Department of Urology, Erasmus Medical Center, Rotterdam, The Netherlands.
Eur J Cancer. 2011 Apr;47(6):903-9. doi: 10.1016/j.ejca.2010.11.012. Epub 2010 Dec 14.
Prediction models need external validation to assess their value beyond the setting where the model was derived from.
To assess the external validity of the European Randomized study of Screening for Prostate Cancer (ERSPC) risk calculator (www.prostatecancer-riskcalculator.com) for the probability of having a positive prostate biopsy (P(posb)).
DESIGN, SETTING AND PARTICIPANTS: The ERSPC risk calculator was based on data of the initial screening round of the ERSPC section Rotterdam and validated in 1825 and 531 men biopsied at the initial screening round in the Finnish and Swedish sections of the ERSPC respectively. P(posb) was calculated using serum prostate specific antigen (PSA), outcome of digital rectal examination (DRE), transrectal ultrasound and ultrasound assessed prostate volume.
The external validity was assessed for the presence of cancer at biopsy by calibration (agreement between observed and predicted outcomes), discrimination (separation of those with and without cancer), and decision curves (for clinical usefulness).
Prostate cancer was detected in 469 men (26%) of the Finnish cohort and in 124 men (23%) of the Swedish cohort. Systematic miscalibration was present in both cohorts (mean predicted probability 34% versus 26% observed, and 29% versus 23% observed, both p<0.001). The areas under the curves were 0.76 and 0.78, and substantially lower for the model with PSA only (0.64 and 0.68 respectively). The model proved clinically useful for any decision threshold compared with a model with PSA only, PSA and DRE, or biopsying all men. A limitation is that the model is based on sextant biopsies results.
The ERSPC risk calculator discriminated well between those with and without prostate cancer among initially screened men, but overestimated the risk of a positive biopsy. Further research is necessary to assess the performance and applicability of the ERSPC risk calculator when a clinical setting is considered rather than a screening setting.
预测模型需要外部验证，以评估其在模型推导之外的环境中的价值。
评估欧洲前列腺癌筛查随机研究（ERSPC）风险计算器（www.prostatecancer-riskcalculator.com）用于预测前列腺活检阳性概率（P(posb)）的外部有效性。
设计、地点和参与者：ERSPC 风险计算器基于 ERSPC 鹿特丹部分初始筛查轮的数据，并在芬兰和瑞典部分的 ERSPC 初始筛查轮中分别对 1825 名和 531 名接受活检的男性进行了验证。使用血清前列腺特异性抗原（PSA）、数字直肠检查（DRE）结果、经直肠超声和超声评估的前列腺体积计算 P(posb)。
通过校准（观察结果与预测结果的一致性）、区分（有癌与无癌的区分）和决策曲线（用于临床有用性）评估活检时癌症存在的外部有效性。
芬兰队列中有 469 名男性（26%）和瑞典队列中有 124 名男性（23%）检出前列腺癌。两个队列均存在系统的校准偏差（平均预测概率为 34%，观察值为 26%，29%，观察值为 23%，均<0.001）。曲线下面积分别为 0.76 和 0.78，而仅 PSA 的模型分别为 0.64 和 0.68，显著降低。与仅 PSA、PSA 和 DRE 或对所有男性进行活检的模型相比，该模型在任何决策阈值下均具有临床实用性。局限性在于该模型基于六分区活检结果。
ERSPC 风险计算器在最初筛查的男性中能够很好地区分有癌和无癌患者，但高估了阳性活检的风险。需要进一步研究，以评估 ERSPC 风险计算器在考虑临床环境而非筛查环境时的性能和适用性。
