TY - JOUR
T1 - The nomogram conundrum
T2 - a demonstration of why a prostate cancer risk model in Turkish men underestimates prostate cancer risk in the USA
AU - Kara, Onder
AU - Elshafei, Ahmed
AU - Nyame, Yaw A.
AU - Akdogan, Bulent
AU - Malkoc, Ercan
AU - Gao, Tianming
AU - Altan, Mesut
AU - Citamak, Burak
AU - Mammadov, Emin
AU - Dursun, Furkan
AU - Greene, Daniel J.
AU - Senkul, Temucin
AU - Ates, Ferhat
AU - Ozen, Haluk
AU - Stephen Jones, J.
N1 - Publisher Copyright:
© 2016, Springer Science+Business Media Dordrecht.
PY - 2016/10/1
Y1 - 2016/10/1
N2 - Purpose: The utility of a nomogram is based on the patient population it is designed for—and their inherent properties and biases. Our aim was to demonstrate the variability in predictive model accuracy and utility between different populations. Methods: Our model is based on 761 men who underwent initial TRUS biopsy at a single institution in Turkey. Patients were included if they had at least 10 cores on biopsy and PSA level <20 ng/ml. Multivariable logistic regression models were used to develop a new nomogram. External validity was tested with two different cohorts one from another institution in Turkey (N = 136) and cohort from USA (N = 2242). Results: Prostate cancer (PCa) and high-grade PCa was diagnosed in 249/761 (32.7 %) and 101/761 (13.3 %) patients from Ankara, Turkey, respectively. Predictors of PCa were age (p < 0.0001, OR 2.11), PSA (p = 0.044, OR 1.44), PV (p < 0.0001, OR 0.38), %fPSA (p = 0.016, OR 0.72), and abnormal DRE (p < 0.0001, OR 2.05). The predictive accuracy (c-index) of our nomogram was 73 %. C-indices of 71 and 70 % were recorded in external validation cohorts from Turkey and the USA, respectively. Virtually ideal calibration was recorded for the internal validated predictive model, and good calibration was recorded when applied to the Istanbul cohort. However, the model/nomogram underestimates PCa risk in the US cohort. Conclusion: This is the first nomogram predicting the risk of PCa at initial biopsy in a Turkish population and provides a good risk estimation tool with good predictive accuracy and calibration in the Turkish populations. However, our study demonstrates the poor transferability of predictive tools to widely different populations.
AB - Purpose: The utility of a nomogram is based on the patient population it is designed for—and their inherent properties and biases. Our aim was to demonstrate the variability in predictive model accuracy and utility between different populations. Methods: Our model is based on 761 men who underwent initial TRUS biopsy at a single institution in Turkey. Patients were included if they had at least 10 cores on biopsy and PSA level <20 ng/ml. Multivariable logistic regression models were used to develop a new nomogram. External validity was tested with two different cohorts one from another institution in Turkey (N = 136) and cohort from USA (N = 2242). Results: Prostate cancer (PCa) and high-grade PCa was diagnosed in 249/761 (32.7 %) and 101/761 (13.3 %) patients from Ankara, Turkey, respectively. Predictors of PCa were age (p < 0.0001, OR 2.11), PSA (p = 0.044, OR 1.44), PV (p < 0.0001, OR 0.38), %fPSA (p = 0.016, OR 0.72), and abnormal DRE (p < 0.0001, OR 2.05). The predictive accuracy (c-index) of our nomogram was 73 %. C-indices of 71 and 70 % were recorded in external validation cohorts from Turkey and the USA, respectively. Virtually ideal calibration was recorded for the internal validated predictive model, and good calibration was recorded when applied to the Istanbul cohort. However, the model/nomogram underestimates PCa risk in the US cohort. Conclusion: This is the first nomogram predicting the risk of PCa at initial biopsy in a Turkish population and provides a good risk estimation tool with good predictive accuracy and calibration in the Turkish populations. However, our study demonstrates the poor transferability of predictive tools to widely different populations.
KW - Nomogram
KW - Prostate biopsy
KW - Prostate cancer
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U2 - 10.1007/s11255-016-1328-6
DO - 10.1007/s11255-016-1328-6
M3 - Article
C2 - 27236298
AN - SCOPUS:84970954399
SN - 0301-1623
VL - 48
SP - 1623
EP - 1629
JO - International Urology and Nephrology
JF - International Urology and Nephrology
IS - 10
ER -