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Table of Contents
ORIGINAL ARTICLE
Year : 2019  |  Volume : 7  |  Issue : 4  |  Page : 109-116

Association between serum cholinesterase levels and clinical outcome in patients of organophosphorus compound poisoning – One-year hospital-based longitudinal study


Department of General Medicine, J. N. Medical College, Belagavi, Karnataka, India

Date of Submission04-Sep-2019
Date of Acceptance19-Sep-2019
Date of Web Publication18-Oct-2019

Correspondence Address:
Dr. Vivek Veereshkumar Shirol
B – 7/1, Staff Quarters, JNMC Campus, Nehru Nagar, Belagavi - 590 010, Karnataka
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/AJIM.AJIM_46_19

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  Abstract 


Background and Objectives: The activity of serum cholinesterase (SChE) decreases in organophosphate compound poisoning. This study was aimed to evaluate SChE levels as a prognostic marker for patients with organophosphorus (OP) poisoning. Materials and Methods: The present 1-year hospital-based longitudinal study was done on a total of 85 patients admitted with OP compound poisoning in the Department of Medicine, Hospital and Medical Research Centre, from January 2014 to December 2014. The estimation of pseudocholinesterase levels was done at the time of admission, on the 5th day and at the time of discharge. Results: Maximum number of cases had age <30 years (55.29%), and the mean age was 35.28 ± 15.34 years. There was male preponderance with a male to female ratio of 2.4:1. The most commonly consumed compound was malathion (24.71%). Majority of the patients (62.35%) presented after 3–6 h of consumption. The most common symptom was vomiting (87.06%), and peradeniya OP poisoning score revealed moderate intoxication in 58.82% of the patients. SChE levels were profoundly low (≤2500 U/L) in 62.35% of the patients at admission, 65.33% on 5th day, and 62.71% at the time of discharge. Acute renal failure was the most common complication, noted in 23.08% of the patients. Mortality was noted in 15.29% of the patients, and intermediate syndrome was the most common cause (30.77%). Conclusion: There is a positive association of SChE with hospital stay (1st day levels and serial estimation); requirement of ventilatory support (1st day levels); and outcome (serial estimation).

Keywords: Organophosphorus compound poisoning, peradeniya organophosphorus poisoning scale, serum cholinesterase


How to cite this article:
Kothiwale VA, Shirol VV, Yerramalla VV, Somannavar VG. Association between serum cholinesterase levels and clinical outcome in patients of organophosphorus compound poisoning – One-year hospital-based longitudinal study. APIK J Int Med 2019;7:109-16

How to cite this URL:
Kothiwale VA, Shirol VV, Yerramalla VV, Somannavar VG. Association between serum cholinesterase levels and clinical outcome in patients of organophosphorus compound poisoning – One-year hospital-based longitudinal study. APIK J Int Med [serial online] 2019 [cited 2019 Dec 6];7:109-16. Available from: http://www.ajim.in/text.asp?2019/7/4/109/269568




  Introduction Top


Organophosphorus (OP) compounds are a diverse group of chemicals used in both domestic and industrial settings. Organophosphate compounds (OPCs) are frequently used as pesticides in agricultural activities. Examples of organophosphates include insecticides (malathion, parathion, diazinon, fenthion, dichlorvos, chlorpyrifos, ethion), nerve gases (soman, sarin, tabun, VX), ophthalmic agents (echothiophate and isoflurophate), and antihelmintics (trichlorfon). Herbicides (tribufos [DEF], merphos) are tricresyl-phosphate-containing industrial chemicals.[1],[2]

Pesticide poisoning is a major public health problem in the developing nation.[3] Millions of people are exposed to the danger of hazardous occupational practices and unsafe storage of pesticides.[4] However, it is deliberate self-poisoning which causes the great majority of deaths and places immense strain on hospital services, particularly in Asia.[4],[5]

According to a World Health Organization report, three million cases of pesticide poisoning occur annually worldwide, and most of them are in Asia, of which at least half are due to OP poisoning.[6],[7]

Poisoning is a common method of suicide, especially in the developing world.[7] OP compounds are among the most common poisons used for deliberate self-poisoning in India and other parts of the world.[8],[9],[10],[11] Based on the literature from India, rate of suicidal poisoning with OP compounds ranges from 10.3% to 43.8%.[12] Among OP poisoned patients in India, hospital mortality rate is reported to be as high as 20%–70%.[12],[13]

OP compounds increase the accumulation of acetylcholine (ACh) in the synaptic gap through inhibition of acetylcholinesterase (AChE) and decrease in the degradation of ACh, thus leading to excessively increased cholinergic activity and the appearance of cholinergic symptoms. Oximes like pralidoxime (PAM) cause AChEs to reactivate by binding to OPCs that have been bound to acetylcholinesterases.[14]

The primary mechanism of action of organophosphate pesticides is inhibition of carboxyl ester hydrolases, particularly AChE. AChE is an enzyme that degrades the neurotransmitter ACh into choline and acetic acid. ACh is found in the central and peripheral nervous system, neuromuscular junctions, and red blood cells (RBCs). Organophosphates inactivate AChE by phosphorylating the serine hydroxyl group located at the active site of AChE. The phosphorylation occurs by loss of an organophosphate leaving group and establishment of a covalent bond with AChE. Once AChE has been inactivated, ACh accumulates throughout the nervous system, resulting in overstimulation of muscarinic and nicotinic receptors. Clinical effects are manifested via activation of the autonomic and central nervous systems and at nicotinic receptors on skeletal muscle.[2],[15] OPs lead to undesired effects on the central nervous system, cardiovascular system, respiratory system, urogenital system, neuromuscular junction, and metabolic and endocrine systems. Muscarinic symptoms such as miosis, bradycardia, bronchospasm, urine and fecal incontinence and nicotinic symptoms such as muscle weakness, muscle fasciculations, tachycardia, loss of consciousness, and globe vesicale occur.[2],[16]

The peradeniya OP poisoning (POP) scale assesses the severity of the poisoning based on the symptoms at presentation and is simple to use.[17]

There are various factors that predict the outcome in acute organophosphate poisoning. The recognized predictors of poor outcome include initial blood pressure, Glasgow Coma Scale score, serum cholinesterase (SChE) level, Acute Physiology and Chronic Health Evaluation II score, and electrocardiogram (ECG) findings (prolongation of QT interval).[18],[19] RBC cholinesterase (true cholinesterase) level is a sensitive indicator, but its estimation is difficult and is usually not done. SChE activity is often checked in organophosphate-poisoned patients. The activity of SChE decreases in OP poisoning cases, and the sensitivity is close to 100% for cases with significant OP poisoning.[2]

However, the significance of estimation of SChE activity to assess the severity of illness and prognosis in patients with OP compound poisoning is not conclusive in previous studies.[20],[21] There is a certain amount of ambiguity in the current data as far as the usefulness of SChE in prognosis of OP poisoning is concerned. This prompted us to demonstrate the value of SChE levels as a prognostic marker for patients with OP poisoning.


  Materials and Methods Top


Sampling procedure

The total number of OP poisoning cases in the last 3 years was 220 according to the Department of Medical Records, Hospital and Research Centre. Considering 80% of the annual average number of cases with OP compound poisoning during the last 3 years, the sample size was determined as a minimum of 60 cases. However, during the study period, 85 cases were admitted with OP compound poisoning, all of whom were included in the study.

This study of 85 patients with OP compound poisoning was conducted in the Department of Medicine, from January 2014 to December 2014.

Selection criteria

Inclusion

  • Patients with OP compound poisoning only.


Exclusion

  • Chronic liver disease (CLD)
  • Burns
  • Nephrotic syndrome
  • Pregnancy
  • Cases associated with additional consumption of alcohol, sleeping pills
  • Patients with comorbid conditions such as ischemic heart disease, chronic kidney disease, and CLD.


Method of collection of data

Demographic data such as age and sex were recorded. Patients/relatives were interviewed for chief complaints and past history. History of OP compound including type of OP compound, quantity consumed, route of exposure, and intention of consumption were noted as reported by either the patient or informant. A thorough physical, clinical, and systemic examination was carried out. Based on these findings, POP scale clinical criteria score was calculated. These findings were recorded on a predesigned and pretested pro forma.

Study variables

The patients were evaluated for the following study variables.

Severity of organophosphate compound poisoning

The severity of OPC poisoning was determined by POP scale clinical criteria score. The POP scale assesses the severity of the poisoning based on the symptoms at presentation and is simple to use.[17] The confirmation of the presence of organophosphorous poison in the blood was done by the Forensic Department.

Serum cholinesterase levels

The estimation of SChE levels was done by PCHE method using Flex reagent cartridge manufactured by Siemens Dimension clinical chemistry system. Pseudocholinesterase levels were estimated at the time of admission and during follow-up of the patient on the 5th day of hospital stay as well as at the time of discharge. The SChE levels between 7000 and 19,000 U/L were regarded as normal.[22] The trend of change in SChE levels from admission to discharge was also noted. The SChE was estimated instead of the RBC cholinesterase levels for the ease of estimation of the former, and the main purpose of the study was to find out an association between cholinesterase levels and clinical outcome in patients of OP compound poisoning. This study provides vital information for clinical evaluation in the resource-deficient hospitals where estimation of RBC cholinesterase levels may not be possible.

Ventilatory support and duration of ventilation

Number of patients requiring ventilation and duration of ventilatory support in each patient were noted.

Complications

Patients were monitored for the complications during their stay in the hospital.

Length of stay in the hospital

The duration of hospital stay was recorded.

Outcome

Patients were evaluated for the outcome as survivors and nonsurvivors.

Treatment protocol

Decontamination of the patient was done in the emergency department. All clothing and accessories were removed and placed in appropriate waste bags. The patient was washed with copious amount of water and soap.

Gastric lavage was done for all patients after the vitals were recorded and stabilized.

Injection atropine 0.6 mg to 1.0 mg was given IV stat. The dose of atropine initially given was low so as to cater for milder cases and then rapidly escalated (doubled each time in 5 min intervals) to achieve atropinization quickly. The peak effect of atropine was seen within 3 min of an intravenous (IV) injection. Once the target end points were achieved, i.e., clear chest, heart rate >80/min, and systolic blood pressure >90 mmHg, the patients were put on atropine infusion. Infusion of atropine reduced the fluctuation in atropine concentration associated with repeated bolus doses. The rate of infusion was set at 10% of the total atropine dose required to achieve atropinization. The maintenance atropine therapy was maintained for 24–48 h or longer in severe cases and gradually withdrawn over 3–5 days.

Injection PAM was initially given as a bolus dose of 2 g IV (30 mg/kg) over 30 min. Followed by 1 g IV every 8 h in mild to moderate poisoning and in severe poisoning cases, 500 mg/h (8–10 mg/kg/h) till clinical recovery (12–24 h after atropine was no longer required or after the patient was extubated) or 7 days whichever is later.

Indications for ventilator support

  1. Arterial oxygen tension <50 mmHg on room air
  2. Arterial CO2 tension >50 mmHg in the absence of metabolic alkalosis
  3. PaO2/FiO2 <250 mmHg
  4. Respiratory rate >35 breaths/min
  5. Tidal volumes <5 ml/kg
  6. Vital capacity <15 ml/kg
  7. Maximum inspiratory force <25 cm of H2O.


Discharge criteria

  • Normal SChE activity
  • Asymptomatic for the last 48 h after the last dose of atropine
  • Normal physical examination findings and vitals stable.


Statistical analysis

The data obtained were coded and entered into Microsoft Excel Worksheet (Annexure III). Data were analyzed using Statistical Package for the Social Sciences Version 20.0. The categorical data were expressed as rates, ratios, and proportions; comparison was done using either Chi-square test or Fisher's exact test. The continuous data were expressed as mean ± standard deviation, and comparison was done using independent sample t-test. P ≤ 0.05 was considered as statistically significant.


  Results Top


Patients age ranged from 18 to 87 years; maximum number of cases were in the age group of below 30 years, that is, 47 patients (55.29%), between 51 and 60 years – 14 cases (16.47%), 31–40 years – 12 cases (14.12%), 41–50 years – 9 cases (10.59%), and only 3 cases (3.53%) in the age group of more than 60 years.

Of 85 patients, 60 (70.59%) were males and 25 patients (29.41%) were females, accounting a ratio of male to female 2.4:1.

In the present study, we observed that 21 patients (24.71%) had consumed malathion, 14 patients (16.47%) had consumed chlorpyrifos, 14 patients (16.47%) – parathion, nine patients (10.59%) – fenthion, five patients (5.88%) – dimethoate, four patients (4.71%) – dichlorvos, three patients (3.53%) – diazinon, two patients (2.35%) – monocrotophos, one patient (1.18%) – fenchlorophos, one patient (1.18%) – methyl parathion, and in 11 patients (12.94%), the compound was unknown.

We observed that most of the patients 53 (62.35%) arrived between 3 and 6 h of consumption, 31 patients (36.47%) arrived within <3 h, and only one patient arrived after 6 h.

In our study, majority of patients presented with one or the other symptoms of poisoning. 74 patients (87.06%) had vomiting, 60 patients had sweating (70.59%), 57 patients had breathlessness (67.06%), 53 patients had diarrhea (62.35%), 46 patients had muscle twitching (fasciculations) (54.12%), and 2 patients had seizures (2.35%).

In our study, we observed that 26 patients (30.59%) had mild intoxication, 50 patients (58.82%) had moderate intoxication, and nine patients (10.59%) had severe intoxication (as per POP Score).

A total of 26 patients had various complications; acute renal failure was the most common complication observed in the study, i.e., six patients (23.08%). The other commonly encountered complications were intermediate syndrome in five patients (19.23%), respiratory failure in five patients (19.23%), and cardiac arrhythmia in four patients (15.38%) (2 ventricular tachycardia and 2 QTc prolongation). In the present study, there was no occurrence of any case of ventilator-associated pneumonia.

ECG tracing revealed that 60 patients had sinus bradycardia at admission, six patients had sinus tachycardia, and in remaining 19 patients, it was normal. During the hospital stay, 81 patients had sinus tachycardia because of treatment with atropine; however, two patients developed ventricular tachycardia and 2 had QTc prolongation.

In our study, we observed that 38 patients had an increasing trend of SChE levels and 21 patients had a decreasing trend of SChE levels; however, in 26 patients, it was not possible as some patients got discharged and some patients expired during serial estimation.

In our study, 72 patients (84.71%) survived, and the remaining 13 patients (15.29%) expired.

We observed that of 85 patients, 13 patients expired (15.29%). They had different causes such as, four patients had Intermediate syndrome (30.77%), three patients had respiratory failure (23.08%), two patients died of pulmonary edema (15.38%), two patients had acute renal failure (15.38%), one patient had cardiac arrhythmia (7.69%), and one patient expired due to shock (7.69%).

Time interval from consumption of organophosphorus compound to arrival at hospital

We observed that most of the patients 53 (62.35%) arrived between 3 and 6 h of consumption, 31 patients (36.47%) arrived within <3 h, and only one patient arrived after 6 h.

In our present study, association of SChE with severity of poisoning based on POP score revealed that a total of 50 patients had moderate intoxication, 26 patients had mild intoxication, and nine patients had severe intoxication as shown in [Table 1]. P < 0.001 was considered as statistically significant.
Table 1: Association of serum cholinesterase with severity of poisoning based on peradeniya organophosphorus poisoning score (n=85)

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In our study, we assessed the association of POP scoring with hospital stay as shown in [Table 2]. P < 0.001 was considered as statistically significant.
Table 2: Association of peradeniya organophosphorus poisoning scoring with hospital stay

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In our present study, we assessed the association of 1st-day SChE with days of hospital stay as depicted in [Table 3]. P < 0.001 was considered as statistically significant.
Table 3: Association of 1st-day serum cholinesterase with hospital stay

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Attempt to compare mean hospital stay with serial estimation of SChE showed stay of patients was 11.50 ± 3.51 days in patients with decreasing trend of SChE as compared to 9.40 ± 3.84 days in patients with increasing trend. P =0.043 was considered as statistically significant.

In our present study, of 59 patients, 38 patients had increasing trend of SChE levels and 21 patients had decreasing trend of cholinesterase levels as depicted in [Table 4]. In patients with increasing trend of SChE, there was no death observed, and in decreasing trend, five patients expired. P = 0.0080 was considered as statistically significant.
Table 4: Difference between serial estimation of serum cholinesterase with hospital stay

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[Table 5] depicts the percentage of complications with various levels of cholinesterase done on day 1. P = 0.183 was considered as statistically insignificant.
Table 5: Association of 1st-day serum cholinesterase with complications

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In our present study of 85 patients, 63 patients did not require ventilatory support, remaining 22 patients required ventilatory support for various reasons (six patients of acute renal failure, five patients of intermediate syndrome, five patients of respiratory failure, three patients of cardiac arrhythmia, two patients of pulmonary edema, and one patient with shock). P = 0.0070 was considered as statistically significant.

Association of serial estimation of SChE with ventilatory support revealed that a higher percentage of patients with decreasing trend of SChE levels required ventilatory support than the patients with increasing trend as shown in [Table 6]. P = 0.097 was considered as statistically insignificant.
Table 6: Association of serial estimation of serum cholinesterase with ventilatory support

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In our study, 1st-day estimation of SChE was associated with overall outcome of patients which is shown in [Table 7]. P = 0.1832 was considered as statistically insignificant.
Table 7: Association of 1st-day serum cholinesterase with outcome

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  Discussion Top


In the present study of 85 patients with OP compound poisoning, a correlation between SChE levels and clinical outcome was studied, and the same was compared with the POP scoring system and other variables.

All the 85 patients who presented with OP compound poisoning were with a suicidal bid. This is similar to a study done by Khazi et al.[23]

In our study, patient age ranged from 18 to 87 years. Maximum number of cases were in the age group of below 30 years, i.e., 47 patients (55.29%). This is similar to study done by Sen et al.,[24] Rehiman et al.,[25] and Patil et al.[26]

When sex was taken into consideration, we observed that 60 males and 25 females were present in the study group. There was male preponderance with a ratio of male to female – 2.4:1. This observation is similar to the study by Kang et al.[19] and Patil et al.[26] In contrast, Rehiman et al.[25] and Sen et al.[24] observed more number of females in their study.

We tried to analyze our patients with the OP compounds they had consumed. The commonly consumed compounds were malathion in 21 patients (24.71%), chlorpyrifos in 14 patients (16.47%), and parathion in 14 patients (16.47%). In studies by Nouira et al.[27] and Rehiman et al.,[25] the most commonly consumed compounds were parathion and dichlorvos. In contrast, a study by Kumar et al.[22] found that the most commonly consumed compounds were monocrotophos and chlorpyrifos.

Similarly, we tried to analyze the time of consumption to arrival at the hospital. We had 53 patients (62.35%) who presented after 3–6 h of consumption, 31 patients (36.47%) within 3 h, and only one patient after 6 h. Nouira et al.[27] observed that in their study, patients presented within a mean time interval of 2.5 h (range, 30 min to 15.5 h).

Patients presented with various symptoms of OP compound poisoning. Majority 74 patients (87.06%) had vomiting, 60 patients (70.59%) had sweating, 57 patients (67.06%) had breathlessness; other symptoms were diarrhea in 53 patients (62.35%), muscle twitching in 46 patients (54.12%), and only two patients presented with seizures. Similarly, studies by Nouira et al.[27] and Venkateshwarlu et al.[28] observed combination and permutation of symptoms of nausea, vomiting, fasciculations, diarrhea, etc.

An attempt to study clinical presentation based on POP score revealed severe intoxication in nine patients (10.59%), moderate intoxication in 50 patients (58.82%), and mild intoxication in 26 patients (30.59%). The same is depicted in [Table 8] (POP score) and [Table 6] (severity). This is in contrast with study by Rehiman et al.[25] who observed 70% of their cases had mild intoxication, 26% cases had moderate intoxication, and only 4% cases had severe intoxication.
Table 8: Association of 1st-day serum cholinesterase with ventilatory support (n=85)

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We observed various complications of OP compound poisoning: acute renal failure in six patients (23.08%), intermediate syndrome in five patients (19.23%), respiratory failure in five patients (19.23%), and cardiac arrhythmia in four patients (15.38%) (2 ventricular tachycardia and 2 QTc prolongation). This is in contrast to a study by Venkateshwarlu et al.[28] who observed that pulmonary edema was the most common complication seen in their patients. Sen et al.[24] found respiratory acidosis to be the most common complication followed by intermediate syndrome.

In our study, all 85 patients were subjected to ECG tracing at arrival and during their stay in the hospital which is shown in [Table 9]. Yun et al.[29] had made an attempt to study QTc prolongation and its correlation with mortality in their patients. A statistically insignificant difference was found between the mean QTc intervals of the patients who survived and those who expired.
Table 9: Association of serial estimation of serum cholinesterase with outcome of patients

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An attempt was made to study various laboratory parameters in our patients. SChE estimation done on serial days (i.e., day 1, day 5, and at discharge) revealed various levels on different days. A study by Prasad et al.[12] revealed similar observations.

Taking renal functions into consideration, all six patients who developed acute renal failure had elevated urea and creatinine levels. Remaining 79 patients had normal urea and creatinine levels. Three patients with acute renal failure were subjected to hemodialysis and 3 were not. One patient expired in each group.

Kang et al.[19] had subjected their patients for hemoperfusion and found that it was ineffective in terms of survival and improvement of patients with OP compound poisoning. Study by Altintop et al.[30] reported hemoperfusion to be useful in severe cases. This is by a proposed mechanism that activated charcoal or resins used for hemoperfusion may help in purifying the blood, thus allowing the patients to improve. We did not attempt hemoperfusion in any of our patients since there was no definite evidence of benefit in terms of morbidity or mortality.

We subjected our patients to liver function tests, and all of them presented with grossly normal serum bilirubin, serum glutamic oxaloacetic transaminase, serum glutamic pyruvic transaminase, and alkaline phosphatase. In our study, we have safely avoided patients with known liver disease (CLD is known to affect SChE levels). Patil et al.[26] have also excluded patients with known liver disease in their study.

Serial estimation of SChE levels (day 1, day 5, and at discharge) was done on the patients. The trends and details of which can be seen in the [Graph 1]. Among the 59 patients, 38 patients (64.40%) had an increasing trend and 21 patients (35.60%) had a decreasing trend. In the remaining 26 patients, it was not possible to study the trend as some got discharged and some expired during serial estimation. Studies by Kumar et al.[22] and Yun et al.[29] have also attempted similar estimation and analysis of SChE levels.



In our study, the outcome of patients was evaluated and we found that 13 patients (15.29%) had expired and 72 patients (84.71%) had survived. A study by Kang et al.[19] found almost similar outcomes of patients. In contrast, Siva et al.[2] had observed a significantly higher percentage of deaths in their study.

An attempt to find out the various causes of death in our patients revealed intermediate syndrome in four patients (30.77%), respiratory failure in three patients (23.08%), pulmonary edema in two patients (15.38%), acute renal failure in two patients (15.38%), cardiac arrhythmia in one patient (7.69%), and shock in one patient (7.69%). Studies [12],[23],[24],[25],[26],[27],[28],[29],[30] by different authors have not commented on the causes of death.

In our study, a statistically significant correlation was found between SChE levels and severity of poisoning based on POP score (P < 0.001). This is similar to a study done by Khazi et al.[23] Another study by Sen et al.[24] also reported significant correlation, but in their study comparison was done not only with SChE; other parameters such as Creatinine Phospho Kinase (CPK) and Lactate De-Hydrogenase (LDH) were also taken into account.

An attempt to correlate POP scoring with hospital stay of patients showed a significant correlation as shown above (P < 0.001; statistically significant). Similar observations were made by Rehiman et al.[25] and Manu et al.[31]

We observed that 1st-day SChE was directly correlating with hospital stay which is depicted above (P < 0.001; statistically significant) Similar observations were made by Khazi et al.[23] and Rehiman et al.[25] wherein a significant correlation was established between deranged SChE level and morbidity of the patients in terms of prolonged duration of hospital stay.

We also attempted a correlation of SChE estimation on serial days which showed a significant correlation of SChE with hospital stay. Mean hospital stay was 9.40 ± 3.84 days in patients with an increasing trend of SChE levels whereas in patients with a decreasing trend, the mean hospital stay was 11.50 ± 3.51 days (P = 0.043; statistically significant).

When we attempted to correlate levels of SChE on 1st day with complications, we found that there were more complications in patients whose levels were ≤2500 U/L, i.e., 20 patients (37.74%) as well as in those with levels between 2501 and 5000 U/L i.e., three patients (30.00%). However, P = 0.183 was statistically insignificant. Different authors have not correlated levels of SChE with complications.

A comparison between 1st-day SChE estimation and ventilatory support is depicted above. Of the 53 patients with SChE levels ≤2500 U/L, 18 patients (33.96%) required ventilatory support. Similarly, three patients (30.00%) with a SChE of 2501–5000 U/L and only one patient (5.56%) with SChE of 7001–19,000 required ventilatory support (P = 0.047; statistically significant). Studies by Khazi et al.,[23] Kumar et al.[22] and Prasad et al.[12] have also found correlation between 1st-day SChE estimation and ventilatory support.

Correlation of serial estimation of SChE with ventilatory support showed that eight patients (38.10%) with a decreasing trend of SChE levels required ventilatory support as opposed to seven patients (18.42%) with an increasing trend. However, it did not have a significant P value (P = 0.097). A similar study by Goswamy et al.[20] found significant correlation between serial estimation of SChE and patients requiring ventilatory support. They found that low SChE levels have greatest predictive value for mechanical ventilation. A study by Nouira et al.[27] did not find any correlation between low levels of SChE and requirement of ventilatory support.

Similarly, we tried to correlate 1st-day SChE estimation with outcome (P = 0.451; statistically insignificant). In a study by Rehiman et al.,[25] it was observed that SChE levels at presentation did not correlate with mortality. In contrast, studies by Kumar et al.,[22] Patil et al.,[26] and Prasad et al.[12] have found a significant correlation between 1st-day SChE and mortality.

Finally, correlation of serial estimation of SChE with outcome of patients was done. In patients with an increasing trend of SChE levels in 38 patients (100%), all survived and none expired whereas in patients with a decreasing trend, 16 patients (76.19%) survived and five patients (23.81%) expired (P = 0.004; statistically significant). Similarly, Yun et al.[29] and Chen et al.[32] noted a statistically significant relationship between dynamic changes of SChE activity and mortality.

In our present study with a small sample size of 85 patients, we observed a significant correlation of SChE when compared to hospital stay of patients (estimation at arrival and serial estimation). When compared to ventilated patients, the correlation was also significant (1st day but not on serial estimation). Taking overall outcome into account, it was found to be significant on serial estimation of SChE (but not on 1st-day estimation).


  Conclusion Top


In our present study of 85 patients with OP compound poisoning, we observed various clinical manifestations, and the same were compared with the POP scoring system. Levels of SChE were correlated with various variables such as hospital stay, complications, ventilatory support, and outcome.

We found statistically significant correlation between SChE and hospital stay in days (1st day levels and serial estimation); SChE and requirement of ventilatory support (1st day levels alone); and SChE and outcome (serial estimation alone). Similarly, the correlation between SChE and complications was not statistically significant.

The various complications, the longer hospital stay and a higher mortality, all correlate with the lower initial level of SChE and its decreasing trend during serial estimation.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
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  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7], [Table 8], [Table 9]



 

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