In 1899, Charles H. Duell, Commissioner of the U.S. Office of Patents, urged President McKinley to abolish the Patent Office by saying, “Everything that can be invented has been invented.” Fortunately for the health care industry, there have been more significant “medical inventions” in the 89 years following Duell's utterance than in all of recorded history preceding it.

There is now a crisis in medical technology, and it has not been caused by a lack of ideas from innovative clinicians, inventors, and scientists. Instead, it is a result of sincere, but often spasmodic, efforts to control health care costs, which in the minds of many observers threaten the national economy, if not the country's survival.

This article describes criteria used by several organizations to select technologies for assessment and the factors that are common to most lists of criteria. It presents a framework or model (called TAPSS) that relates the most important factors. The model can be used to estimate the expected impact of an assessment on health and economic outcomes for a population. It incorporates information on such factors as the health and economic importance of the disease addressed by the technology, the expected impact of the technology on health and economic outcomes, variations in the technology's current use, and factors affecting the production and reception of an assessment. The article includes an example of an application of the method—screening for maple syrup urine disease.

The use of new therapeutic and diagnostic technologies has become commonplace in modern medical practice. To avoid both clinical disappointment and the waste of money, health, and lives, the introduction of these technologies will have to be based on evidence that these technologies will do more good than harm. The evidence supporting their use should be derived using research methods designed to deal with placebo effects, confounders, and biases. Some of these methods, and the rationale for their use, are discussed in this article. Although the value of evidence derived from randomized controlled trials is stressed, the importance of reviewing critically the methodological details of such trials and interpreting their results with caution is emphasized. The benefits and risks of relying on case-control and cohort studies are reviewed.

Technology assessment involves application of the scientific method to the practice of medicine. Finding all of the assessment reports in a given field is not an easy task. Proper evaluation of those assessments requires the conduct of a prospective experiment in which the sources and results are blinded when the choice is made of papers to exclude and to include, and the process should be carried in duplicate. There are several available data bases for carrying out the search, but because of problems they should be supplemented by reference to the bibliographies of pertinent published articles. Clinical trials included in meta-analyses should be graded by quality and thus facilitate sensitivity analyses. Attention must be paid to the possibility of publication bias. Finally, the advent of meta-analysis makes it desirable to begin randomized controlled trials in areas of uncertainty, even when there is no possibility that individual investigators will encounter enough patients to draw valid conclusions.

Frequently, health care decisions must be made before compelling and unequivocal evidence is available about the benefits, risks, and costs of a proposed new health technology. It is common for decision makers to seek the advice and opinions of experts to supplement the available evidence. This article reviews some of the methods used or recommended for eliciting the opinions of experts about uncertain events and for combining these opinions with those of others and with available empirical evidence.

Utilities and quality-adjusted life years (QALYs) are reviewed, with particular focus on their use in technology assessment. This article provides a broad overview and perspective on these two techniques and their interrelationship, with reference to other sources for details of implementation. The historical development, assumptions, strengths/weaknesses, and applications of each are summarized.

Utilities are specifically designed for individual decision-making under uncertainty, but, with additional assumptions, utilities can be aggregated across individuals to provide a group utility function. QALYs are designed to aggregate in a single summary measure the total health improvement for a group of individuals, capturing improvements from impacts on both quantity of life and quality of life– with quality of life broadly defined. Utilities can be used as the quality-adjustment weights for QALYs; they are particularly appropriate for that purpose, and this combination provides a powerful and highly useful variation on cost-effectiveness analysis known as cost-utility analysis.

Genetic diagnostic techniques increasingly permit the detection of predisposition to illness long before the onset of the disease process itself. Medicine is on the verge of becoming a predictive science as well as a diagnostic and therapeutic one. Genetic diagnosis could have profound effects on many aspects of our health care system, including the prestige and effectiveness of preventive medicine, the competitive behavior of health care organizations and insurance companies, access to private health insurance, the ability of primary care physicians to serve as gatekeepers, and other matters. This article examines the range of potential effects of the new genetic diagnostics on the organization and financing of health care. For purposes of illustration the authors examine in detail the possible consequences of genetic tests for predisposition to two diseases: Reye's Syndrome and lung cancer in smokers.

Chorionic villus sampling (CVS), a new technique for prenatally diagnosing chromosomal and genetic disorders, may soon replace amniocentesis. This procedure, performed by inserting a catheter through the pregnant woman's cervix or through the abdomen and removing cells from the placenta, has the advantages of being available earlier in the pregnancy than amniocentesis (at 9 to 11 weeks gestational age) and of yielding results in a shorter time. Although the medical aspects of the procedure are being investigated, its psychosocial and policy implications have not been studied systematically. These issues include the subjective assessment of risk that prompts women to choose or to reject CVS, the implications of earlier diagnosis for feelings about abortion, the potential of negative findings (i.e., the absence of the designated disorder) for well-being during the remainder of the pregnancy, the ramifications of first trimester identification of fetal sex, equity of access to prenatal diagnosis, and the possible over- utilization of these procedures. Drawing on previous research regarding amniocentesis and more recent research concerning CVS, this article discusses the potential implications of CVS.

The differences in survival rates of colon cancer patients between hospital districts were used as an indicator of equity in cancer treatment in Finland. The merits of two different assessment methods were evaluated. The large variation was mainly due to confounding by age and the extent of the disease and to random variation.

Review of a large data base on 76 patients who had suffered head injuries and whose metabolic changes were being studied demonstrated the variability of their neurological courses and the importance of considering confounding factors in the analysis of such a group. It was apparent that many such patients continue to change neurologically and functionally for long periods of time, and that their ultimate outcome cannot be determined for at least 1 year. The study demonstrates the inherent complexity of a group of patients with head injuries and the need to use sophisticated statistical tools and a computer to demonstrate whether apparent trends are statistically valid in light of confounding factors and variabilities. Failure to take this complexity into account seems to be a major factor in many of the ongoing controversies in research on head injuries. A possible solution to the problem of potential biases introduced by lost patients would be to develop a method to use government records to obtain current addresses for patients involved in federally funded research.

Current practices of donor recruitment for medical fertilization procedures are analyzed in the light of Marcel Mauss' essay on the gift in primitive societies. In this perspective, donor policies seem primarily designed to spare infertile recipients the obligation to recognize the donor's contribution to these procedures, thus avoiding the kinship issues that they raise. Questions of meaning concerning donation, social recognition of the donor's role, and clarification of the relational issues underlying fertilization procedures are nevertheless essential elements in establishing their social legitimacy.

A colorimetric instrument for the noninvasive quantification of hemoglobin, designed using color shades resembling those observed in the conjunctiva, was tested. The instrument's colors are contrasted against the color of the conjunctiva to measure hemoglobin content. Sensitivity, specificity, negative predictive value, and false-negative value were estimated to test the instrument's accuracy; kappa coefficients were used to estimate inter- and intraobserver variability. Physician field evaluations of conjunctiva color for the screening of anemia, reported in the literature, have had sensitivities and specificities as high as 70%. Readings with the instrument demonstrated a 63% sensitivity, 72% specificity, and 38% false negatives for screening hemoglobin values of less than or equal to 13 g/dl. The interobserver kappa coefficients for three pairs of readers were good to excellent for the same hemoglobin screening value. Statistically significant differences were noted, however, between observers during the reliability test. The instrument can be used by unskilled personnel to improve their decision-making about whom to send for futher care or for supplementation with iron.