• A nonconcurrent prospective study of bladder calculi Included 500 persons treated at the University of Alabama in Birmingham Spinal Cord Injury Care System between 1973 and 1981. Risk factors suspected of contributing to the development of bladder calculi were identified. Logistic regression analysis was used to estimate each risk factor's adjusted odds ratio and to develop a predictive model for bladder stone formation. Bladder calculi were most likely to develop within one year of injury. Patients developing bladder calculi prior to first definitive discharge were most likely to be white and have neurologically complete lesions and Klebsiella infections at admission. Patients developing bladder stones within two years of hospital discharge were most likely to be young and white and have indwelling urethral catheters and either Proteus or multiple-organism infections at discharge. The predictive model was 82% sensitive and 83% specific when applied to a validation sample of patients.