European Journal of Cardiovascular Medicine

Poisoning is a major public health problem, particularly in developing countries, where it remains a common mode of deliberate self-harm.¹ Among the various toxic agents, organophosphate compounds (OPCs), widely used as agricultural pesticides, are a leading cause of poisoning-related morbidity and mortality worldwide.² The World Health Organization estimates that nearly three million cases of pesticide poisoning occur annually, with organophosphates contributing to almost half of these cases.² In India, widespread agricultural use, easy availability, unsafe storage practices, and psychosocial stressors have resulted in a disproportionately high burden of OPC poisoning, with reported mortality rates ranging from 20% to 70%, far exceeding those in developed countries.^3,4

Organophosphates produce toxicity by irreversibly inhibiting acetylcholinesterase, leading to accumulation of acetylcholine at synapses and neuromuscular junctions and consequent overstimulation of muscarinic and nicotinic receptors.⁵ Clinically, this manifests as an acute cholinergic phase followed by intermediate syndrome and delayed neuropathy in some patients.⁶ Early recognition of severity is essential, as prognosis largely depends on prompt diagnosis and initiation of appropriate therapy.⁷

The Peradeniya Organophosphorus Poisoning Scale (POPS) is a validated bedside clinical tool that assesses severity based on parameters such as pulse rate, respiratory rate, pupil size, fasciculations, level of consciousness, and seizures.⁸ POPS has been shown to reliably predict morbidity and mortality; however, combining clinical scoring with biochemical markers may further improve early risk stratification.⁹

While red blood cell cholinesterase activity is considered the biochemical gold standard for assessing OPC poisoning severity, its high cost and limited availability restrict its routine use in resource-limited settings. Serum amylase has emerged as a useful surrogate marker, as cholinergic overstimulation can lead to pancreatic enzyme hypersecretion and pancreatitis, particularly in severe poisoning. Several studies have demonstrated that elevated serum amylase correlates with increased severity, respiratory failure, and mortality.¹⁰

Creatine phosphokinase (CPK) is another important biomarker reflecting skeletal muscle injury caused by persistent fasciculations, neuromuscular dysfunction, and hypoxia in OPC poisoning.¹¹ Raised CPK levels have been associated with severe poisoning, rhabdomyolysis, and poor outcomes, although interpretation must consider other potential causes of muscle injury.¹²

Despite encouraging evidence, the prognostic roles of serum CPK and amylase are not yet universally established, and further studies are required to validate their utility in conjunction with clinical scoring systems.¹³ The present study was therefore undertaken to evaluate the correlation of serum CPK and serum amylase levels with severity and clinical outcomes in patients with organophosphate poisoning.

This was a prospective observational hospital-based study was conducted on patients admitted to medicine wards and ICUs with organophosphorus compound (OPC) poisoning were enrolled after informed consent at at Fortis Escorts Hospital, Jaipur, from January 2023 to Dec 2023. The study continued until the required sample size of 100 was achieved, following ethical clearance.

Inclusion criteria: Patients aged more than 18 years with a history of organophosphorus compound (OPC) ingestion confirmed by patient history, circumstantial evidence, and compatible clinical findings, who provided written informed consent, were included in the study.

Exclusion criteria: Patients with pre-existing conditions or factors that could influence serum CPK or amylase levels were excluded. These included known myopathies; cardiac, renal, or autoimmune diseases; sepsis; trauma; epilepsy; pancreatitis; malignancies; HIV infection; patients revived following cardiopulmonary resuscitation; those who had received recent intramuscular injections; and individuals with a history of steroid, fibrate, or statin use within the preceding three months

Following initial resuscitation and gastric lavage, detailed demographic data and poisoning-related information, including the type and estimated dose of poison ingested and the lag time between ingestion and hospital presentation, were recorded. A thorough clinical examination was performed, and the severity of poisoning was assessed using the Peradeniya Organophosphorus Poisoning (POP) scale, categorizing patients as having mild (score 0–3), moderate (score 4–7), or severe poisoning (score 8–11). All patients underwent routine laboratory and radiological evaluations, including complete blood count, renal and liver function tests, cardiac biomarkers (Troponin T and CK-MB), chest X-ray, and electrocardiography. Serum creatine phosphokinase (CPK) and serum amylase levels were specifically measured on day 1 and day 3 of admission to assess their association with severity and clinical outcomes. Data were coded in MS Excel, analyzed using SPSS 16.0 to assess correlation between CPK, amylase, severity, and outcomes.

In 100 OP poisoning patients (mean age 30.77 ± 11.05 years), 40% were aged 21–30, 70% were male, 90% suicidal, 44% farmers, and 60% rural. Alcohol use was reported in 64% and smoking in 70%. Common symptoms were nausea/vomiting (51%), lacrimation (50%), and cramps (55%). Most (71%) were hospitalized within 1.1–6 h (mean 3.1 ± 2.41 h). Hospital stay: mild 3.2 d, moderate 7.8 d, severe 13 d (p<0.0001).

Table 1: Distribution of Patients According to severity of poisoning by Peradeniya Organophosphorus Poisoning (POP) Score

The table 1 shows the distribution of patients according to severity by POP scores, with 55% patients in mild, 36% patients in moderate, and 9% patients in severe category.

Figure 2: Comparison of Mean Serum Amylase Levels on Day 1 & 3 According to POP Score.

The table demonstrates a strong association between POP score severity and patient outcomes. All patients with a mild POP score were discharged successfully, with no recorded deaths (100%). Among patients with a moderate POP score, the majority were discharged (97.22%), while a small proportion succumbed to the illness (2.78%). In contrast, outcomes were markedly poorer in patients with a severe POP score, where only 22.22% were discharged and a high mortality rate of 77.78% was observed. The difference in outcomes across the three POP score categories was statistically highly significant (p < 0.0001), indicating that increasing POP score severity is strongly predictive of adverse outcomes.

Figure 3: Duration of Hospital Stay According to POP Score

In figure 3, All patients with mild POP scores (100%) had a hospital stay of less than 7 days, with a mean stay of 3.3 ± 0.85 days. Among moderate cases, 88.89% stayed between 7 to 14 days, and 11.11% stayed less than 7 days, with a mean stay of 7.88 ± 1.80 days. In the severe group, 33.33% stayed between 7 to 14 days, and 66.66% stayed longer than 14 days, resulting in a mean stay of 14 ± 3.46 days. The differences in hospital stay duration among the groups were statistically significant (p < 0.0001).

Figure 4: Comparison of Mean CPK Levels on Day 1 and Day 3 Between Discharged and Deceased Patients.

The table compares mean CPK levels between patients who died and those who were discharged at day 1 and day 3. At day 1, mean CPK levels were markedly higher among patients who died (1141.67 ± 3611.29) compared to those who were discharged (301.77 ± 281.08), and this difference was statistically highly significant (p < 0.0001). A similar trend was observed at day 3, where mean CPK levels further increased in the death group (2360.07 ± 1171.01) while remaining relatively low in the discharge group (227.64 ± 150.39). This difference was also statistically highly significant (p < 0.0001). These findings indicate that elevated and rising CPK levels are strongly associated with mortality.

Figure 5: Comparison of Mean Serum Amylase Levels on Day 1 and Day 3 Between Discharged and Deceased Patients

The table shows a comparison of mean serum amylase levels between patients who died and those who were discharged at day 1 and day 3. At day 1, mean amylase levels were significantly higher in patients who died (276.51 ± 57.15) compared to those who were discharged (142.93 ± 87.26), with the difference being statistically highly significant (p < 0.0001). This difference became more pronounced by day 3, as mean amylase levels remained elevated in the death group (280.45 ± 81.41) while showing a further decline in the discharge group (113.97 ± 44.51). The association between elevated amylase levels and mortality at both time points was statistically highly significant (p < 0.0001), suggesting that persistently raised amylase levels are linked to poor clinical outcomes.

The ROC analysis assesses the accuracy of CPK and amylase levels in predicting patient outcomes. CPK levels on day 1 had an AUC of 0.959 (p < 0.0001) with 100% sensitivity and 93.5% specificity at a cutoff of 550.7. On day 3, CPK showed even higher accuracy with an AUC of 0.989 (p < 0.0001), 100% sensitivity, and 95.7% specificity at a cutoff of 481.5. Amylase levels also demonstrated strong predictive ability, with day 1 showing an AUC of 0.931 (p < 0.0001), 100% sensitivity, and 88% specificity at a cutoff of 207.5. On day 3, amylase had an AUC of 0.967 (p < 0.0001), 100% sensitivity, and 87% specificity at a cutoff of 162.

Figure 6: ROC Analysis of CPK Levels on Day 1 and Day 3 for Predicting Patient Outcome.

Figure 7: ROC Analysis of CPK and Serum Amylase Levels on Day 1 and Day 3 for Predicting Patient Outcome.

ROC analysis showed CPK on day 1 had moderate accuracy (AUC = 0.70, p < 0.001) at 125.3 IU/L with 80.9% sensitivity, 43.4% specificity. Day 3 CPK was excellent (AUC = 0.99, p < 0.00001) at 498 IU/L with 100% sensitivity, 97.9% specificity. Amylase on days 1 (251.5 IU/L) and 3 (195.8 IU/L) had AUC = 0.99 (p < 0.0001), 100% sensitivity, >95% specificity.

Acute organophosphorus (OP) poisoning remains a major public health problem in developing countries and continues to pose significant diagnostic and therapeutic challenges due to its potential for rapid deterioration and high mortality. Early assessment of severity using validated clinical scoring systems and reliable biochemical markers is therefore essential. The present study evaluated the usefulness of the Peradeniya Organophosphorus Poisoning (POP) score in conjunction with serum creatine phosphokinase (CPK) and serum amylase levels for predicting severity and clinical outcomes.

In the present study, OP poisoning predominantly affected young adults with a mean age of 30.77 ± 11.05 years, with males, rural residents, farmers, and suicidal ingestion forming the majority. Similar demographic patterns have been reported by Bharathisezhian A et al.14, Kumari VS et al.15, and Rayannavar N et al.16, who also observed a higher incidence among young, economically productive males from rural backgrounds. This distribution reflects occupational exposure, easy accessibility to organophosphates, and psychosocial stressors in this population.

Severity assessment using the POP score revealed that most patients had mild poisoning (55%), followed by moderate (36%) and severe (9%) cases, findings comparable to those of Paul G et al.17, Thirunavukkarasu S et al.18, and Dubey TN et al.19 A strong correlation was observed between POP score severity and clinical outcomes in the present study, with 100% survival in mild cases and a mortality of 77.78% in severe cases (p < 0.0001). Similar trends were reported by Reddy GRK et al.20 and Kumar A et al.,21 who demonstrated increasing mortality with higher POP scores, reinforcing the prognostic value of this clinical scale.

Serum CPK levels showed a significant rise with increasing POP severity and were markedly higher in deceased patients. These findings are in agreement with studies by Minz NT et al.22, Mural R et al.23, and Dubey TN et al.19, all of whom reported a positive correlation between elevated CPK levels and poisoning severity as well as poor outcomes. Elevated CPK likely reflects sustained muscle injury due to prolonged fasciculations, neuromuscular junction dysfunction, and hypoxia.

Similarly, serum amylase levels were significantly higher in severe poisoning and among non-survivors. Thirunavukkarasu S et al.18, Minz NT et al.22, and Raveendra KR et al.24 also demonstrated a proportional rise in amylase levels with increasing severity and mortality, attributing this to cholinergic overstimulation of pancreatic exocrine secretion. The ROC analysis in the present study further confirmed the excellent predictive accuracy of both CPK and amylase, particularly on day 3, findings comparable to those reported by Mural R et al.23 and Hassan NAM et al.25

Overall, the present study, in concordance with existing literature, highlights that POP scoring combined with serial serum CPK and amylase estimation offers a simple, inexpensive, and reliable method for early risk stratification and outcome prediction in acute OP poisoning, particularly in resource-limited settings.

This study highlights the clinical utility of serum CPK and serum amylase as reliable biochemical indicators for evaluating disease severity and predicting outcomes in organophosphorus poisoning. The majority of affected patients were young adult males, predominantly from rural backgrounds, with suicidal ingestion being the most common mode of exposure. Higher levels of CPK and amylase showed a strong positive correlation with increasing POP scores, greater clinical severity, prolonged hospital stay, and increased mortality. Furthermore, ROC analysis demonstrated excellent predictive accuracy of these markers, particularly by day 3 of admission, reinforcing their value in early risk stratification and in guiding timely and appropriate management of patients with organophosphorus toxicity.

1. Karalliedde L, Feldman R, Henry J, Marrs T. Organophosphates and health. Singapore: World Scientific; 2001. p. 213–4.
2. Eddleston M, Chowdhury FR. Pharmacological treatment of organophosphorus insecticide poisoning: the old and the possible new. Br J Clin Pharmacol. 2016;81:462–70.
3. Gururaj G, Isaac MK. Epidemiology of suicides in Bangalore. Bangalore: National Institute of Mental Health & Neuro Sciences; 2001. p. 130.
4. Pillay V, editor. Organophosphate/carbamate pesticide poisoning – a primer for physicians. 3rd Annual Conference of Indian Society of Toxicology (Toxocon-3); 2007. p. 218–9.
5. Dubey TN, Yadav S, Kawre KK. Correlation of severity of organophosphorus poisoning as assessed by Peradeniya organophosphorus poisoning scale with serum amylase and CPK level. Int J Contemp Med Res. 2016;3:2534–7.
6. Ahmed SM, Das B, Nadeem A, Samal RK. Survival pattern in patients with acute organophosphate poisoning on mechanical ventilation: A retrospective intensive care unit based study in a tertiary care teaching hospital. Indian J Anaesth. 2014;58:11–7.
7. Chaudhary R, Bhandari R, Malla G, Poudel M, Lamsal M. Correlation of clinical score and serum acetylcholinesterase in emergency ward of a tertiary hospital. J BP Koirala Inst Health Sci. 2019;2:19–27.
8. Senanayake N, de Silva HJ, Karalliedde L. A scale to assess severity in organophosphorus intoxication: POP scale. Hum Exp Toxicol. 1993;12:297–9.
9. Vernekar PV, Shivraj K. Peradeniya organophosphorus poisoning scale (POP) as a predictor of respiratory failure and mortality in organophosphorus poisoning. Sch J Appl Med Sci. 2017;5:1841–4.
10. Lee WC, Yang CC, Deng JF, Wu ML, Ger J, Lin HC, et al. The clinical significance of hyperamylasemia in organophosphate poisoning. J Toxicol Clin Toxicol. 1998;36(7):673–81.
11. Patel M, et al. Role of serum amylase in organophosphorus poisoning: A diagnostic tool. Indian J Toxicol. 2014;15(4):134–7.
12. Singh A, Garg P. Diagnostic significance of amylase in organophosphorus poisoning. Toxicol Rep. 2012;19(3):221–5.
13. Hassan NA, Madboly AG. Correlation between serum creatine phosphokinase and severity of acute organophosphorus poisoning: A prospective clinical study (2012–2013). IOSR J Environ Sci Toxicol Food Technol. 2013;4(5):18–29.
14. Bharathisezhian A, Kalaisezhian N, Kumarraja M, Yoganandh T. A study of the prognostic significance of serum creatine phosphokinase level in organophosphorus compound poisoning patients. Int J Acad Med Pharm. 2023;5(2):453–7.
15. Kumari SV, Syed IBK, Shaik YA. Study of prognostic significance of serum levels of creatine kinase in OPP: Importance of elevated serum amylase in patients of organophosphorus compound poisoning. Int J Pharm Clin Res. 2024;16(10):1322–9.
16. Rayannavar N, Deokar VV, Desai J, Reddy S, Bhaleghare S. Study of serum creatine phosphokinase (CPK) as a prognostic indicator in patients with organophosphorus compound poisoning. Int J Health Sci (IJHS). 2022;6:2962–82.
17. Paul G, Kabir MR, Hasan AK, Ahammed SK, Hossain ME, Ahammed F, et al. Correlation of serum amylase level with the severity of acute organophosphorus compounds poisoning. Int J Adv Med. 2021;8:352–6.
18. Thirunavukkarasu S, Radhakrishnan S, Shankar R. Serum amylase: a prognostic indicator in acute organophosphorous compound poisoning. Int J Health Sci. 2022;6(S8):5028–35.
19. Dubey TN, Yadav S, Kawre KK. Correlation of severity of organophosphorus poisoning as assessed by Peradeniya organophosphorus poisoning scale with serum amylase and CPK level. Int J Contemp Med Res. 2016;3:2534–7.
20. Reddy GRK. Peradeniya Organophosphorous Scale (POP) as a predictor of mortality in organophosphorous poisoning. 2020.
21. Kumar A, Mudiyammanavara RN, Ravikiran R. Correlation between serum amylase, serum creatine phosphokinase (CPK), random blood sugars (RBS), serum cholinesterase with outcome: Acute organophosphorus compound poisoning. Int J Life Sci Biotechnol Pharm Res. 2023;12(2):1747–51.
22. Minz NT, Singh SC, Jena P, Patro PK. Correlation of serum amylase, lipase and creatine kinase with severity of organophosphate poisoning. J Clin Diagn Res. 2021;15(7):OC19–21.
23. Mural R, Bajaj G, Mammen D. Study of level of total creatine phosphokinase as prognostic indicator in acute organophosphorus poisoning: A prospective study. Int J Contemp Med Res. 2017;4(2):77–83.
24. Raveendra KR, Mohan CN. A study of serum amylase as a probable prognostic marker in acute organophosphorus poisoning. APIK J Int Med. 2021;9:94–8.
25. Hassan NA, Madboly AG. Correlation between serum creatine phosphokinase and severity of acute organophosphorus poisoning: A prospective clinical study (2012–2013). IOSR J Environ Sci Toxicol Food Technol. 2013;4(5):18–29.