Patterns of acute poisoning-Five year study from National Poison Control Centre, Karachi, Pakistan

Objective: To identify patterns in cases of acute toxicity reported at an urban poison control centre. Method: The cross-sectional, retrospective study was conducted at the National Poison Control Centre, Karachi, and comprised data from January 1, 2017, to December 31, 2021. Data was collected from the institutional database which is part of the Jinnah Postgraduate Medical Centre, Karachi. Data of all patients diagnosed with acute poisoning was included. Data was analysed using SPSS 22. Results: Of the 4,936 cases reported, 2,449(49.6%) were males and 2,487(50.3%) were females. Pesticide was the most common cause of toxicity 1254(25.4%). Regarding outcomes, 351(7.1%) patients expired, 3,585(72.6%) were discharged after appropriate treatment, 366(7.4%) were given outpatient and psychiatric referrals, and 634(12.8%) patients left against medical advice. Conclusion: The most common agent causing toxicity was pesticides, and overall mortality across the study period was 7.1%.


Introduction
Acute toxicity is a major medical emergency resulting in morbidity and mortality in all age groups 1,2 . According to the World Health Organisation (WHO), poisoning results in an annual loss of 7.4 million years of healthy life globally. Acute poisoning cases have been categorised as the second largest cause of morbidity after road traffic accidents (RTAs) 3 .
Acute poisoning can be intentional or unintentional, the former being more common in adults, while the latter is mostly seen in younger age groups 4 . Data from the American Association of Poison Control Centres (AAPCC) suggests that most common toxicological agents causing poisoning are analgesics, cosmetics, household cleaners, and sedatives/hypnotics/antipsychotics, while European data cites sedatives/hypnotics/antipsychotics, alcohol and carbon monoxide as the most common agents causing poisoning. In underdeveloped and agricultural countries of Asia and Africa, pesticides are most common poisonous substances, followed by medications and household products 5 . In underdeveloped regions of the world, increased incidence of poisoning is the reason for many hospitalisations, and also has an impact on healthcare resources and financial distribution. 6 There are many variations in patterns and causes of poisoning in different geographical regions even within the same country. Recognising these trends and patterns can identify the risk factors and play a vital part in saving lives and reducing the burden on healthcare resources 7 .
Death due to poisoning is regarded as an unnatural death, and requires medicolegal investigation and detailed postmortem examination. Limited work and research has been done in this domain in Pakistan 8 .
The current study was planned to identify patterns in cases of acute toxicity reported at an urban poison control centre.

Materials and Methods
The cross-sectional, retrospective study was conducted at the National Poison Control Centre (NPCC), Karachi, and comprised data from January 1, 2017, to December 31, 2021. After approval from the ethics review board of the Jinnah Postgraduate Medical Centre (JPMC), Karachi, data was retrieved using consecutive sampling technique. Record of all the patients presenting to NPCC with diagnosis of acute poisoning was included, while data of those with any other diagnosis or those with incomplete record was excluded. The diagnosis was based on presenting complaints, history, clinical picture and laboratory findings. The data was anonymised at the time of collection, and only relevant details like age, gender, causative agent of poisoning, date of reporting and outcomes were recorded.
With respect to age, data was divided into four groups; children aged 1-10 years, adolescents aged 11-19 years, adults aged 20-59 years, and elderly aged 60 years or more. Each year was divided into four quarters; 1st quarter from January to March, 2nd quarter from April to June, 3rd quarter from July to September, and fourth quarter from October to December. This was done to asses any seasonal variation.
Data was analysed using SPSS 22. Numerical data was expressed as mean and standard deviation, while the rest was expressed as frequencies and percentages. For categorical data, associations were recorded using chisquare test. P<0.05 was taken as significant.
Significant differences were found when data was analysed with respect to patients' gender (    (Table 5).

Discussion
The study showed a decline in the number of cases of poisoning compared to the first three years, from 2017 to 2019, of the five-year period, which is a finding in contrast to most studies done previously around the world 9 . This decline may be further explored to find out the factors that may be at play. One thing that may also be considered in relation to this finding is that the lockdowns as a result of the coronavirus disease-2019 (COVID- 19) were imposed nationwide intermittently since March 2020, and that could have caused hindrance in reporting to the hospital 10 . Also, there was fear, anxiety and depression instilled in the general population 11 . Aversion to hospital visits owing to the fear of contracting the disease 12 may have played its role in making many healthcare issues, including acute toxicity, to be underreported.
On the other hand, a steady increase in the number of cases was noted from 2017 to 2019. As far as different times of the years are considered, most of the cases were reported between April and June when the climate in the city is mostly warm, a fact also observed in a research conducted in India where maximum number of cases were seen in summers during the months of May, June and July 13 . One of the reasons may be the fact that higher serotonin during summer encourages impulsivity and aggressive behaviour that may influence the decisionmaking capacity and promote suicidal actions within the general population 13 . However, the finding is in contrast with a study done in Ethiopia where most patients reported in December, January and February, which is the winter season 6 .
The male-to-female ratio observed in the current study was almost equal, with female cases being negligibly higher than males and ratio being 1:1. This is a very distinct finding that contrasts with most studies done previously not in Pakistan 14 as well as in Nepal 15 and China 16 . Studies in Bangladesh 17 and India 18 showed greater number of male patients compared to the females. Similarly, in cases of snakebite, alcohol, and cannabis-related toxicity, the number of male patients was higher compared to the females. This can be attributed to cultural practices. like males being more involved in outdoor activities and being more independent within society. Most cases reporting to the NPCC were middle-aged, which is in line with studies in Ethiopia 19 , India 18 and China 16 . This age group is particularly vulnerable due to the fact that people experience greater level of stress while going through the most active part of human life.
Pesticides, benzodiazepines, paracetamol, snakebites, kala PPD, which is an ingredient in locally produced hair dyes, alcohol, cannabis and antiepileptics were the substances causing acute toxicity, while many cases had unknown reasons for the toxicity. Maximum number of patients reported with complaints of poisoning by One distinct significant finding regarding outcomes in the current study was that when different toxic substances were analysed, maximum number of deaths were found to have resulted due to PPD poisoning. It is becoming an emerging trend in Pakistan to use this substance with the intent of self-harm 21 .
Karachi is by far denser than any other city with an urban population of >10 million preceded by Dhaka in Bangladesh and Mumbai in India in this aspect 22 . The current study was conducted at an established publicsector poison control centre at a tertiary care hospital in Karachi, the only facility in the city addressing the needs of poison victims where most patients with poisoning complaints report. The sample size along with five-year duration and the poison centre being the main centre of the city managing such cases add to the strength of the study, and provide substantial ground for assessment of patterns of poisoning in the city making the results and the deductions more reliable.
However, the current study has limitations due to its cross-sectional design as selection bias cannot be ruled out. Besides, inclusion of other private-and public-sector hospitals would have provided a more accurate picture of the scenario prevailing in the city in relation to the issue of acute toxicity. Also, the matter could have been explored more accurately by including routes of poisoning.

Conclusion
The most common agent causing toxicity was pesticides, the number of cases were high in the April-June quarter, the highest number of cases were reported in 2019, and mortality was 7.1% across 5 years, with the highest percentage of deaths being in PPD cases and in individuals aged 20-59 years.