Correlation between carbapenem susceptibility in Pseudomonas aeruginosa and modified antibiotic heterogeneity index: a multicenter observational study using a surveillance platform

Objective: This study focused on exploring the relationship between antimicrobial use indicators, including the modified antibiotic heterogeneity index (mAHI), and the carbapenem susceptibility in Pseudomonas aeruginosa. Design: Survey-based observational study conducted across multiple facilities. Setting: Public community hospital institutions. Methods: This survey was conducted in 15 community hospitals in Japan. Indicators, such as the defined daily doses (DDDs), days of therapy (DOTs), antibiotic heterogeneity index (AHI), and mAHI, were analyzed for P. aeruginosa carbapenem susceptibility using Spearman's rank correlation. The predictive accuracies of the AHI and mAHI for carbapenem susceptibility were compared using DeLong's test for the 2 correlated receiver operating characteristic curves. Results: No significant correlations were observed between DDDs or DOTs and carbapenem susceptibility. However, a significant correlation was observed between carbapenem susceptibility and the mAHI (r = 0.261, P = .02), which also demonstrated a higher predictive accuracy for high susceptibility rates than that of the AHI (area under the curve: 0.75 vs 0.58, p < .01). The optimal mAHI cutoff value for predicting 90% susceptibility was 0.765, with a sensitivity of 67.7% and specificity of 76.5%. Conclusions: The mAHI may be a better predictor of carbapenem susceptibility than other commonly used indicators. This study underscores the utility of the mAHI as an effective indicator of antimicrobial usage patterns for managing carbapenem susceptibility in P. aeruginosa. Incorporating the mAHI into antimicrobial stewardship programs could enhance the effectiveness of antimicrobial interventions across diverse healthcare settings.