that in 2019, unintentional poisoning was responsible for an estimated 84,278 deaths worldwide. Furthermore, approximately 20% of suicides globally are attributed to pesticide self-poisoning, a trend most prevalent in rural, agricultural regions of low- and middle-income countries (2). In China, poisoning is a leading cause of mortality among individuals aged 1 to 44 years. Data from 2020 indicates that unintentional poisoning ranked as the eighth leading cause of death for those aged 1–4 and 15–29, and the ninth for those aged 5–14 and 30–44 (3). Poisoning also constitutes a common reason for emergency hospital visits in many nations (1). Despite its prevalence, comprehensive knowledge on the epidemiology of poisoning incidents in emergency departments is lacking in China. To bridge this informational shortfall, we utilized data from the national injury surveillance system to investigate the epidemiological characteristics of poisoning cases in outpatient and emergency settings within China for the year 2019.

The research included data on poisoning cases reported by a network of 252 national surveillance hospitals connected to the national injury surveillance system (NISS) from January 1 to December 31, 2019. The NISS, established by the Ministry of Health, acts as an efficient information gathering system capturing the epidemiological characteristics of patients admitted to outpatient and emergency departments across China for injuries. The distribution of surveillance sites and the methodology for data collection have been thoroughly detailed in previously published research (4).

For this study, we employed the “clinical diagnosis” text variable from the reported poisoning cases to recode the categorization of the substances involved. This recoding was founded on a coding dictionary developed for the study, which was informed by resources such as the Poison Information Package for Developing Countries (INTOX). It is important to note that the term “poisoning” within the scope of this research is confined to instances of acute poisoning and does not encompass chronic poisoning or pathological conditions such as allergic or infectious diseases induced by external substances.

Descriptive analysis was conducted on demographic information, occurrence information and clinical information of poisoning case by age, gender, intent and type of substance exposed. Chi-square test was used to compare the constituent ratios, P<0.05 was considered to be significant. Software SAS (version 9.4, SAS Institute Inc., Cary, USA) was used for statistical analysis.

In 2019, the NISS recorded 31,382 cases of poisoning, predominantly among males (19,723 cases, 62.85%) and individuals aged 25–44 (13,849 cases, 44.13%). The majority of these poisoning incidents were unintentional, accounting for 82.60% of the total cases. The intent behind the poisonings varied significantly by age group (χ²=355.73, P<0.05) and gender (χ²=743.48, P<0.05). The proportion of poisonings with self-harm or suicidal intent was highest in the elderly aged 65 and older (14.57%) among all age groups, and it was higher in females (11.92%) than in males (4.12%).

The occurrences of poisoning were distributed evenly throughout all seasons but were slightly higher in winter (27.83%) and summer (27.40%). Home was the most frequent location for poisoning incidents among females (64.98%) in contrast to males (41.53%) (χ²=1766.33, P<0.05). Severely affected cases made up 52.11% of the total, with moderate injuries comprising 39.90%. A significantly higher proportion of severe poisoning was observed in children aged 0–4 years (63.17%) (χ²=1024.35, P<0.05), and was more common in males (53.66%) than in females (49.48%) (χ²=145.81, P<0.05).

Post-treatment outcomes, including observation, admission, or transfer to another hospital, were noted in 57.46% of poisoning cases, and there were 141 fatalities (0.45%). The disposition of poisoning cases demonstrated significant differences when analyzed by age group (χ²=647.18, P<0.05) and gender (χ²= 275.49, P<0.05) (Table 1).

In 2019, out of 31,382 reported poisoning incidents recorded in the NISS database, 96.46% were successfully categorized by identified substances after undergoing re-coding. The predominant substances involved in poisoning cases presenting to outpatient and emergency departments were alcohol (56.38%), medications (14.21%), and pesticides (9.78%). The analysis revealed statistically significant variations in the distribution of involved substances by age group (χ²=7243.55, P<0.05), by gender (χ²=3939.79, P<0.05), and by intention (χ²=6,119.54, P<0.05). The leading substances exposed of child poisoning were medications both in the 0–4 age group (42.08%) and 5–14 age group (25.68%). Similarly, among seniors aged 65 and older, medications (24.51%) were the leading cause of poisoning. Alcohol-related poisonings constituted 69.5% of the cases in males, which was more than twice the rate observed in females. With regard to the intent of poisoning, alcohol was implicated in 61.02% of unintentional poisonings, while medications were involved in 46.19% of cases with suicidal intent (Table 2).

Throughout the year, seasonal trends are evident in the incidence of various poisoning types. Drug poisoning peaked during the spring, accounting for 27.16% of cases, while pesticide poisoning and incidents involving toxic flora and fauna were most frequent in summer, representing 32.68% and 58.37% of cases, respectively. Winter saw the majority of alcohol poisoning, carbon monoxide (CO) poisoning, and chemical poisoning cases, with prevalences of 28.94%, 59.87%, and 33.45%, respectively.

Location-wise, alcohol poisoning was primarily concentrated in commercial and service areas, constituting 42.56% of incidents. Conversely, other poisonings predominantly occurred in residential settings. In terms of post-incident care, alcohol poisoning cases frequently resulted in discharge following treatment, comprising 53.31% of the outcomes. However, other poisoning types were commonly subject to observation, admission, or transfer (Table 3).