Objective: To identify clinical variables associated with a positive computed tomography (CT) scan and estimate the performance of imaging recommendations in patients from a diverse sample of urology practices.
Materials and methods: This study comprised 2380 men with newly diagnosed prostate cancer seen at 28 practices in the Michigan Urological Surgery Improvement Collaborative from March 2012 through September 2013. Data included age, prostate-specific antigen (PSA) level, Gleason score (GS), clinical T stage, total number of positive biopsy cores, whether or not the patient received a staging abdominal and/or pelvic CT scan, and CT scan result. We fit a multivariate logistic regression model to identify clinical variables associated with metastases detected by CT scan. We estimated the sensitivity and specificity of existing imaging recommendations.
Results: Among 643 men (27.4%) who underwent a staging CT scan, 62 men (9.6%) had a positive study. In the multivariate analysis, PSA, GS, and clinical T stage were independently associated with the occurrence of a positive CT scan (all P values <.05). The American Urological Association's Best Practice Statements' recommendations for imaging when PSA level >20 ng/mL or GS ≥ 8 or locally advanced cancer had a sensitivity of 87.3% and specificity of 82.6%. Compared with current practice, implementing this recommendation in the Michigan Urological Surgery Improvement Collaborative population was estimated to result in approximately 0.5% of positive study results being missed, and 26.1% of fewer study results overall.
Conclusion: Successful implementation of CT imaging criterion of PSA level >20, GS ≥ 8, or clinical stage ≥ T3 would ensure that CT scans are performed for almost all men who would have positive study results while reducing the number of negative study results.
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