Epidemiology -Principles of Screening_预防医学.pptVIP

* * * * * * * * * The underlying ethical-medical principle of ‘do no harm’ carries additional significance to clinical practice and cancer screening. Because screening takes place in asymptomatic (healthy) individuals, the possibility of causing harm and little benefit to this individual must be considered prior to making the screening decision. The screening decision should be based on the documented effectiveness (i.e., performance characteristics, such as sensitivity) and efficacy (i.e., screening intervention results, such as reduced mortality). As mentioned previously, the risk of the follow up testing must be considered in addition to risks inherent in the screening test itself. Colorectal cancer screening presents a case in point. One of the two recommended screening tests—flexible sigmoidoscopy—is uncomfortable, requires extensive preparation, and carries risk of bowel perforation and heavy bleeding. Those risks are even more substantial for colonoscopy, which is now reimbursed as a CRC screening procedure for Medicare patients. The question becomes more relevant for those who falsely test positive with initial screening and undergo further procedures that are unnecessary, expensive, and with potential for harm. * * Designs for RCTs of Screening Programs Designs for RCTs of Screening Programs Tests of screening programs for hypertension and high cholesterol have used design B primarily. Tests of screening programs for mammography and colorectal cancers have use design A primarily. RCT of a Screening Program: Mammography Mammography has the most direct type of evidence of any cancer screening program yet has been controversial since introduced in the 1960s aimed at early detection of invasive cancer, which is treated by major surgery unlike screening for colon cancer and cervical cancer, which is aimed at detecting and removing pre-cancerous lesions to prevent invasive cancer Breast Cancer Screening Program in the Health Insurance Plan (HIP) of New