Irani J
Service d'Urologie de l'Hôpital La Milétrie, Université Poitiers, CHU Poitiers, France.
Prog Urol. 2008 Apr;18 Suppl 3:S44-6. doi: 10.1016/S1166-7087(08)70513-X.
The aim of the PCPT trial was to compare the incidence of prostate cancer in men treated with finasteride or placebo. The study protocol contains some methodological difficulties. Solutions were adopted designed to minimise damaging bias which could have incorrectly suggested that finasteride was beneficial, or masked a benefit of the drug. As finastéride reduced PSA by an average of 50% the PSA values were interpreted against a new threshold to provide as many biopsies in the finasteride arm as in the placebo arm. In view of the reduction in gland volume, the biopsy protocol was modified to prioritise lateral peripheral cores. Patient adherence to treatment in the finasteride arm and contamination of the placebo arm by people taking finasteride retrospectively after randomisation were taken into account. The increase in sensitivity of rectal examination and in the number of prostatic resections in the placebo arm were also two sources of bias in favour of finasteride. The different envisaged sources of bias were analysed and plans were adopted to manage these wherever possible. Analysis of the sources of bias led to the conclusion that systematic end of trial biopsies constituted the most robust end point.
前列腺癌预防试验（PCPT）的目的是比较接受非那雄胺或安慰剂治疗的男性中前列腺癌的发病率。该研究方案存在一些方法学上的困难。已采取解决方案，旨在尽量减少可能错误地表明非那雄胺有益或掩盖该药物益处的有害偏倚。由于非那雄胺使前列腺特异抗原（PSA）平均降低了50%，因此根据新的阈值对PSA值进行解读，以便在非那雄胺组和安慰剂组进行同样多的活检。鉴于腺体体积减小，活检方案进行了修改，将外周侧叶活检样本作为优先选择。考虑到非那雄胺组患者的治疗依从性以及随机分组后服用非那雄胺的人对安慰剂组的污染情况。安慰剂组直肠指检敏感性的增加以及前列腺切除术数量的增加也是有利于非那雄胺的两个偏倚来源。对不同的潜在偏倚来源进行了分析，并尽可能采取计划来处理这些问题。对偏倚来源的分析得出结论，系统性的试验结束时活检构成了最可靠的终点。
