European Journal of Cardiovascular Medicine

(OP) compounds are widely used as agricultural pesticides, particularly in developing countries, making them a common cause of acute poisoning. According to the World Health Organization, pesticide poisoning contributes substantially to global morbidity and mortality, with OP compounds accounting for a significant proportion of cases, especially in South and Southeast Asia.¹ In India, OP poisoning is frequently encountered in emergency departments due to occupational exposure, accidental ingestion, and deliberate self-harm.²

OP compounds exert their toxic effects primarily by irreversible inhibition of acetylcholinesterase, resulting in accumulation of acetylcholine at synapses and neuromuscular junctions. This leads to overstimulation of muscarinic, nicotinic, and central nervous system receptors, producing the classical cholinergic toxidrome.³ Severe poisoning can result in respiratory failure, cardiac arrhythmias, seizures, prolonged hospitalization, and death.⁴

Despite advances in management, including atropine, oximes, and ventilatory support, mortality remains high in severe cases.⁵ Early risk stratification is therefore essential for triage, early airway management, and intensive care admission. Clinical scoring systems provide objective and reproducible tools to assess severity at presentation.

The Poison Severity Score (PSS), developed by the International Programme on Chemical Safety, grades poisoning severity based on clinical manifestations.⁶ The Glasgow Coma Scale (GCS) is a simple neurological assessment tool that reflects central nervous system involvement and has been shown to correlate with outcomes in OP poisoning.⁷ In addition, serum cholinesterase levels serve as a biochemical marker of OP toxicity and may have prognostic value.

This study aims to evaluate the role of PSS, GCS, and serum cholinesterase levels in predicting clinically relevant outcomes in patients with organophosphorus poisoning.

This was a prospective observational study conducted in the Department of Emergency Medicine at Subbaiah Institute of Medical Sciences and Research Centre, Shivamogga over a period of 1 year. Sample Size A total of 100 patients with organophosphorus poisoning were included. Inclusion Criteria • Age ≥18 years • History of ingestion or exposure to organophosphorus compounds • Clinical features consistent with OP poisoning • Admission within 24 hours of exposure Exclusion Criteria • Mixed or unknown poisoning • Chronic OP exposure • Pre-existing neurological disorders • Alcohol or sedative co-ingestion • Pregnant women Data Collection Demographic and clinical details were recorded at admission, including age, sex, mode of exposure, time to presentation, and vital parameters. Scoring Systems and Laboratory Assessment at Admission The following tools were applied at the time of admission to stratify patient risk: • Poison Severity Score (PSS): The Poison Severity Score (PSS) was used to grade the clinical severity of poisoning as per World Health Organization–International Programme on Chemical Safety (WHO-IPCS) guidelines.8 It was assessed by evaluating multisystem involvement (muscarinic, nicotinic, and CNS features) and categorized as: o Grade 1 (Minor): Mild, transient, and self-limiting symptoms. o Grade 2 (Moderate): Pronounced or prolonged symptoms. o Grade 3 (Severe): Severe or life-threatening symptoms. o Grade 4 (Fatal): Death. • Glasgow Coma Scale (GCS): Neurological status at admission was assessed using the Glasgow Coma Scale (GCS) as originally described by Teasdale and Jennett, evaluating three standard components: eye opening, verbal response, and motor response.9 Patients were grouped based on their total score: o Mild: 13–15. o Moderate: 9–12. o Severe: ≤8. • Serum Cholinesterase: Levels were measured at admission and categorized as >4000 U/L, 2000–4000 U/L, 1000–2000 U/L, and <1000 U/L to correlate biochemical inhibition with clinical outcomes. All patients were managed according to standard institutional protocols for organophosphorous poisoning. Outcome Measures Patients were followed until discharge or death. The outcomes assessed were: • Need for mechanical ventilation(respiratory failure, GCS</=8 or airway compromise) • Length of hospital stay • Mortality Statistical Analysis Data were analyzed using SPSS version 26. Categorical variables were expressed as frequencies and percentages, and continuous variables as mean ± SD. Associations were assessed using Chi-square test and ANOVA/Kruskal Willis test as appropriate. Normality of continuous variables was assessed before applying parametric tests. A p-value <0.05 was considered statistically significant.

Table 1. Demographic Characteristics of Study Population (n = 100)

The study population predominantly consisted of young adult males, with suicidal ingestion being the most common mode of exposure.(Table 1)

Table 2. Distribution of Poison Severity Score (PSS)

Most patients presented with moderate to severe poisoning.(Table 2)

Table 3. Distribution of Glasgow Coma Scale (GCS)

One-fifth of patients had severe impairment of consciousness at presentation. (Table 3)

Table 4. Distribution of Serum Cholinesterase Levels

One fifth of the patients had significant reduction in serum cholinesterase levels on arrival. (Table 4)

Table 5. GCS vs Clinical Outcomes

Lower GCS scores were associated with significantly higher ventilatory requirement, longer hospital stay, and increased mortality. (Table 5)

Table 6. PSS vs Clinical Outcomes

Increasing PSS grades showed a strong and statistically significant association with adverse clinical outcomes particularly ventilatory requirement, prolonged hospital stay, and mortality, with fatal outcomes confined to higher severity grades. (Table 6)

Table 7. Serum Cholinesterase vs Clinical Outcomes

Lower serum cholinesterase levels were significantly associated with increased need for mechanical ventilation, prolonged hospitalization, and higher mortality. (Table 7)

Overall ventilation requirement was 41%, length of hospital stay was 8.4 ± 4.2 days and the mortality was 13%. 

Organophosphorus poisoning continues to be a significant cause of morbidity and mortality in developing countries, particularly in agricultural regions where these compounds are easily accessible. Early identification of patients at risk for adverse outcomes is essential to guide timely airway management, intensive care admission, and optimal resource utilization. This study evaluated the prognostic value of Poison Severity Score (PSS), Glasgow Coma Scale (GCS), and serum cholinesterase levels in predicting clinically relevant outcomes in patients with organophosphorus poisoning.

The demographic profile observed in the present study, with a predominance of young adult males and suicidal exposure as the most common mode of poisoning, is consistent with findings from previous Indian and international studies.¹⁰,¹¹ This reflects underlying socioeconomic stressors and easy availability of agricultural pesticides in rural settings.

The Poison Severity Score demonstrated a strong and statistically significant association with all measured clinical outcomes. Increasing PSS grades were associated with higher requirement for mechanical ventilation, prolonged hospital stay, and increased mortality. Patients classified as PSS Grade 3 had markedly higher rates of ventilatory support and death and Grade 4 had been classified as Dead on arrival, highlighting the utility of PSS as a comprehensive tool for prognosticating the OP poisoning patients. These findings are comparable to studies by Bilgin et al. and Davies et al., which reported that higher PSS grades correlate with greater severity and poorer outcomes in OP poisoning.¹²,¹³ The strength of PSS lies in its ability to capture multisystem involvement, making it particularly useful in the emergency setting.

Glasgow Coma Scale also showed a strong correlation with outcomes in this study. Patients with GCS ≤8 at admission had significantly higher ventilatory requirements, longer hospital stay, and the highest mortality rate. Depressed consciousness in OP poisoning reflects severe central nervous system involvement, hypoxia, and impending respiratory failure. Similar observations have been reported by Goswamy et al. and Rehiman et al., who identified low GCS as a powerful predictor of mortality in OP poisoning.¹⁴,¹⁵ The simplicity and rapid bedside applicability of GCS make it an invaluable tool for early risk stratification.

Serum cholinesterase levels, a biochemical marker of organophosphorus toxicity, showed a clear inverse relationship with clinical outcomes. Patients with serum cholinesterase levels below 1000 U/L had significantly higher rates of mechanical ventilation, prolonged hospitalization, and mortality compared to those with higher levels. This finding reinforces the role of serum cholinesterase as an objective indicator of poisoning severity. Several studies have demonstrated that lower cholinesterase levels are associated with increased neuromuscular dysfunction, respiratory failure, and poor outcomes.⁶,⁷ The present study supports these observations and highlights the added prognostic value of serum cholinesterase when used alongside clinical scoring systems.

On descriptive comparision, PSS provided a broader assessment of overall clinical severity and was particularly effective in predicting ventilatory requirement and prolonged hospital stay. GCS was a strong predictor of mortality, reflecting the impact of central nervous system involvement on survival. Serum cholinesterase complemented both clinical scores by offering an objective biochemical measure of toxicity severity. The combined assessment using PSS, GCS, and serum cholinesterase allowed more accurate identification of high-risk patients at an early stage.

Early application of these tools in the emergency department can facilitate prompt airway protection, early intensive care referral, and aggressive management, which are crucial determinants of outcome in OP poisoning. Given their simplicity, cost-effectiveness, and widespread availability, these parameters are particularly valuable in resource-limited settings where advanced monitoring may not be readily accessible.

Poison Severity Score, Glasgow Coma Scale, and serum cholinesterase levels assessed at admission are strong predictors of need for mechanical ventilation, length of hospital stay, and mortality in organophosphorus poisoning. Their combined use allows early identification of high-risk patients and supports timely and appropriate clinical decision-making.

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