Dealing with Differences: Different populations, data sources and countries in HTA modelling

__Abstract__ At its heart, health technology assessment (HTA) is very simple. It compares two or more alternative courses of action, often pharmaceutical interventions, in terms of both their costs and health outcomes.1 One of the interventions will have better health outcomes, for example fewer number of exacerbations, longer survival or a better quality of life. This usually comes at an extra cost, often in the way of a higher price for the intervention. HTA makes this exchange between costs and effects explicit. The idea that costs are an important element to take into account, does not come naturally to many health care workers. Doctors, nurses, and other health care workers do everything they can to help patients improve their lives. The interventions these patients need are provided in a large part by companies developing and producing the necessary drugs and devices. Health care scientists and epidemiologists try to make sense of what constitutes health, what illness is and how disease is spread. Their focus is purely on the patient: what does he or she need? Choices between treatment options are usually a consideration between availability, possible side effects, and patient characteristics. If a new medication comes on the market, doctors are often eager to treat patients with this newest treatment option. With the focus on the patient in front of them, health care workers usually do not look beyond the operating room or treatment room. An oncologist wants to treat all patients to the best of his or her ability, no matter the costs of the intervention. Budgetary constraints are not, and should not, be part of the decision making process of a health care worker when dealing with an individual patient. Cost considerations should be taken into account at a more aggregate level in the clinical guidelines, written by their organizations. In this way, HTA separates health care workers from these concerns in their daily practice, which are in the public and political domain