SERUM CREATININE PHOSPHKINASE VS PSEUDOCHOLINESTERASE AS A PROGNOSTIC MARKER IN ORGANOPHOSPHORATE POISONING - A CROSS SECTIONAL STUDY

Abstract

Background: Acute organophosphorus (OP) poisoning remains a high-burden emergency in South Asia, with outcomes driven by early cholinergic crisis, respiratory failure, and intermediate syndrome. While plasma pseudocholinesterase (PChE) is widely used as a biochemical surrogate of OP exposure, its prognostic reliability is limited by inter-individual variability and hepatic synthesis dependence. Creatinine phosphokinase (CPK), reflecting skeletal muscle injury and neuromuscular junction dysfunction, has been proposed as a pragmatic prognostic biomarker. This study compared serum CPK and PChE as predictors of in-hospital outcomes in OP poisoning.

Methods: A cross-sectional study was conducted over 3 months at RLJH Hospital (MICU/ICU/ward). Eighty adults (≥18 years) with clinically diagnosed OP poisoning were enrolled after informed consent. Patients with confounding comorbidities (myopathy, chronic liver disease, myocarditis/MI, chronic pancreatic disease, pregnancy, major psychiatric illness) were excluded. Serum CPK and PChE were measured at presentation and correlated with Peradeniya Organophosphorus Poisoning (POP) score and clinical outcomes (need for mechanical ventilation, intermediate syndrome, length of stay, and mortality). Statistical testing included chi-square/Fisher’s exact tests, t test/Mann–Whitney U, and Pearson/Spearman correlation; receiver operating characteristic (ROC) analysis was performed for prognostic performance.

Results: Among 80 patients (mean age 34.6±12.1 years; 62.5% male), 22.5% required ventilation and 12.5% died. Admission CPK rose stepwise with POP severity (mild: 182±64 IU/L; moderate: 356±110 IU/L; severe: 742±220 IU/L; p<0.001) and correlated strongly with POP score (r=0.79, p<0.001). PChE demonstrated an inverse association (mild: 5,180±1,240 U/L; moderate: 3,040±1,010 U/L; severe: 1,420±620 U/L; p<0.001; r=−0.66, p<0.001). For mortality prediction, CPK showed higher discrimination than PChE (AUC 0.86 vs 0.78).

Conclusion: In this cohort, serum CPK at presentation demonstrated stronger alignment with clinical severity and adverse outcomes than PChE, supporting CPK as a practical prognostic adjunct in OP poisoning, particularly where rapid risk stratification is required.