A nomogram to predict carbapenem-resistant Pseudomonas aeruginosa isolation in patients with exacerbations of bronchiectasis

The rising isolation of carbapenem-resistant Pseudomonas aeruginosa (CRPA) among patients with bronchiectasis complicates clinical management. We developed and internally validated a nomogram to estimate the probability of CRPA isolation. We conducted an observational, retrospective cohort study for bronchiectasis patients with Pseudomonas aeruginosa (PA) isolation at West China Hospital of Sichuan University between January, 2010 and July, 2024. Patients were stratified into CRPA and Non-CRPA group based on antimicrobial susceptibility testing. Bivariable and multivariate logistic regression analyses, nomogram analyses were employed to independent risk factors for CRPA isolation, and model performance was evaluated through receiver operating characteristic (ROC) and calibration curves. The study included 916 PA-positive patients, of whom 164 (17.90%) harbored CRPA. The multivariable logistic regression identified these factors: chronic obstructive pulmonary disease (COPD) (adjusted odds ratio [aOR] = 2.951, p < 0.001), hypertension (aOR = 2.403, p = 0.001), diabetes mellitus (DM) (aOR = 1.982, p = 0.025), modified medical research council dyspnea scale (mMRC) score (aOR = 1.271, p = 0.019), immunosuppressive therapy (aOR = 1.894, p = 0.020), Cand ida albicans (aOR = 2.232, p < 0.001), platelet count (aOR = 1.006, p < 0.001), and absolute neutrophil count (ANC) (aOR = 1.239, p < 0.001), albumin (aOR = 0.945, p = 0.010). A nomogram incorporating these factors demonstrated strong discriminative ability as evidenced by the ROC curve and excellent calibration curve. COPD, hypertension, DM, mMRC score, immunosuppressive therapy, Candida albicans , albumin, platelet and ANC are key independent factors associated with CRPA isolation in bronchiectasis. The proposed nomogram may help clinicians identify patients at high risk of CRPA isolation and facilitate timely microbiological testing, with the potential to improve clinical outcomes.