Rheumatoid arthritis as seen from official data registers. Experience in Finland.

Computerized public data registers are an important data base for bodies monitoring public health. They can also be used for epidemiological research. The main problems in the use of the registers are administrative and qualitative. The use, and especially the linking of different registers together, is strictly regulated by law. The trend seems to be towards more strict regulations. Another problem is the quality of the data. The registers were designed for administrative purposes and therefore, the classification of data is not always suitable for research. In addition, errors are possible at several stages of the production and filing of the data. International comparisons are difficult because of differences in legislation and administrative rules. However, despite these problems, public data registers are an important resource for research, and their importance will grow with time and improvements in the quality of the registers.