Clemens J D, Horwitz R I
Biomed Pharmacother. 1984;38(9-10):440-3.
Longitudinal studies of therapy are unparalleled in their ability to ensure scientifically cogent results by clearly separating cause (therapy) from effect (therapeutic outcome), by allowing incorporation of duration of follow-up into the assessment of comparative outcomes, and by permitting the use of safeguards against non-concurrent therapies, unequal prognostic susceptibilities, unequal therapeutic performance, and unequal detection of outcomes. The price of these advantages includes the reduced ability of longitudinal studies to evaluate therapies whose outcomes occur rarely or with long latencies, as well as the specific logistic, ethical, and design problems that limit the ability of clinical trials to answer many of the therapeutic questions which are important to clinical practice. The implications of these limitations are that longitudinal evaluations may not be suitable for addressing many therapeutic issues--particularly those involving preventive therapies--and that even when longitudinal studies are suitable, randomized trials may not be logistically feasible or ethically permissible to answer every clinically important question. One of the important challenges for research in this area is to develop alternative methods for assessing therapeutic effectiveness.
治疗的纵向研究在确保科学可靠结果方面具有无与伦比的能力，这体现在通过清晰地将原因（治疗）与效果（治疗结果）区分开来，通过将随访时间纳入比较结果的评估中，以及通过采取防范措施以应对非同期治疗、不等的预后易感性、不等的治疗表现和不等的结果检测。这些优势的代价包括纵向研究评估那些结果很少出现或潜伏期很长的治疗方法的能力降低，以及特定的后勤、伦理和设计问题，这些问题限制了临床试验回答许多对临床实践很重要的治疗问题的能力。这些局限性的影响在于纵向评估可能不适用于解决许多治疗问题——特别是那些涉及预防性治疗的问题——而且即使纵向研究适用，随机试验在后勤上可能不可行或在伦理上不允许回答每一个临床重要问题。该领域研究的一个重要挑战是开发评估治疗效果的替代方法。
