Assessing Medical Technologies (1985) / Chapter Skim
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4. Effects of Clinical Evaluation on the Diffusion of Medical Technology
4. Effects of Clinical Evaluation on the Diffusion of Medical Technology
Pages 176-210
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From page 176... ...
Following a review of literature about the effect of evaluation on the diffusion of medical technology, the chapter summarizes its principal conclusions and offers a few recommendations. The relation between evaluation and diffusion is part of a larger issue of the contribution of technology assessment to improved health.
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From page 177... ...
The emphasis is on physician practices and on the influence of various forms of clinical evaluation in changing those practices. Primary clinical evaluations could be arranged in a hierarchy according to their freedom from bias, for instance, with the randomized clinical trial (RCT)
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From page 178... ...
cites a number of classic examples, such as the resistance to smallpox vaccination by those who held that improved sanitation was the main cause of a decline in the smallpox rate, disbelief in the manifold consequences of syphilis by those who held to the theory of duality of tuberculosis; and refusal to recognize puerperal fever as a contagious disease by those who subscribed to atmospheric, cosmic, and telluric influences on health. Twentieth century examples include long-delayed acceptance of salicylates in the treatment of rheumatoid ASSESSING MEDICAL TECHNOLOGY arthritis (Goodwin and Goodwin, 1982)
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From page 179... ...
The pattern of practice among colleagues influences the way physicians use available medical technology (Freeborn et al., 1972~. The Decision-Making Process Some medical practice decisions are wholly within the domain of the individual practitioner.
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From page 180... ...
This finding has been reaffirmed in recent studies showing that personal representation by pharmacists or, even more effectively, by other physicians can influence doctors to be more prudent drug prescribers (Avorn and Soumerai, 1983; Schaffner, 1983~. Studies of how doctors learn about new medical practices, based on physician surveys, have found medical journals, discussion with colleagues, and continuing eduASSESSING MEDICAL TECHNOLOGY cation each to be regarded as important sources, with journals most consistently cited as high (Fineberg et al., 1978; Manning and Denson, 1979, 1980; Stross and Harlan, 1981; Market Facts, 1982; Jordan et al., 1983~.
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From page 181... ...
The expanding availability of personal computers in physician homes and offices offers a new medium that can potentially convey evaluative information on new and current medical practices. Of course, the physicians most resistant to changing their medical practices may also be the last ones to install a home computer.
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From page 182... ...
The potential target population is explicitly the denominator in a fraction and is left unspecified in the case of counts. In either case, the interpretation of a study depends on an appropriately deASSESSING MEDICAL TECHNOLOGY fined target population that is either stable over time or is correctly adjusted over time, as, for example, the target pool of patients varies or the number of trained clinicians changes.
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From page 183... ...
With expected behavior 183 as the standard, emphasis is on changes in the pattern of diffusion that can be related to evaluation. A clinical evaluation might affect both the rate of adoption or abandonment of a practice and the extent of its ultimate use.
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From page 184... ...
Do the implications require a change in the use of a medical technology? In efforts to discriminate among the effects of different types of evaluation, are the implications from one type of evaluation different from the implications of others?
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From page 185... ...
185 Evaluation and Physician Behavior All but two of the reviewed studies deal at least in part with the relation between clinical evaluation and the knowledge, beliefs, and decisions of physicians. The kinds of evaluation whose effects are examined in these studies fall into two broad groups: primary evaluations, such as randomized clinical trials, which acquire and present new clinical findings; and synthetic evaluations, such as consensus conferences, which integrate and interpret available primary evidence.
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From page 186... ...
As in the case of diabetic retinopathy, a later study would raise questions about the translation of this RCT into effective clinical practice, in part beASSESSIN(7 MEDICAL TECHNOLOGY cause of inappropriate medication prescribed by physicians and in part because of patient nonadherence to prescribed medication regimens (Wagner, 1981~. The management of hypertension illustrates some of the pitfalls in attempting to draw conclusions about the effects of clinical evaluations on physician awareness and medical practice.
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From page 187... ...
Five clinical practices (internal mammary artery ligation, gastric freezing, treatment of breast cancer, antiplatelet agents for the prevention of recurrent myocardial infarction, and management of mild hypertension) are each examined in 2 papers.
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From page 188... ...
1983 Referral for treatment Senile macular degeneration 8 Fineberg 1979 Artificial lung Respiratory failure 9 Fineberg and Hiatt 1979 Gastric freezing Ulcer disease 10 Finkelstein and Gilbert 1983 Tolbutamide Diabetes mellitus 11 Fisher and Kennedy 1982 Coronary artery bypass Cardiovascular graft surgery disease 12 Fisher and Kennedy 1982 Internal mammary artery Angina pectoris ligation 13 Friedewald and Schoenberger 1982 Drug prescription Mild hypertension 14 Friedewald and Schoenberger 1982 Antiplatelets Cardiovascular disease 15 Friedewald and Schoenberger 1982 Beta-blockers Cardiovascular disease 16 Friedewald and Schoenberger 1982 Lipid-lowering drugs Cardiovascular disease 17 Friedman et al. 1983 Lipid-lowering drugs Cardiovascular disease 18 Haines 1983 Neurosurgery Neurosurgical conditions 19 Market Facts 1982 Lipid-lowering drugs Cardiovascular disease 20 Market Facts 1982 Antiplatelets Cardiovascular disease 21 McPherson and Fox 1977 Treatments Breast cancer 22 Miao 1977 Gastric freezing Ulcer disease 23 Moskowitz et al.
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From page 189... ...
practice over time and thus provide evidence about the relation between RCTs and diffusion of medical technology. This latter group of 10 studies covers seven medical practices: oral hypoglycemics for diabetics (Chalmers, 1974; Warner et al., 1978; Finkelstein and Gilbert, 1983~; referrals for treatment of senile macular degeneration (Combs et al., 1983~; gastric freezing (Fineberg, 1979~; lipid-lowering drugs (Market Facts, 1982; Friedman et al., 1983~; length of hospital stay for myocardial infarction (Chassin, 1983~; coronary artery bypass graft surgery (Fisher and Kennedy, 1982~; and treatment of breast cancer (OTA, 1983~.
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From page 190... ...
Some difficulties in discerning temporal and causal connections between clinical evaluations and changes in medical practice are illustrated by the case of length of hospital stay for myocardial infarction. In this instance of medical decision making, changing patterns of practice, randomized trials, and evidence from nonrandomized studies all overlap in time in a way that defies inferences of causal relations.
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From page 191... ...
It is evident from inspection of Figure 4-4 that many physicians have been discharging patients with myocardial infarction earlier than had yet been demonstrated as safe by randomized trials. Simply because a study fails to demonstrate beyond a reasonable doubt that a clinical trial has influenced the diffusion of a practice does not mean that the clinical trial was not actually influential.
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From page 192... ...
The Coronary Artery Surgery Study enrolled nearly 25,000 patients undergoing angiography at 15 institutions (Fisher and Kennedy, 1982~. The proportion of patients with one-vessel disease who underwent surgery declined from 38 percent in 1974-1975 to 30 percent in 1978-1979, a result consistent with the findings of randomized trials that had appeared in the interim.
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From page 193... ...
Of special interest are studies that compare the influence of randomized and of nonrandomized clinical trials. According to an opinion expressed by the Office of Technology Assessment, randomized clinical 193 trials have been applied to 10 or 20 percent of medical practices (OTA, 1983~.
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From page 194... ...
This ASSESSING MEDICAL TECHNOLOGY study is intended to trace the dissemination of conclusions from NIH consensus conferences into the medical community and to measure changes over time in reliance on practices that have been the subject of a consensus conference. Its results are expected to be available in 1985.
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From page 195... ...
FDA's insistence and reliance on randomized controlled trials in the licensing of new drugs probably constitute the most potent source of influence of RCTs on the diffusion of new medical technology in the United States. Although the FDA approves particular uses of a new drug, physicians are generally free to prescribe a licensed drug as they
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From page 196... ...
Those who are working to improve methods for evaluating medical practices should attend to strengthening the weaker methods, such as case studies and nonrandomized trials, in order to enhance their reliability as guides to clinical action. At present, stronger forms of evaluation, such as controlled trials, are not notably more successful than weaker forms in shaping medical practices.
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From page 197... ...
education of physicians and medical students about evaluation methods, principles of decision making, and the effects of specific clinical practices; (2) innovative methods of communicating the results of clinical evaluations to physicians and other decision makers, including the possible use of electronic media such as home computers and medically oriented cable television stations; (3)
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From page 198... ...
Third-party payers can support demonstration projects to reduce the inappropriate use of clinical practices. APPENDIX 4-A: SUMMARIES OF STUDIES ASSESSING MEDICAL TECHNOLOGY Many of these recommended actions are already under way in some degree, though they need to be extended, reinforced, and coordinated.
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From page 199... ...
ter initially pub- were resolved by a clear nal medicine fished cut clinical trial. Oral hypogly- Marks, unpub- UGDP Published articles, re- Views persistent controver cemic agents fished report views, editorials, sies as disputes over cri in diabetics (1983)
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From page 200... ...
RCTs have been more use apy mitage et al. controlled trials ful than non-RCTs in (1978)
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From page 201... ...
2 controlled trials Medical records of 10-15 years after the first hepatitis (randomization hospitalized pa- definitive study 49% of unspecified) show tients.
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From page 202... ...
on anesthesi- (1978) ology Referrals for treatment of senile macular degeneration Internal mammary artery ligation Combs (1982)
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From page 203... ...
cased by RCTs, Percent of breast cancer patients 1972 1981 Radical mastectomy 50 % Modified radical 30 % 70 % Lumpectomy 3 % 8 % (Remainder) presumably represents simple mastectomy and possibly other treatments.
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From page 204... ...
Majority of physicians remained unaffected by AMIS findings, continuing to prescribe aspirin for patients following myocardial infarction. Many medical mistakes occur because of the absence of proper early evaluation.
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From page 205... ...
Most of those aware of study findings had read about them in professional journals. Studies of Effect of Synthetic Assessments on Clinical Practices Guidelines Leff et al.
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From page 206... ...
Studies of the Effects of Clinical Evaluations and Synthetic Assessments on Regulation and Reimbursement PHS adviso- Center for Analy- Review by PHS Estimates of authors. The PHS through National ries to sis of Health Center for Health Care HCFA Practices (1981)
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From page 207... ...
1982. Overview of randomized clinical trials of lipid intervention for atherosclerotic cardiovascular disease.
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From page 208... ...
1979. Gastric freezing: A study of ASSESSING MEDICAL TECHNOLOGY diffusion of a medical innovation.
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From page 209... ...
1983. The Impact of Randomized Clinical Trials on Health Policy and Medical Practice.
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From page 210... ...
ASSESSING MEDICAL TECHNOLOGY Washington, D.C.: Public Citizen's Health Research Group. Williamson, P
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