• 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
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.
• Their meta-analysis revealed that the overall risk of lung cancer among lifelong non-smoking women was 1.24 times higher when their husbands smoked, as compared to those women whose husbands did not smoke.
• 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 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
让我们来看看 系统评价的真实面目
系统评价的定义
系统评价是一全新的文献综合评价临床研究方 பைடு நூலகம்，其基本过程是以某一具体临床问题为基础，系 统、全面地收集全世界所有已发表或未发表的临床 研究结果，采用临床流行病学严格评价文献的原则 和方法，筛选出符合质量标准的文献，进行定性或 定量合成，去粗取精，去伪存真，得出综合可靠的 结论。同时，随着新的临床研究结果的出现进行及 时的更新。
• 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
系统评价和Meta分析
Systematic Review and Meta-analysis
郑景辉
问题的提出
对上述结果， 是不是难以判断并选择？
用X线进行乳腺癌筛查 Mammography for breast cancer is an established screening method
• 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)
• 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).
Systematic review (SR)
Systematic review (SR)
“A summary of the medical literature that uses explicit methods to perform a thorough literature search and critical appraisal of individual studies and that uses appropriate statistical techniques to combine these valid
• They concluded that “screening for breast cancer with mammography is unjustified”
The US Preventive Services Task Force reviewed the same set of trials