Fifty years' development and future perspectives of psychiatric register research.

OBJECTIVE: This article illustrates the development of psychiatric register research and discusses the strengths, limitations, and possible directions for future activities.
METHOD: Examples illustrating the development from the post-World War II introduction of psychiatric register research until today are selected.
RESULTS: The strengths of register research are seen especially within health service. Until recently, when starting linking registers to biobanks, register research had limited value in cause-seeking. Register research benefits from the possibilities for following identifiable persons over long time (lifelong) and the possibilities for linking to other registers and databases. Important limitations of register research are the heterogeneity and questionable validity of the clinical data collected.
CONCLUSION: Future register research can go in the direction of big is beautiful collecting data from all possible sources creating giga-registers. In that case, low data quality will still be an unsolved problem. Or it can take the direction of smaller local clinical databases which has many advantages, for example, integrating clinical knowledge and experience into register research. However, in that case, registers will not be able to deal with rare conditions and diseases.