Development and validation of a predictive nomogram for the risk of recurrence in patients with cystitis glandularis

Background: Most patients with cystitis glandularis (CG) suffer from recurrence after primary treatment. Therefore, we performed this multicenter study to clarify the recurrent risk factors and constructed a predictive nomogram for the risk of recurrence. Also, we try to investigate the correlation between CG and bladder cancer. Methods: Consecutive patients with pathologically confirmed CG were divided into training and validation sets. Clinicopathological characters were collected from electronic medical records. Uni- and multivariate logistic regression analyses were used to identify independent risk factors of CG recurrence in the training set. The predictive nomogram was developed by incorporating these independent factors and histological subtype. The performance of the nomogram was assessed and validated with respects to its calibration, discrimination, and clinical usefulness. The risk of developing subsequent bladder cancer was analyzed from the follow-up data. Results: Ultimately, 278 eligible patients were included and were allocated to a training set (n=190) and a validation set (n=88). Of them, 165 (59.35%) patients experienced CG recurrence, and none showed evidence of subsequent bladder carcinoma during a median (IQR) follow-up time of 27 months (14-57 months). Results of multivariate analysis showed that urinary infections, long-term indwelling catheter usage, urinary calculus, squamous metaplasia, and atypical hyperplasia were independent risk factors of CG recurrence. The C-index (95% CI) of the nomogram was 0.76 (0.69-0.83) in the training set and 0.72 (0.61-0.83) in the validation set. A decision curve analysis (DCA) demonstrated that this predictive nomogram was clinically useful. Conclusions: We developed and validated a nomogram to predict the individualized risk of CG recurrence. Also, we demonstrated that neither intestinal nor typical CG increased the consequent risk of bladder cancer during the follow-up period.