In-vitro fertilization (IVF) is a relatively recent approach to overcoming human fertility problems. This study explored factors in the diffusion of IVF in England and in the Netherlands. Many factors were common to the two countries. Governments in both countries have been passive, apparently wishing to avoid entering a controversial field. Technology assessment has played little part in the diffusion process in these two countries.

Statistical analyses that involve regression methods often encounter data in which some observations have substantial influence. This article presents a nontechnical discussion of influence and of two techniques, based on leaving out each individual observation in turn, for diagnosing influential data. An example illustrates the techniques in an analysis of recurrence rates in endoscopic treatment of bleeding peptic ulcers.

Persistent pulmonary hypertension of the newborn or persistent fetal circulation is a clinical syndrome that is usually apparent within the first 2 days after birth because of the presence of hypoxemia (2;12;19). The syndrome was first described in an abstract by Gersony, Due, and Sinclair (6) in 1969. Two infants were reported who had “RV decompensation, cyanosis and clear lung fields… in the absence of recognizable cardiac, pulmonary, hematologic or CNS disease.” The syndrome has been associated with aspiration of meconium, diaphragmatic hernia, asphyxia, hemorrhage, shock, and maternal infection (4;18). In other cases, there is no clear antecedent event. Despite considerable interest in the problem and a wealth of research related to pulmonary vasoregulation and vascular development in the fetus and newborn, the etiology of the syndrome remains obscure 20 years since its recognition.

The availability and efficacy of recombinant deoxyribonucleic acid yeast-derived hepatitis-B vaccine, at a price much lower than the previously available plasma-derived hepatitis-B vaccines against hepatitis-B virus infections, motivate a new cost-benefit analysis of hepatitis-B vaccination. Spanish data were used to calculate direct and indirect costs of hepatitis-B infection and the costs and benefits of different vaccination strategies in defined risk groups of the Spanish population. A vaccination program will reduce direct expenditures for hepatitis B if the attack rate in the target population is higher than 4.9%. If indirect costs are included, the threshold for cost saving is reduced to 0.9%. The results are sensitive to the price of the vaccine, the duration of protection, assumptions about consequences for quality of life, and to indirect costs.

Cochlear prostheses are beginning to be implanted regularly to restore hearing in profoundly deaf patients, but there is little agreement on the relative merits of the many different designs and rehabilitative procedures. We report on the responses to a technology assessment questionnaire that was sent to 120 researchers and clinicians worldwide who have been at the forefront of research in this field.

Two observations about the ductus arteriosus are established: most normally developed infants will have a patent ductus arteriosus (PDA) at the time of delivery, and most fullterm infants will have anatomic obliteration of the ductus lumen by 3–6 months of age. Studies designed to determine how a PDA contributes to an infant's morbidity or when a PDA becomes a persistently patent ductus arteriosus have been hampered by the lack of consistent diagnostic criteria for defining the condition. Ellison et al. (22) attempted to evaluate several commonly used criteria for diagnosing a large leftto-right shunt through the ductus arteriosus by noting the occurrence of each sign both before and 36–48 hours after surgical ligation. No single criterion sufficed as an indicator of PDA. Certain signs, such as continuous murmur or hyperactive left ventricular impulse, were specific for a PDA, but lacked sensitivity; conversely, M-mode echocardiography and ventilatory support criteria were very sensitive but lacked specificity.

The decision whether to enhance diffusion and to reimburse for the fertility treatment in-vitro fertilization (IVF) was postponed in the Netherlands until the results of a cost-effectiveness analysis were known. IVF appeared to be as cost-effective as its most important alternative, tubal surgery. But policy decisions still were not straightforward, obscuring important social and ethical issues.

Evaluating the use of resources as well as outcomes in cancer therapy is increasingly becoming recognized by both clinicians and others as a legitimate and indeed even desirable activity. While this trend is to be welcomed if it facilitates the efficient use of resources for cancer care, there are dangers in applying estimates of unit costs, in particular average costs to the evaluation of trends in practice in cancer therapies. This article examines the use of appropriate measures of average and marginal cost in the economic evaluation of developments in cancer therapy, taking illustrations from radiotherapy and chemotherapy.

Systemic blood pressure (BP) is the product of cardiac output and total peripheral resistance. Cardiac output is controlled by the heart rate, myocardial contractility, preload, and afterload. Vascular resistance (vascular hindrance × viscosity) is under local autoregulation and general neurohumoral control through sympathetic adrenergic innervation and circulating catecholamines. Sympathetic innovation predominates in organs receivingflowin excess of their metabolic demands (skin, splanchnic organs, kidney), while innervation is poor and autoregulation predominates in the brain and heart. The distribution of blood flow depends on the relative resistances of the organ circulations. During stress (hypoxia, low cardiac output), a raise in adrenergic tone and in circulating catecholamines leads to preferential vasoconstriction in highly innervated organs, so that blood flow is directed to the brain and heart. Catecholamines also control the levels of the vasoconstrictors renin, angiotensin II, and vasopressin. These general principles also apply to the neonate.

Breast cancer is the second leading cause of death by cancer among women in the United States. The total cost of illness for breast cancer has been estimated to be $3.8 billion, of which $1.8 billion represents medical care costs. It has been estimated that breast cancer detected early is considerably less expensive than when the tumor is discovered at a later stage. Mass screening using mammography can improve early detection by as much as 15–35%. Cost-effectiveness studies have estimated that the costs of breast cancer screening range between $13,200 and $28,000 per year of life saved. The cost-effectiveness of breast cancer screening in the 40–49-year-old age group is controversial. Mass screening for breast cancer will probably increase total health care costs, but when all economic costs are included, screening appears to be more cost-effective than not screening.

As those involved in neonatal intensive care are well aware, water and heat balance play a very important role in the well-being of the newborn infant. While some aspects of water and heat balance have been studied extensively, others have been less elucidated. Recent studies have demonstrated that both insensible and sensible water loss depend on the maturity of the infant and that both environmental factors and the activity of the infant can have dramatic effects on both these modes of water loss. As heat loss is affected by the insensible and sensible water loss from the infant, the same factors also have implications for heat loss, but heat loss is also influenced by other factors. The aim of this article is to review some of the knowledge relevant to the fields of water and heat balance in the neonatal period.