Peritonitis index as a tool for predicting progression and optimizing surgical management in diffuse peritonitis

Objective: to assess the prognostic applicability of the Peritonitis Index (PI) for risk stratification of postoperative progression in diffuse peritonitis and to describe the association between risk strata and the postoperative management strategies employed.

Material and methods: a retrospective analysis of the clinical data of 188 patients who underwent surgery in 2016-2025 at the Varorud Medical and Diagnostic Center and the State Institution Dushanbe City Emergency Medical Care Center was performed. The patients were aged 15-81 years; 113 (60.1%) were men and 75 (39.9%) were women. The Peritonitis Index (PI) was calculated as the sum of three components: risk factors (F), stage of the process (S), and morphological changes of the peritoneum (V), with a total score ranging from 6 to 30 points. The patients were stratified into three groups: group I, PI ≤12; group II, PI 13-22; and group III, PI >22. The main outcomes were progression of peritonitis, repeat interventions, and death. Statistical analysis was performed in R version 4.5.2. Quantitative data are presented as Me [Q1-Q3], and categorical data as n (%). The chi-square test, Fisher’s exact test, logistic regression, and ROC analysis were used.

Results: progression of peritonitis was identified in 67 of 188 patients (35.6%). The frequency of progression increased with increasing PI: 3/86 (3.5%) in group I, 31/62 (50.0%) in group II, and 33/40 (82.5%) in group III (p < 0.001). In the logistic model, each 1-point increase in PI increased the odds of progression (OR = 1.32; 95% CI 1.23-1.42; p < 0.001). ROC analysis confirmed the high discriminative ability of the PI for progression (AUC = 0.878). Among the 67 patients with progression, repeat interventions were performed in 54 (80.6%): relaparotomy on demand in 42 (62.7%) and scheduled abdominal re-explorations in 12 (17.9%); in 13 cases (19.4%), death occurred without repeat surgery. For mortality among patients with progression, the discriminative ability of the PI was moderate (AUC = 0.656).

Conclusions: PI is a useful tool for risk stratification of diffuse peritonitis progression and may be used as an adjunct for clinical assessment. Prospective studies with calibration assessment and internal/external validation are required before using PI for decision-making.

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