The Novel "RISC" Score as a Risk-prediction Model of Carbapenem-resistant Hospital-acquired Infections in Adult Sepsis Patients - A Prospective Observational Study

Abstract

Aim and background: Antimicrobial sensitivity (AMS) reports are often available after 72 hours of identification of gram-negative (GN) hospital-acquired infection (HAI). Prediction of carbapenem-resistant infection (CRI) among GN strains is important even before AMS reports are available, for judicious use of empirical antibiotics. We aimed to study the predictors of CRI in patients with HAI.

Materials and methods: We conducted a single-center prospective observational study between April 2023 and September 2024 on patients of GN sepsis with HAI. The use of empirical carbapenem antibiotics, organ dysfunction scores, the modified nutritional risk in critically ill (mNUTRIC) score, blood-count-derived inflammation indices, type of HAI, AMS reports, and in-hospital mortality were noted.

Results: A total of 935 sepsis patients with HAI were screened, and there were 195 patients with GN infection. Among the 195 patients, 145 (74.4%) had CRI and 50 (25.6%) had non-CRI. Multivariable logistic regression revealed that the length of intensive care unit (ICU) stay before the day of HAI (p = 0.009, adjusted odds ratio (OR) 1.155, 95% confidence interval (CI) 1.037-1.286), presence of ventilator-associated pneumonia (VAP) (p-value < 0.001, adjusted OR 4.170, 95% CI: 1.858-9.361), empirical carbapenem antibiotics before the day of HAI (p-value = 0.004, adjusted OR 3.164, 95% CI: 1.439-6.957), and septic shock on the day of HAI (p-value 0.012, adjusted OR 4.162, 95% CI: 1.366-12.677) were the independent risk factors of CRI.

Conclusion: In GN sepsis patients with HAI, respiratory infection (VAP), length of ICU stay prior to HAI, septic shock, and empirical carbapenem antibiotic administration are risk factors of CRI.

How to cite this article: Mareguddi AB, Chaudhuri S, Shanmukhappa SM, Parampalli V, Bhatt MT, Fernandes R, et al. The Novel "RISC" Score as a Risk-prediction Model of Carbapenem-resistant Hospital-acquired Infections in Adult Sepsis Patients - A Prospective Observational Study. Indian J Crit Care Med 2025;29(4):352-362.

Keywords: Carbapenem-resistant infection; Gram-negative sepsis; Hospital-acquired infection; Predictors.

Fig. 1

Flowchart depicting the recruitment of HAI patients

Fig. 2

The methodology followed to identify HAI due to CRI

Fig. 3

The ROC curve depicting the AUC of the new “RISC” score to predict CRI among HAI patients with GN sepsis (diagonal segments are produced by ties). AUC 0.891, p-value < 0.001. 95% CI: (0.845–0.938), cut-off ≥8, sensitivity 93.1%, specificity 64%, diagnostic accuracy 85.64%, positive likelihood ratio 2.59, PPV 88.24%, and NPV 76.19%. AUC, area under curve; CI, confidence-interval; ICU, intensive-care unit; ROC, receiver operating characteristic; “RISC” score, Respiratory infection (VAP), length of stay in ICU ≥ 3 days before day of HAI, Septic shock, empirical carbapenem antibiotic use empirically

Fig. 4

Bar diagram depicting patients with high “RISC” score ≥8 and presence of CRI among the patients of HAI. Bar diagram depicting that among the 153 patients who had a high RISC score (≥8), 135 (88.2%) of the patients had CRI, whereas among the 42 patients with a low RISC score (<8), only 10 patients (23.8%) had CRI. The purple bar indicated CRI present and the green bar indicates CRI absent. “RISC” score, Respiratory infection (VAP), length of stay in ICU ≥ 3 days before day of HAI, Septic shock, empirical carbapenem antibiotic use empirically

Fig. 5

The relationship map between the patients with CRI and “RISC” scores and non-CRI and RISC scores. The red circle labelled “1” indicates the presence of CRI and the red circle labelled “0” indicates the absence of CRI. The blue circles indicate the total RISC score values. The blue lines connecting the red circles with the blue circles indicate the strength of association between CRI and a high RISC score. This relationship map indicated that high RISC scores (8–12) are associated with CRI, whereas low RISC scores (0–7) are associated with an absence of CRI. “RISC” score, Respiratory infection (VAP), length of stay in ICU ≥3 days before day of HAI, Septic shock, empirical carbapenem antibiotic use empirically. The factors CRIV in the “RISC score” refers to empirical carbapenem use, respiratory infection, ICU stay >3 days and vasopressor use due to septic shock