Meta－分析的统计学基础课件.ppt

Meta－分析的统计学基础 王洪源 北京大学公共卫生学院 流行病学与卫生统计学系why_w@ 一、 概 述 用X线进行乳腺癌筛查Mammography for breast cancer is an established screening method Is screening with mammography justifiable? Gotzsche & Olsen [Nordic Cochrane Centre] conducted a systematic review in 2000 and updated it in 2001. They identified 8 large RCTs on this topic, with over 182,000 women randomized The authors found that no trial data were of high quality Two were of medium quality, and the rest were poor quality or flawed. When the results of the two medium quality trials were combined, the risk ratio was 1.00 (95% CI 0.96, 1.05) They concluded that “screening for breast cancer with mammography is unjustified” The US Preventive Services Task Force reviewed the same set of trials Recently, a 2001 Cochrane Collaboration review of the same trials concluded that six of the eight trials were "flawed" or of "poor quality" and that the pooled results from the remaining two better trials did not support a benefit from mammography. The meta-analysis performed for the USPSTF on the most current published data found that the pooled effect size of the combined trials was sizable and statistically significant: the summary relative risk (RR) of breast cancer death among women randomized to screening in seven trials that included women older than 50 was 0.77 (95 percent CI, 0.67-0.89). The USPSTF recommends screening mammography, with or without clinical breast examination, every 1-2 years for women aged 40 and older. 被动吸烟的危害 A topic of great debate and controversy for many years First few epidemiologic studies were published in 1918 Hackshaw et al. conducted a very comprehensive systematic review in 1997 They identified 37 published studies that reported risk of lung cancer among lifelong non-smoking women according to the husband’s smoking status Their meta-analysis revealed that the overall risk of lung cancer among lifelong non-smoking women was 1.24 times higher when their husban