Secondary analysis of existing data sets can be a cost-effective approach to conduct health research. In Taiwan, the availability of the claimed data from the single-payer, mandatory national health insurance program (the National Health Insurance Research Database, NHIRD) [1] for investigators has created unprecedented research opportunities, which has resulted in a wave of publications based on the NHIRD in the past decade or so. A PubMed search using the keyword“National Health Insurance Research Database”, with restriction to articles published in the last 10years, yielded over 1400 publications.