Evaluation of Usefulness of Mannheim Peritonitis Index and APACHE II Score in Predicting Mortality and Morbidity in Patients with Peritonitis- A Prospective Diagnostic Test Study

Introduction: Peritonitis, defined as inflammation of the peritoneal cavity can be of various causes, and is one of the most common surgical emergencies. This continues to be a challenge to diagnose and treat. Early intervention is essential to select patients who will need intensive care which brings out better outcome for the patients. This also helps us use the resources optimally. Over years, many scoring systems have been developed and studied to predict outcomes in patients with peritonitis. Aim: To evaluate the ability of Mannheim Peritonitis Index (MPI) and APACHE II (Acute Physiology And Chronic Health Evaluation II) scores in predicting mortality and morbidity in patients with peritonitis. Materials and Methods: A prospective, observational study was conducted at Christian Medical College and Hospital, Vellore, Tamil Nadu, India, for a period of two years from September 2014 to August 2016. A total of 78 patients were recruited for this study. These patients were scored with MPI and APACHE II scores. The primary outcome studied was in hospital death or discharge. The secondary outcome studied was morbidity in terms of local and systemic complications. The risk factors associated with mortality in patients with peritonitis were also studied. The best cut-off value for MPI and APACHE II from the data was calculated using Yuden index. The sensitivity, specificity and likelihood ratios were calculated and presented with 95% Confidence Interval(CI). The sub-group analysis was done for risk factors and complications. Results: There were more males than females. Age ≥48 years (p=0.002) and serum creatinine ≥1.3 g/dL (p=0.012) were found to be significant risk factors for mortality. The sensitivity and specificity of MPI ≥27 in predicting mortality was found to be 90% and 57% respectively. The sensitivity and specificity of APACHE II score ≥10 in predicting mortality was found to be 40% and 78%, respectively. MPI scores ≥27 were strongly associated with morbidity like prolonged ICU stay (p=0.004), mechanical ventilation requirement (p=0.001) and need for dialysis (p=0.035). Conclusion: Present study showed MPI to be a better predictor of mortality than APACHE II, though APACHE II showed better specificity. MPI score also was helpful in predicting morbidity such as prolonged ICU stay, mechanical ventilation requirement postoperatively and need for dialysis postoperatively. MPI was easier to use as it contained lesser variables. MPI could be of use in rural areas with no facility for laboratory investigations and blood gas analysis.