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Nationwide Population Science: Lessons From the Taiwan National Health Insurance Research Database.

Large population-based studies can inform us on the prevalence, incidence, natural history, treatment, correlates, and associations of disease, as well as the pattern of health care utilization. A special type of large population study encompasses the population of an entire nation. Advantages include enormous sample size and lack of selection and participation bias. These advantages are enhanced further when the databases are rich in clinical, personal, and risk factor information and when different pieces of information are linked to permit joint analysis. Once the process for data accessing is established, vast amounts of information can be obtained at minimal cost, especially when additional collection and update of information is carried out routinely for purposes inherent in medical care and/or insurance coverage and reimbursement. The Taiwan National Health Insurance (NHI) Research Database is one of the largest nationwide population databases in the world, covering approximately 23 million residents in Taiwan.1 The NHI program was established in 1995 to deliver universal coverage provided by a government-run, single-payer compulsory insurance plan to centralize the disbursement of health care funding. The program covered 99.0% of the island population by 2004 and 99.5% of the population by 2010. Universal coverage reduces barriers to health care access for all citizens, regardless of socioeconomic background and/or residential location. In 1997, the National Health Research Institute was authorized to build the NHI Research Database to facilitate research on health care utilization, health economics, and biomedical and behavioral research, as well as to provide information guiding national health policy. Currently, the NHI Research Database includes more than 26 data files containing information on personal characteristics (sex, date of birth, place of residence, details of insurance, employment); family relationships; details of clinical information, including date, expenditures, and diagnosis related to both inpatient and outpatient procedures; prescription details; examinations; and operations. Data are updated biannually. Since 2003, the use of electronic medical records has been mandated and standardized across 321 hospitals, providing the foundation for digital health and data exchange. By law, all Taiwan residents have a unique personal identification number that is used also for tax returns, bank accounts, and all transactions. Thus, NHI Research Database data are linkable to multiple national databases maintained by other departments, including registries of births, deaths, households, immunizations, cancer, reportable infectious diseases, and environmental exposures. This identification is also linked to the national immunization information system and mass population-based screening for cancers of the oral cavity, colon, cervix, and breast, as well as myopia and urine screenings and regular examinations in school children, newborn screening, the rare disease and suicide registries, the Taiwan Pathogenic Microorganism Genome Database, and the blood donor registry. A health cloud is currently being built that will eventually further facilitate data linkage among various registries, databases, and departments. In addition, Academia Sinica is establishing a biobank of more than 200 000 residents; the data in the biobank will be linked with NHI Research Database data. With such extensive linkage, privacy is protected through laws that dictate encryption of the unique personal identification number (23 digits) and strict procedures for data access and human subject review. To date, no breach or leak is known to have occurred. Since 1995, several large data centers have been established in academic universities in Taiwan to mine the NHI Research Database. More than 2016 articles had been published by mid2014 (http://nhipapers.idv.tw/healthdata/advance_ch.php), including studies of drug adverse effects and risk of disease (n = 163), drug safety and efficacy (n = 131), drug prescription and utilization patterns (n = 169), clinical presentation (n = 117), prognosis and health outcomes research (n = 682), costeffectiveness and health economics (n = 90), health services research (n = 81), health care utilization (n = 220), methodology (n = 46), ecologic correlation (n = 46), and risk factor analysis (n = 56), as well as descriptive studies (n = 215) and studies of other topics.2-4 Productivity is rapidly accelerating, with more than 430 studies published in 2013. The large and longitudinal nature of the data (nearly 20 years of follow-up data of the entire population) permits a wide range of study design, including cross-sectional, case-control, and retrospective and prospective cohort analyses, as well as family studies (family members can be linked through parents’ identification numbers on birth certificates). The large sample size provides opportunities for the study of rare conditions. For example, in this issue of JAMA Internal Medicine, Kuo et al5 identified 18 283 patients with systemic lupus erythematosus (SLE) and their family members, including parents, siblings, and twins, to estimate SLE heritability, risk for specific family members, and relationships with other autoimmune diseases. Typically, SLE studies include up to a few hundred cases, and even large consortia, such as those conducting genome-wide association studies, usually include no more than several hundred to several thousand cases. Some other countries (Japan, Korea, and Scandinavian countries [eg, Sweden and Denmark]) also have national databases with associated record linkage capacity. However, relative to Taiwan, the population size for Scandinavian Related article page 1518 Aggregation of Systemic Lupus and Other Autoimmune Diseases Original Investigation Research