Geographical Analysis of Aneurysmal Subarachnoid Hemorrhage in Japan Utilizing Publically-Accessible DPC Database

Abstract

Since the launch of the novel medical reimbursement system Diagnosis Procedure Combination (DPC) in 2003 in Japan, inpatient data has been accumulated over time as part of a Japanese governmental nationwide database. This is partially accessible by the public, and this study examined the adequacy of this database as epidemiological research material by extracting the data relating to aneurysmal subarachnoid hemorrhage (aSAH) with special attention given to the limitations that this involves. Datasets after 2010 are considered suitable for analysis because of the numbers of participating hospitals and the analysis term. Extracting the data by prefecture, those with a continuously high aSAH incidence were Aomori, Iwate, Akita, Yamagata, Kochi and Kumamoto Prefectures, and those with low aSAH incidence were Kanagawa, Shiga, Kyoto, Shimane and Ehime Prefectures. Although these obtained results are informative, a publically-accessible DPC database has several limitations. Some limitations have been resolved: the analyzed term each year is now 12-months and the number of participating hospitals seems to have stabilized around 1700. However, other limitations such as masking the numbers in each hospital reporting less than 10 patients still exist, so careful and critical interpretation is necessary in utilizing a publically-accessible DPC database. Considering the potential of this database as material for epidemiological research, future analysis of the entire DPC database by qualified researchers is desirable.

Aneurysmal subarachnoid hemorrhage: Geography has a role

“…There have been two recent studies in this direction. One study by Fukuhara[ 25 ] was done in Japan. The use of the diagnosis procedure combination database for epidemiological studies was analyzed.…”

Prefectural difference in spontaneous intracerebral hemorrhage incidence in Japan analyzed with publically accessible diagnosis procedure combination data: possibilities and limitations

“…However, when utilizing publically accessible DPC data, as in this article, other specific limitations occur. The limitations inherent to the publically accessible DPC data are significant and this may account for the paucity of articles utilizing these data [ 5 , 22 ]. Analyses with the whole body of the DPC database are able to utilize more detailed information for each patient.…”

“…As for the prefectural sICH incidence, hospitals were grouped according to the prefecture in which they were located, then the sICH patient number for each prefecture was summed up. This number divided by the prefectural population is defined as the prefectural sICH incidence; however, this number is further contaminated by the “masked rate” [ 5 ]. This occurs because patient numbers treated in hospitals with fewer than 10 patients in a year were not reported, thus the patient numbers obtained as the prefectural sICH incidence resulted in smaller numbers than those captured by the DPC database.…”

“…The recent expansion of electronic medical records has enabled large amounts of information to be prepared for medical analysis [ 4 ]. In Japan, a novel medical reimbursement system for hospitalization, named the Diagnosis Procedure Combination (DPC) system, was launched in 2003, based on electronic medical records from physicians, submitted by hospitals participating in this system to the Japan Ministry of Health, Labor, and Welfare (JMHLW) [ 5 ]. These data are analyzed by the government and the summarized data are officially reported once a year.…”

“…However, in utilizing publically accessible DPC data, careful attention should be paid to the limitations of the data [ 5 ]. As illustrated in Figure 1 , the actual sICH incidence in Japan is unknown because of uncaptured sICH patients at hospitals that do not submit DPC data (non-DPC hospitals).…”