Regional Health Authority of Umbria, Perugia, Italy.
Trials. 2011 Feb 28;12:58. doi: 10.1186/1745-6215-12-58.
Randomized controlled trials (RCTs) that use the modified intention-to-treat (mITT) approach are increasingly being published. Such trials have a preponderance of post-randomization exclusions, industry sponsorship, and favourable findings, and little is known whether in terms of these items mITT trials are different with respect to trials that report a standard intention-to-treat.
To determine differences in the methodological quality, sponsorship, authors' conflicts of interest, and findings among trials with different "types" of intention-to-treat, we undertook a cross-sectional study of RCTs published in 2006 in three general medical journals (the Journal of the American Medical Association, the New England Journal of Medicine and the Lancet) and three specialty journals (Antimicrobial Agents and Chemotherapy, the American Heart Journal and the Journal of Clinical Oncology). Trials were categorized based on the "type" of intention-to-treat reporting as follows: ITT, trials reporting the use of standard ITT approach; mITT, trials reporting the use of a "modified intention-to-treat" approach; and "no ITT", trials not reporting the use of any intention-to-treat approach. Two pairs of reviewers independently extracted the data in duplicate. The strength of the associations between the "type" of intention-to-treat reporting and the quality of reporting (sample size calculation, flow-chart, lost to follow-up), the methodological quality of the trials (sequence generation, allocation concealment, and blinding), the funding source, and the findings was determined. Odds ratios (OR) were calculated with 95% confidence intervals (CI).
Of the 367 RCTs included, 197 were classified as ITT, 56 as mITT, and 114 as "no ITT" trials. The quality of reporting and the methodological quality of the mITT trials were similar to those of the ITT trials; however, the mITT trials were more likely to report post-randomization exclusions (adjusted OR 3.43 [95%CI, 1.70 to 6.95]; P < 0.001). We found a strong association between trials classified as mITT and for-profit agency sponsorship (adjusted OR 7.41 [95%CI, 3.14 to 17.48]; P < .001) as well as the presence of authors' conflicts of interest (adjusted OR 5.14 [95%CI, 2.12 to 12.48]; P < .001). There was no association between mITT reporting and favourable results; in general, however, trials with for-profit agency sponsorship were significantly associated with favourable results (adjusted OR 2.30; [95%CI, 1.28 to 4.16]; P = 0.006).
We found that the mITT trials were significantly more likely to perform post-randomization exclusions and were strongly associated with industry funding and authors' conflicts of interest.
越来越多的随机对照试验（RCTs）采用改良意向治疗（mITT）方法进行发表。这些试验具有大量的随机后排除、行业赞助和有利的结果，而对于 mITT 试验与报告标准意向治疗的试验在这些项目方面是否存在差异，我们知之甚少。
为了确定不同“意向治疗类型”的 RCTs 在方法学质量、赞助、作者利益冲突和研究结果方面的差异，我们对 2006 年在三种普通医学期刊（《美国医学会杂志》、《新英格兰医学杂志》和《柳叶刀》）和三种专业期刊（《抗菌药物与化疗》、《美国心脏杂志》和《临床肿瘤学杂志》）上发表的 RCTs 进行了横断面研究。根据意向治疗报告的“类型”对试验进行分类如下：ITT，报告使用标准意向治疗方法的试验；mITT，报告使用“改良意向治疗”方法的试验；以及“无意向治疗”，未报告使用任何意向治疗方法的试验。两位审稿人独立地重复提取数据。确定意向治疗报告的“类型”与报告质量（样本量计算、流程图、失访）、试验的方法学质量（随机序列生成、分配隐藏和盲法）、资金来源和研究结果之间的关联强度。使用 95%置信区间（CI）计算比值比（OR）。
在纳入的 367 项 RCTs 中，197 项被归类为 ITT 试验，56 项为 mITT 试验，114 项为“无 ITT”试验。mITT 试验的报告质量和方法学质量与 ITT 试验相似；然而，mITT 试验更有可能报告随机后排除（调整后的 OR 3.43 [95%CI，1.70 至 6.95]；P<0.001）。我们发现，将试验归类为 mITT 与营利性机构的赞助（调整后的 OR 7.41 [95%CI，3.14 至 17.48]；P<0.001）以及作者利益冲突（调整后的 OR 5.14 [95%CI，2.12 至 12.48]；P<0.001）之间存在很强的关联。mITT 报告与有利结果之间没有关联；然而，一般来说，营利性机构赞助的试验与有利结果显著相关（调整后的 OR 2.30；[95%CI，1.28 至 4.16]；P=0.006）。
我们发现，mITT 试验更有可能进行随机后排除，并且与行业资助和作者利益冲突密切相关。
