A validation of different prognostic scoring systems in the prediction of outcome in peritonitis

Background and goal

Early classification of patients with peritonitis by means of scoring systems provides adequate selection for surgical and therapeutic procedures and comparison of different therapies [1]. We compared the prognostic value of APACHE II and SAPS II scoring systems as well as the Mannheim Peritonitis Index (MPI) for assessment of outcome in the patients with diffuse bacterial peritonitis.

Materials and methods

We enrolled 194 adult patients (mean age 49.6 ± 19.5 years) with secondary diffuse bacterial peritonitis in a prospective observational study during the period from 1999 to 2003. All patients were hospitalized in the ICU of the university hospital. The scores according to APACHE II, SAPS II, and MPI were assessed during 24 hours after admission to the ICU. The predictive values of the scores were estimated using regression analysis (coefficient of determination r²). The discrimination was assessed using areas under the receiver operating characteristic curves (AUCs). Standardized mortality ratios (SMRs) were calculated. Variables were expressed as mean ± standard deviation or 95% confidence interval and as relative frequencies.

Results and discussions

The mean APACHE II, SAPS II and MPI scores were 9.6 ± 8.4, 28.8 ± 16.7, and 23.9 ± 6.9, respectively. The hospital mortality rate was 19.1% (37 patients). The predicted mortality risk was 18.9%, 9.6%, and 33.6% for APACHE II (diagnostic category weight for gastrointestinal perforation/ obstruction), SAPS II and MPI, respectively. The values of calibration (P < 0.05) and discrimination and SMR are summarized in Table 1.

Table 1 Table 1

The calibration was adequate for APACHE II and SAPS II scores. The discrimination was good for all systems. The APACHE II score had the most accurate overall mortality prediction, as reflected by the SMR.

Conclusion

In patients with diffuse bacterial peritonitis, APACHE II is the most accurate prognostic scoring system as compared with SAPS II and MPI.