[Current challenges for scientific research in geriatrics].

Conducting medical research on geriatric patients differs essentially from conducting research on other types of patients. Recruitment and selection of research subjects are difficult, primarily because many geriatric patients will be judged as incapable to consent to participate in scientific research. Moreover, the frailty of geriatric patients requires research instruments that do not trouble subjects too much and research should be aimed at identifying causes of change in functional performances and quality of life. Large randomized controlled clinical trials are very hard to perform in geriatrics, although this research design is considered the most valuable. Therefore, individual treatment decisions generally cannot be evidence based because of a lack of controlled geriatric research or because of uncertainties in individualizing available evidence. In this paper three research designs will be discussed that may be helpful in bridging the gap between evidence and patient care: qualitative research methods, longitudinal research to quantify change in time and interindividual differences in chronic disease, and single patient research aimed at evidencing pharmacotherapeutic decisions in individual elderly patients. These research designs are not new, but they are undervalued and sparsely used. Qualitative research can clarify differences in patients' treatment preferences and motivation and their consequences. Cohort-studies of geriatric patients can show the effects of complex and long lasting medical histories on current treatment options. Single patient research can replace non-systematic trial and error by randomized controlled trials per patient.