LAUSR

DOI: 10.1111/iju.13840 The Ministry of Health, Labor and Welfare released the second NDB Open Data Japan in October 2017. NDB Open Data Japan is a fundamental table summarizing Japanese national universal healthcare insurance claims. The database comprises almost all (≥95%) claims data regarding medical and dental treatments, and specific health checkups, and it provides us a complete picture of the real-world clinical practice in Japan. The data are openly available for free on the website, http://www.mhlw.go.jp/stf/seisakunitsuite/bunya/0000177182.html. The period in the first and second NDB Open Data Japan were the fiscal year 2014 and 2015 (12 months from April to the next March). Because of its ultimately high representativeness, it enables us to know how widely our urological clinical practice varies by geographic regions. This visualization would wield a notable impact on both physicians and patients to understand the current standard of care, to examine future health policies locally and to promote urological healthcare uniformity globally. Because the spreadsheets of the NDB Open Data were written in insurance technical codes, we believe a physician-friendly reformat would be widely welcomed to enhance its recognition and effective utilization. For example, Table 1 is a list of the prevalence of minimally invasive surgery in nephrectomy and nephroureterectomy for malignancy in each prefecture in the fiscal year 2015, with the prevalence proportion appearing in descending order. Minimally invasive surgery is defined as laparoscopic and minimal incision endoscopic surgery. Robot-assisted surgery was not included due to non-coverage in national universal healthcare insurance at that time. Although minimally invasive surgery accounted for 64.9% throughout Japan, the prefectural proportion widely varied from 93.9% in Miyazaki to 25.0% in Yamagata. Because the share of minimally invasive surgery between 2007 and 2010 was reported to be 42.1% based on the Diagnosis Procedure Combination database, it had increased by half from 2010 to 2015. Regarding geographic regional variation, the rate of minimally invasive surgery was >70% in the western areas, and <60% in the eastern area, except Hokkaido. The previous Diagnosis Procedure Combination database study also pointed out a distribution discrepancy between eastern and western areas. A definitive reason for the variation could not be drawn from the database analysis; however, it would be reasonable to mention that highlyskilled laparoscopic surgeons would likely be produced in high-prevalence areas where there was suitable laparoscopic training, and the increasing number of skilled surgeons contributes further to spreading minimally invasive surgery in the region. A detailed table on prefectural distribution of urological surgical procedures in a physicianfriendly format is provided as Table S1. Some comments should be added for interpretation of the table. First, any individual cell counts <10 were not available to maintain confidentiality. When such a cell was single, all the other cell counts become unavailable to block back calculation. This cell size suppression policy was set to avoid the potential identification risk of individuals. Second, the second NDB Open Data Japan in the fiscal year 2015 separated inpatient and outpatient procedures, whereas the first NDB Open Data Japan in the fiscal year 2014 showed combined data only. Owing to the rules, prefectural counts in extracorporeal shockwave lithotripsy at outpatient settings were unavailable in the fiscal year 2015. Therefore, prefectural inpatient–outpatient combined counts in the fiscal year 2015 were estimated by being prorated from the counterpart of the fiscal year 2014, and then the outpatient counts in the fiscal year 2015 were calculated by combined counts minus inpatient counts. Third, because some patients travel across the prefectures, the hospital-based counts in this manuscript could lead to overor underestimation of residence-based counts. The NDB Open Data included other types of data, such as distribution of age and sex regarding medical procedures, counts of most frequently prescribed drugs for each therapeutic category, and results of specific health checkups. A database with near-complete capture of healthcare services like the NDB has a great potential to solve a wide range of clinical and healthcare questions. In the USA, 100% of the Medicare dataset was used for several analyses including epidemiology study; treatment utilization variation; the relationship among cost, safety, effectiveness and quality; and the Urological Notes