Such studies have been inconclusive because of their insufficient size, the use of historical controls, a limited duration of follow-up, and a lack of access to original source data.
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美
- 因病例数有限、使用的对照为既往的资料、随访期限不足以及缺乏对原始资料的最终,所以这些研究的结果不是结论性的。