Feaster Daniel J, Newman Frederick L, Rice Christopher
Clin Psychol Psychother. 2003;10(6):352-360. doi: 10.1003/cpp.382.
The most appropriate amount of psychotherapy to address a particular problem is of interest to clinicians, consumers and those responsible for funding of care. The dose-response relationship has been examined within the context of randomized clinical trials, meta-analysis as well as naturalistic studies; however, each of these approaches has limits. Many of these approaches have conceptually blurred two distinct concepts: do participants with different characteristics need different amounts of therapy and do otherwise equal participants show different outcomes when given different levels of (a particular type of) therapy? For any study design, if the experimenter does not determine the duration of therapy, then the length of therapy is said to be endogenous. This endogeneity can bias any attempt to untangle the answer to these two questions. An extension of the biasing effect of this endogeneity involves the choice of times to assess outcome; if outcome assessment depends on when therapy is terminated (rather than exogenously chosen) then estimates of the trajectory of outcome may be biased. Design considerations to minimize this effect are discussed.
临床医生、患者以及负责护理资金的人员都对解决特定问题所需的心理治疗的最适当剂量感兴趣。已经在随机临床试验、荟萃分析以及自然主义研究的背景下研究了剂量反应关系；然而，这些方法中的每一种都有局限性。这些方法中的许多在概念上模糊了两个不同的概念：具有不同特征的参与者是否需要不同剂量的治疗，以及在给予不同水平（特定类型）的治疗时，其他条件相同的参与者是否会表现出不同的结果？对于任何研究设计，如果实验者没有确定治疗的持续时间，那么治疗的长度就被认为是内生的。这种内生性会使任何试图理清这两个问题答案的尝试产生偏差。这种内生性的偏差效应的一个延伸涉及结果评估时间的选择；如果结果评估取决于治疗何时终止（而不是外部选择），那么结果轨迹的估计可能会有偏差。本文讨论了将这种效应降至最低的设计考虑因素。
