Organophosphorus (OP) poisoning remains a global public health concern, contributing significantly to morbidity and mortality, particularly in agricultural regions where these compounds are heavily used as pesticides. Countries like India, where farming is a primary economic activity, face a disproportionate burden of OP poisoning cases.1,2

According to the World Health Organization, around 250,000 deaths occur annually due to various forms of poisoning, with organophosphates accounting for about 150,000 fatalities.3 these chemicals inhibit acetylcholinesterase, accumulating acetylcholine and subsequent overstimulation of the nervous system, which manifests in a wide range of clinical symptoms, from mild cholinergic signs to life-threatening complications such as respiratory failure.4

Biochemical analysis plays a crucial role in diagnosing and managing OP poisoning. Commonly assessed markers include serum amylase, lipase, lactate dehydrogenase (LDH), creatine phosphokinase (CPK), and immunoglobulins.5 Among these, serum amylase has drawn attention for its potential association with OP poisoning severity. Preliminary studies suggest that elevated serum amylase levels may indicate pancreatic involvement, which can be asymptomatic but carry the risk of complications like shock.6

Serum amylase, primarily known for its role in diagnosing pancreatic disorders, has emerged as a candidate marker in OP poisoning. Elevated amylase levels in patients exposed to organophosphates may reflect autonomic stimulation and the exocrine effects of parasympathetic overactivity.7,8 Despite its potential as a marker for toxicity, the exact relationship between serum amylase levels and the clinical outcomes of OP poisoning remains inadequately explored. Establishing a clear correlation between serum amylase and the severity of poisoning could provide a valuable tool for clinicians, particularly in regions where advanced diagnostic facilities are unavailable.9,10

Understanding the role of serum amylase in OP poisoning could enhance patient care by refining prognostic assessments and guiding treatment decisions, ultimately contributing to more effective public health strategies and clinical interventions in managing OP poisoning cases. This study aims to investigate the correlation between serum amylase levels and clinical outcomes in patients with acute OP poisoning.

Study Setting, Study Type, and Study Duration

This prospective observational study was conducted at GMERS Medical College, Gandhinagar, within the Department of General Medicine. The total study duration was from November 2020 to December 2021. The initial concept note preparation occurred between November 2020 and December 2020, while data collection occurred from December 2020 to December 2021.

Study Participants

The study participants consisted of patients admitted with acute organophosphorus (OP) poisoning to the emergency room, wards, and ICU of the General Medicine Department at GMERS Medical College, Gandhinagar. The study included both male and female patients aged 18 years and above with a confirmed history of OP poisoning. Participants were selected based on specific inclusion and exclusion criteria. The inclusion criteria included all patients with a history of OP poisoning exposure. Patients were excluded if they had a poisoning history exceeding 48 hours, had consumed OP poison mixed with other substances, or had a history of chronic alcoholism, tobacco use, chronic renal or hepatic disorders, or gallstone disease. Other exclusion factors included pregnancy, a history of abdominal trauma, endoscopic retrograde cholangiopancreatography (ERCP), pancreatitis, or the use of drugs known to induce pancreatitis, such as Azathioprine, Thiazides, and Steroids. Patients without informed consent were also excluded from the study.

Sample Size and Sampling Technique

The sample size was determined using a prevalence-based calculation from prior poisoning data at GMERS Medical College, which indicated that 28.20% of the total poisoning patients (n=351) were due to OP poisoning. Using a 95% confidence level and a 5% allowable error, the sample size was calculated to be 81 patients. A total of 83 patients were included in the study based on the cases presented during the data collection period.

Measurements

Serum amylase levels were measured to assess their correlation with clinical severity and outcomes in acute organophosphorus poisoning. Blood samples (2 ml) were collected from each patient under aseptic conditions at three specific time points: on admission, day 1, and day 3. The samples were collected in plain tubes, allowed to clot, and then centrifuged to separate the serum for analysis. Serum amylase was measured spectrophotometrically at 404 nm, with the normal reference range being 20-115 IU/L. In addition to serum amylase, serum lipase and serum cholinesterase levels were also measured. Serum lipase was assessed spectrophotometrically at 548 nm, with a 13-60 IU/L reference range. Serum cholinesterase levels were measured at 405 nm, with normal values ranging from 5000-11500 U/L. These biochemical measurements were performed using standard laboratory protocols to ensure accuracy and consistency in the data.

Data Collection

Data collection for the study involved a systematic process beginning with the admission of patients diagnosed with acute organophosphorus poisoning. After obtaining informed consent from the patient's relatives, detailed demographic information, clinical history, and comorbidities were recorded using a structured proforma. Blood samples (2 ml) were drawn under aseptic conditions on admission, days 1 and 3. These samples were processed to extract serum for biochemical analysis, including measurements of serum amylase, serum lipase, and serum cholinesterase using spectrophotometric methods. Clinical assessments of symptoms such as respiratory distress, muscle weakness, and cholinergic signs were documented, alongside treatment details such as administering atropine and pralidoxime. All collected data were securely stored and prepared for statistical analysis to evaluate the correlation between serum amylase levels, clinical severity, and patient outcomes.

Ethical Issues

Ethical clearance was obtained from the institutional ethics committee. Written informed consent was obtained from participants' relatives, and no patient was denied standard treatment regardless of participation.

Statistical Analysis

Data were entered into Excel and analyzed using Epi info CDC 7. Descriptive statistics were calculated as means and standard deviations for quantitative data and frequencies and proportions for qualitative data. Associations between variables were tested using Chi-square for qualitative data and ANOVA for quantitative comparisons involving more than two groups. A p-value of less than 0.05 was considered statistically significant.

In this study, 38.6% of patients had serum amylase levels greater than 115 IU/L, while 61.4% had levels below this threshold. As shown in Table 1, most patients (60.2%) were in the 18-30 age group, with no significant correlation between age and serum amylase levels (p = 0.538). Males constituted 61.4% of the study population, but no significant association was found between gender and serum amylase levels (p = 0.279). Most patients (95.2%) presented with suicidal poisoning, and oral ingestion was the primary mode of exposure (98.8%). Chlorpyrifos was the most common compound involved, with 50.6% of the patients exposed, although no significant correlation was observed between compound exposure and serum amylase levels (p = 0.403).

Table 1: Sociodemographic and Exposure-Related Correlation with Serum Amylase

According to Table 2, 40.6% of patients with serum amylase levels greater than 115 IU/L experienced dyspnea and cough, compared to 15.7% of those with lower serum amylase levels, showing a significant correlation (p = 0.01). Other clinical features, such as salivation (45.8%), nausea, vomiting, diarrhoea (85.5%), and sweating

(38.6%), did not show a significant association with serum amylase levels (p > 0.05). Muscle weakness and restlessness were present in 12% and 15.7% of the patients, respectively, but no significant differences were found between groups. Similarly, 21.7% of patients had headaches, with no correlation with serum amylase levels (p = 0.26).

Table 2: Correlation between Clinical Features and Serum Amylase

 Patients with elevated serum amylase levels were significantly more likely to have pinpoint pupils (31.2% vs. 5.9%, p = 0.007). Constricted pupils were common but not linked considerably to amylase levels. (Table 3) as per Table 4, Patients with elevated serum amylase levels had a significantly higher mortality rate (37.5%) than those with normal levels (3.9%, p = 0.000), while survival was more common in patients with lower serum amylase.

Table 3: Correlation between Pupil Size and Serum Amylase

Table 4: Correlation between Clinical Outcome and Serum Amylase Levels

Organophosphates (OP) and carbamates are widely used pesticides that can cause life-threatening intoxication, particularly in developing countries where fatal poisoning is more common among farm workers. Acute OP poisoning often presents as a medical emergency, requiring close monitoring, and management is based on clinical severity assessed through both clinical signs and laboratory markers, including serum amylase levels, which are considered an important indicator of severity in OP poisoning.11,12

In this study, 95.2% of the poisoning cases were suicidal in nature, which aligns with findings from other studies, such as those by Devi TJ et al.13 (100%) and Biwas PK et al.14 (96%). Nearly all patients (98.8%) had oral exposure to the poison. The commonality of suicidal intent reflects the widespread use of OP compounds in self-harm, a trend seen in developing regions where access to these toxic substances is relatively easy.

The most frequently used poison in this study was chlorpyrifos (50.6%), a finding similar to the survey by Bhattacharyya K et al.,15 though  Devi TJ et al.13 found methyl parathion to be the most common. No significant association was found between the type of compound used and serum amylase levels, indicating that the compound itself may not directly affect enzyme elevation.

The most affected age group in this study was 18-30 years (60.2%), consistent with Koirala M et al.17 (44.74% in the 15-24 age group) and Moussa ME et al.17 (44.5% in the 18-40 group). This age group is particularly vulnerable due to psychosocial stressors such as academic pressure, relationship issues, and family conflicts, which can contribute to suicidal tendencies.

In this study, males comprised 61.4% of the cases, a similar pattern also observed in previous studies13,18,19 (all reporting around 70% male). However, studies by Biwas PK et al.14 and Moussa ME et al.17 noted a higher incidence among females, highlighting that gender distribution may vary based on regional and cultural factors.

Salivation, sweating, nausea, vomiting, and diarrhoea were the most common symptoms. A significant association was found between elevated serum amylase and dyspnea and cough, with 40.6% of patients with raised amylase levels exhibiting these symptoms. Pinpoint pupils were noted in 31.2% of patients with raised serum amylase, indicating a strong correlation between enzyme levels and this clinical sign. However, no significant relationship was found between heart rate or systolic blood pressure and serum amylase levels, possibly due to early intervention at primary care centres.

Among the patients with raised serum amylase, 81.6% had severe poisoning, and the inverse relationship between serum cholinesterase and amylase was significant, consistent with findings by Choperla SK et al..20 This suggests that as cholinesterase levels drop, amylase levels rise, reflecting the severity of poisoning.

26.5% of patients required ventilatory support, and 56.3% with elevated serum amylase needed mechanical ventilation. This finding is supported by Biwas PK et al.14 and Goel A et al.,21 who also found that patients with higher serum amylase levels were more likely to require ventilatory assistance, indicating the role of amylase as a marker of respiratory compromise in severe OP poisoning.

The overall mortality rate in this study was 16.8%, similar to other studies such as Devi TJ et al.13 (10%) and Moussa ME et al.17 (10%). Among those with elevated serum amylase, 37.5% died, compared to only 3.9% in those with normal levels. This significant relationship between serum amylase and mortality suggests that elevated amylase may be a strong predictor of poor outcomes in OP poisoning, consistent with findings by Biwas PK et al.14 and Moussa et al.,17 where hyperamylasemia was strongly associated with mortality.

In summary, elevated serum amylase in organophosphate poisoning correlates with increased severity, need for ventilatory support, and higher mortality, making it a critical marker in assessing patient outcomes.

Based on the findings of this study, elevated serum amylase levels in patients with acute organophosphate poisoning are strongly associated with greater clinical severity, the need for ventilatory support, and higher mortality rates. Patients with raised amylase levels were more likely to present with significant symptoms such as dyspnea, cough, and pinpoint pupils, and these patients had a substantially higher risk of death compared to those with normal amylase levels. The inverse correlation between serum cholinesterase and amylase levels further underscores the utility of serum amylase as a reliable marker of poisoning severity. Given these findings, serum amylase should be considered a valuable prognostic tool in managing organophosphate poisoning, aiding in the early identification of high-risk patients and guiding clinical interventions to improve outcomes.

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