The prognostic performance of the predisposition, infection, response and organ failure (PIRO) classification in high-risk and low-risk emergency department sepsis populations: comparison with clinical judgement and sepsis category

Objective To compare the prognostic performance of the predisposition, infection, response and organ failure (PIRO) score with the traditional sepsis category and clinical judgement in high-risk and low-risk Dutch emergency department (ED) sepsis populations. Methods Prospective study in ED patients with severe sepsis and septic shock (high-risk cohort), or suspected infection (low-risk cohort). Outcome: 28-day mortality. Prognostic performance of PIRO, sepsis category and clinical judgement were assessed with Cox regression analysis with correction for quality of ED treatment and disposition. Illness severity measures were divided into four groups with the lowest illness severity as reference category; discrimination was quantified by receiver operator characteristics with area under the curve (AUC) analysis. Results Death occurred in 72/323 (22%, high-risk) and 23/385 (6%, low-risk) patients. For the low-risk cohort, corrected HRs (95% CI) for categories 2-4 were 2.0 (0.4 to 11.9), 4.3 (0.8 to 24.7) and 17.8 (2.8 to 113.0: PIRO); 0.5 (0.05 to 5.4), 2.1 (0.2 to 21.8) and 7.5 (0.6 to 92.9: sepsis category). Patients discharged home (category 1) all survived. HRs were 4.5 (0.5 to 39.1) and 13.6 (4.3 to 43.5) for clinical judgement categories 3-4. Prognostic performance was consistently better in the low-risk than in the high-risk cohort. For PIRO AUCs were 0.68 (0.61 to 0.74; high-risk) and 0.83 (0.75 to 0.91; low-risk); for sepsis category AUCs were 0.50 (0.42 to 0.57; high-risk) and 0.73 (0.61 to 0.86; low-risk); for clinical judgement AUCs were 0.69 (0.60 to 0.78; high-risk) and 0.84 (0.73 to 0.96; low-risk). Conclusions The accuracy and discriminative performance of the PIRO score and clinical judgement are similar, but better than the sepsis category. Prognostic performance of illness severity scores is less in high-risk cohorts, while in high-risk populations a risk stratification tool would be most useful.