Xiuyan Li,1,* Wanlin Lei,2,* Maofeng Wang,2 Lili Xu3 

1Intensive Care Unit, Affiliated Dongyang Hospital, Wenzhou Medical University, Dongyang, Zhejiang, 322100, People’s Republic of China; 2Department of Biomedical Sciences Laboratory, Affiliated Dongyang Hospital, Wenzhou Medical University, Dongyang, Zhejiang, 322100, People’s Republic of China; 3Department of Obstetrics, Affiliated Dongyang Hospital, Wenzhou Medical University, Dongyang, Zhejiang, 322100, People’s Republic of China

*These authors contributed equally to this work

Correspondence: Maofeng Wang, Email wzmcwmf@wmu.edu.cn Lili Xu, Email xulili41663@163.com

Objective: Third-generation cephalosporins, while widely prescribed, carry underquantified thrombocytopenia risks in older adults. This study aimed to develop and validate a clinical prediction model for cephalosporin-associated thrombocytopenia in hospitalized patients aged over 65 years.
Methods: A retrospective cohort (2019~2023) initially included 45,779 cephalosporin treated patients. After applying exclusion criteria, 12,917 patients were analyzed. Predictors were selected via LASSO regression, with backward elimination multivariate logistic regression constructing a nomogram. Model performance was assessed using AUC, calibration curves, and decision curve analysis (DCA) in training and testing sets.
Results: The final model identified eight predictors: baseline platelet count (PLT), red blood cell count (RBC), presence of tumor, renal insufficiency (RI), liver cirrhosis (LC), meropenem use, use of antifungal drugs (AD), and daily usage frequency (DUF). It demonstrated strong discrimination (training AUC 0.82 [95% CI 0.79– 0.85]; testing AUC 0.80 [0.76– 0.84]) and calibration (Brier score 0.057). DCA confirmed clinical utility across wide risk thresholds.
Conclusion: This nomogram tool enables rapid thrombocytopenia risk assessment in elderly patients receiving cephalosporins. Clinically, it guides antibiotic selection by quantifying comorbidity-drug interactions, and improves toxicity monitoring accuracy in complex geriatric cases with polypharmacy.

Keywords: thrombocytopenia, predictive model, geriatric inpatients, nomogram, third generation cephalosporins