Screening without evidence of efficacy
http://www.100md.com
《英国医生杂志》
EDITOR—Law's editorial on screening without evidence of efficacy prompted a predictably substantial number of responses that were, perhaps not so predictably, mostly united in their agreement with his objections to advocating screening of unproved value.1 He concludes: "For a new drug a rigorous set of experimental data must be presented before it is licensed for use, and until it is licensed patients cannot obtain it. The same rigour should apply to medical screening."
Most of the responses questioned the value of screening and threw its potential cost to the public purse into the equation; some highlighted that it was harmful. One correspondent explained what happens if health authorities advocate screening of unproved value, as illustrated by primary prevention of cardiovascular disease in the United Kingdom, where political and financial imperatives to screen and treat have been powerful inducements to change routine practice.
Two correspondents argued passionately that screening (in the form of breast awareness and testing for prostate specific antigen) was a very good thing indeed. Another took a level view and cited systematic reviews to support his own opinion, that the benefits of screening cannot be determined.
Others questioned the drug trial analogy. Randomised controlled trials are appropriate for testing the safety and efficacy of drugs, but they are not appropriate for screening. Drug discovery and development processes are subject to intellectual property laws and governmental regulation. If a pharmaceutical company shows that a new drug is safe and efficacious in a particular condition its investment on research and development costs may well be returned with patent protection and exclusivity rights for several years. No patents exist for screening programmes, and the funding for a thorough evaluation of their risk and benefits would therefore have to come from the public purse.
Another correspondent cites a case in US law as an example of a worst case scenario and asks for rigorous experimental data to be presented before a test is licensed, with people always being informed about the reasons why a test is not available. This would balance claims made by manufacturers' advertisements, which are often based on preliminary studies.
The complexity of the issue is illustrated particularly clearly in a numerical example that an informed decision about testing for prostate specific antigen might be based on. The author reminds us that it is perfectly reasonable to weigh up the pros and cons of screening and conclude that it is a good thing but that advocating a screening programme to others implies an unequivocal benefit.
Most of the responses questioned the value of screening and threw its potential cost to the public purse into the equation; some highlighted that it was harmful. One correspondent explained what happens if health authorities advocate screening of unproved value, as illustrated by primary prevention of cardiovascular disease in the United Kingdom, where political and financial imperatives to screen and treat have been powerful inducements to change routine practice.
Two correspondents argued passionately that screening (in the form of breast awareness and testing for prostate specific antigen) was a very good thing indeed. Another took a level view and cited systematic reviews to support his own opinion, that the benefits of screening cannot be determined.
Others questioned the drug trial analogy. Randomised controlled trials are appropriate for testing the safety and efficacy of drugs, but they are not appropriate for screening. Drug discovery and development processes are subject to intellectual property laws and governmental regulation. If a pharmaceutical company shows that a new drug is safe and efficacious in a particular condition its investment on research and development costs may well be returned with patent protection and exclusivity rights for several years. No patents exist for screening programmes, and the funding for a thorough evaluation of their risk and benefits would therefore have to come from the public purse.
Another correspondent cites a case in US law as an example of a worst case scenario and asks for rigorous experimental data to be presented before a test is licensed, with people always being informed about the reasons why a test is not available. This would balance claims made by manufacturers' advertisements, which are often based on preliminary studies.
The complexity of the issue is illustrated particularly clearly in a numerical example that an informed decision about testing for prostate specific antigen might be based on. The author reminds us that it is perfectly reasonable to weigh up the pros and cons of screening and conclude that it is a good thing but that advocating a screening programme to others implies an unequivocal benefit.