文中介绍了筛检研究中确定筛检间隔的病例对照研究设计方法。应用此方法从前瞻性肝癌筛检资料中进行再抽样组成１：４匹配的病例对照，考察了阴性筛检后不同时间对肝癌死亡和发病的保护效应。结果表明在调整了肝病史和肝癌家族史后，这种保护效应在肝癌高危人群中自阴性筛检后一年半左右基本消失，由此建议其筛检的时间间隔以一年左右为宜。 The case-control study design method for determining the screening interval in screening studies was introduced. This method was used for re-sampling from a prospective liver cancer screening data to form a 1:4 matched case-control, and to examine the protective effect of negative screening on the death and pathogenesis of hepatocellular carcinoma at different times. The results showed that after adjusting the history of liver disease and the family history of liver cancer, this protective effect basically disappeared about one and a half years after the screening for self-negative people at high risk of liver cancer, suggesting that the time interval for screening should be about one year.