[What can registries contribute to health services research?]

Background: Registries are structured collections of data from a prespecified group of patients. Registry data from patients treated in routine clinical care can be used to answer numerous questions, ranging from clinical to health services research. Objectives: This article provides an overview of key applications of registry data. Materials and methods: Three key applications of registry data are illustrated based on an exploratory search of published literature. Results: Registry data create transparency regarding patients and treatments in routine care, e.g., use and effectiveness of treatment outside of clinical trials, where patients are often older and have comorbidities. Hence, registries can be key for quality assurance of patient care. In addition, they allow long-term observation of patients and identification of rare side effects. Registries are a key tool for health services research to generate hypotheses, e.g., concerning the optional treatment of specific groups of patients for whom no randomized controlled clinical trials have been conducted. Furthermore, risk profiles and prognostic scores can be developed using registry data. Finally, application of registry data has also recently become a topic of discussion for regulatory filings during approval and benefit assessments of novel treatments when evidence from clinical trials is considered insufficient. Conclusion: Numerous questions concerning optimal patient care cannot be answered with randomized controlled clinical trials alone. High quality, prospectively collected registry data can fill this gap.