Baker H W
Clin Reprod Fertil. 1986 Feb;4(1):13-25.
The majority of men who present with infertility have oligospermia or asthenospermia which renders them subfertile; pregnancies occur at lower than normal rates. Currently available treatments for this group are of uncertain value. This paper outlines an approach to controlled trials to test old and new methods for their ability to improve semen quality and increase pregnancy rates. As well as careful design, the need for control groups and large numbers of subjects is emphasized. Control groups are necessary because pregnancies and apparent or real spontaneous improvements in semen test results occur without treatment. Trials to evaluate differences in pregnancy rates need to be large because pregnancy rates are low and the margin for improvement narrow. Most untreated infertile couples have average pregnancy rates of less than 5% per month, whereas pregnancy rates in the general community average 20% per month. Under these circumstances, small trials with less than 20 pregnancies are unhelpful as they are not sensitive enough to detect less than threefold differences in pregnancy rates between groups. The number of subjects required for a trial can be calculated or determined from tables or graphs. A 50% difference in pregnancy rates in two groups given alternative treatments only has a high chance of being statistically significant if there are hundreds of subjects achieving a total of approximately 200 pregnancies in the trial. Such large trials can only be performed by several centres collaborating.
大多数患有不育症的男性存在少精子症或弱精子症，这使他们生育能力低下；怀孕率低于正常水平。目前针对这一群体的现有治疗方法价值不确定。本文概述了一种进行对照试验的方法，以测试新旧方法改善精液质量和提高怀孕率的能力。除了精心设计外，还强调了设立对照组和大量受试者的必要性。设立对照组是必要的，因为未经治疗也会出现怀孕情况以及精液检测结果明显或实际的自然改善。评估怀孕率差异的试验需要大量样本，因为怀孕率低且改善幅度小。大多数未经治疗的不育夫妇每月平均怀孕率低于5%，而普通人群的怀孕率平均每月为20%。在这种情况下，怀孕次数少于20次的小型试验没有帮助，因为它们不够灵敏，无法检测出两组之间怀孕率小于三倍的差异。试验所需的受试者数量可以通过计算得出，也可以从表格或图表中确定。如果在试验中有数百名受试者总共实现约200次怀孕，那么接受两种替代治疗的两组之间怀孕率50%的差异才有很大机会在统计学上具有显著性。这样的大型试验只能由多个中心合作进行。
