OBJECTIVES: Medical research and data-driven healthcare depend on having access to large well-curated datasets from many sources. However, combining data on a single-patient level is slow due to data protection procedures. Combining anonymous level data lacks these challenges but requires the development of algorithms to produce meaningful results. The objective of this research was to develop algorithms for producing and combining anonymous data especially on medication use and to study their validity against current data sources in Finland. METHODS: We developed a set of algorithms to produce relevant k-anonymous statistics from various national registers in Finland and to combine them in an interactive dashboard visualization. Single-patient level data is combined within registers and only anonymous data is transferred. Anonymous data is updated on a yearly basis. Medication use data is combined at the ATC code level. The national health registers in Finland contain both medications and diagnoses. An algorithm produces anonymous data that combine these, providing information on the indication of medicines. RESULTS: Yearly medication sales, DDD estimated and reimbursed patient numbers were combined at the ATC code level. Infliximab was chosen as an example for further analysis since it has multiple indications. Based on the algorithm, the most common indications during year 2018 were 24 % for ulcerative colitis, 23 % for Crohn’s disease, 11 % for ankylosing spondylitis, 11 % for seropositive rheumatoid arthritis and 9 % for psoriasis. CONCLUSIONS: Combining data from multiple sources provides novel insight on the use of medications in Finland, especially on indications. Additionally, anonymous level data provides a possibility to do feasibility studies for medical research based on diagnoses and medications. Algorithms are needed to produce meaningful results from anonymous data and to estimate their validity. Further study is needed on the validity of the inpatient medication data in the health registers in Finland.