Estimating the number needed to treat from continuous outcomes in randomised controlled trials: methodological challenges and worked example using data from the UK Back Pain Exercise and Manipulation (BEAM) trial
Estimating the number needed to treat from continuous outcomes in randomised controlled trials: methodological challenges and worked example using data from the UK Back Pain Exercise and Manipulation (BEAM) trial
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DOI：
10.1186/1471-2288-9-35
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发表时间：
2009-06-11
影响因子：
4
通讯作者：
Underwood, Martin
中科院分区：
文献类型：
--
作者：
Froud, Robert;Eldridge, Sandra;Underwood, Martin
背景：报告需要治疗的人数（NNT）提高了试验结果的可解释性。不寻常的是，连续的结果被转换为对治疗有反应的个体的数量（即，那些达到特定变化阈值的人）;预防恶化的情况很少被考虑。我们考虑如何需要治疗的数字可以从连续的结果，说明了一个工作的例子显示的方法和challenges.Methods：我们使用的数据从英国BEAM试验（n = 1,334）的物理治疗背痛，最初报告显示，充其量，小到中等的好处。参与者被随机分配接受一般实践中的“最佳护理”，比较治疗或三种手动和/或运动治疗之一：“最佳护理”加操作，运动或操作后运动。我们使用已建立的Roland-Morris残疾问卷评分在3个月和12个月时改善的共识阈值，以获得改善和获益的NNT（获得的改善+防止的恶化）。三个月时，NNT估计值为5.1（95% CI 3.4至10.7）至9.0（5.0至45.5），5.0（3.4至9.8）至5.4（3.8至9.9）的操作，和3.3（2.5至4.9）至4.8（3.5至7.8）的操作后运动。相应的组间平均差异在罗兰-莫里斯残疾问卷分别为1.6（0.8至2.3），1.4（0.6至2.1），和1.9（1.2至2.6）points.Conclusion：相比之下，小的平均差异最初报道，NNT是小的，可能是有吸引力的临床医生，患者和购买者。NNT可以帮助解释使用连续结局的试验结果。在可能的情况下，这些数据应与平均差异一起报告。在计算一些连续结果的NNT方面仍然存在挑战。试验注册：英国BEAM试验注册：ISRCTN 32683578。
Background: Reporting numbers needed to treat (NNT) improves interpretability of trial results. It is unusual that continuous outcomes are converted to numbers of individual responders to treatment (i.e., those who reach a particular threshold of change); and deteriorations prevented are only rarely considered. We consider how numbers needed to treat can be derived from continuous outcomes; illustrated with a worked example showing the methods and challenges.Methods: We used data from the UK BEAM trial (n = 1,334) of physical treatments for back pain; originally reported as showing, at best, small to moderate benefits. Participants were randomised to receive 'best care' in general practice, the comparator treatment, or one of three manual and/or exercise treatments: 'best care' plus manipulation, exercise, or manipulation followed by exercise. We used established consensus thresholds for improvement in Roland-Morris disability questionnaire scores at three and twelve months to derive NNTs for improvements and for benefits (improvements gained+deteriorations prevented).Results: At three months, NNT estimates ranged from 5.1 (95% CI 3.4 to 10.7) to 9.0 (5.0 to 45.5) for exercise, 5.0 (3.4 to 9.8) to 5.4 (3.8 to 9.9) for manipulation, and 3.3 (2.5 to 4.9) to 4.8 (3.5 to 7.8) for manipulation followed by exercise. Corresponding between-group mean differences in the Roland-Morris disability questionnaire were 1.6 (0.8 to 2.3), 1.4 (0.6 to 2.1), and 1.9 (1.2 to 2.6) points.Conclusion: In contrast to small mean differences originally reported, NNTs were small and could be attractive to clinicians, patients, and purchasers. NNTs can aid the interpretation of results of trials using continuous outcomes. Where possible, these should be reported alongside mean differences. Challenges remain in calculating NNTs for some continuous outcomes.Trial Registration: UK BEAM trial registration: ISRCTN32683578.