方法采用分组对照研究的方法，检查组与对照组对结核菌素纯蛋白衍化物（PPD）试验的反应情况。
METHODS In a cross-sectional survey, we studied purified protein derivative(PPD) test in exposure group and control group.
这项英国研究把107位病人随机选择分组，对照组的治疗只有卧床休息，治疗组在卧床休息之外还每天注射链霉素。
The British study randomly assigned 107 patients either to a control group that received only bed rest or to a treatment group that received daily injections of streptomycin in addition to bed rest.
设计：随机分组、实验对照、前瞻性研究。
DESIGN: Randomly grouping, experimental control and prospective study.
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