Background: Observational studies using large claims databases for diabetes patients have been increasingly conducted. While validation of outcomes is important in such studies, validation studies from Japan are still scarce and small in scale with questions remaining on the representativeness of their findings. We examined the positive predictive value (PPV) of outcomes that often develop in type 2 diabetes patients: cardiovascular outcomes including congestive heart failure (CHF), myocardial infarction (MI), stroke-related diseases, and renal outcomes including end stage renal disease (ESRD), and death using a large Japanese database containing administrative claims and electronic medical record (EMR) data. Patients and Methods: We used patient-level administrative claims data from 2003 and EMR data from 1985 to the most recent data up to December 2018 provided by Real World Data Co., Ltd. The database consisted of data from over 200 hospitals including ≥12 million uniquely identifiable patients. Among patients who had ≥1 type 2 diabetes diagnosis in the EMR, those who had administrative claims for each outcome were identified, and then the PPV was calculated for each outcome using the EMR as the gold standard. Results: The numbers of patients identified for each outcome were 1,700 for MI, 2,027 for hemorrhagic stroke, 3,722 for ESRD, 4,723 for ischemic stroke, 5,404 for CHF, 6,678 for any type of stroke, and 10,815 for death. PPVs ranged from 67.4% for ESRD, 78.7% for MI, 80.3% for death, 85.7% for ischemic stroke, 88.9% for any type of stroke, 89.9% for hemorrhagic stroke, and 95.7% for CHF. A post hoc analysis showed PPV for ESRD as 83.8%. Conclusion: This large-scale validation study on diagnosis in administrative claims showed reasonable PPVs for the outcomes. We believe that the definitions of outcomes can be considered to be appropriate for future studies using Japanese administrative claims data.

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Aims: Various drugs have recently been launched for the treatment of multiple myeloma (MM). This increase in the number of treatment options has potentially changed treatment patterns and medical costs for patients with MM. Japanese public health insurance claims were analyzed to examine the change in the treatment patterns of MM drugs and medical costs per patient. Materials and methods: A claims database provided by Medical Data Vision was used, which includes data from 20 million patients from >300 acute care hospitals across Japan. The type of MM drugs prescribed and medical costs for patients with MM between April 2008 and December 2016 were examined using monthly cross-sectional analyses. Patients with an International Classification of Diseases, 10th Revision (ICD-10) diagnosis code of C90.0 were classified as having MM. MM drugs were defined by generic names. Results: In total, 19,137 patients with MM (average age at first diagnosis: 69.6 years; percentage of women: 47.9%) were identified from the database. The percentage of patients prescribed each MM drug changed substantially as novel drugs were launched. Total medical costs increased until 2010, then stabilized. MM drug costs increased from approximately 2010, but costs for other care decreased, particularly for hospitalization (including surgery). Limitations: The database contained data from large, acute care hospitals, which may have caused bias in terms of patients' clinical history and disease severity. Conclusions: Total medical costs for MM have remained stable since 2010. MM drug costs increased, but costs for other care decreased after the launch of lenalidomide in 2010 and other drugs in 2015 and later. More detailed research is required to confirm whether the launch of novel drugs caused the changes in medical costs.

Hypertension requires strict treatment because it causes diseases that can lead to death. Although various classes of antihypertensive drugs are available, the actual status of antihypertensive drug selection and the transition in prescription patterns over time have not been fully examined. Therefore, we conducted a claims-based study using two claims databases (2008-16) to determine this status in Japan. We examined the prescription rate for each class of antihypertensive drugs in hypertensive patients and compared the patients' ages and the sizes of the medical institutions treating these patients. Among the 1 560 865 and 302 433 hypertensive patients in each database, calcium channel blockers (CCBs) (>60%) and angiotensin II receptor blockers (ARBs) (>55%) were the most frequently prescribed classes. The prescription rate of CCBs increased and ARBs decreased with the patients' ages. Although the Japanese guidelines for management of hypertension in 2014 changed the recommendation and indicated that β-blockers should not be used as first-line drugs, their prescription status did not change during this study period up to 2016. Use of CCBs and ARBs as first-line drugs differed by the types of patient comorbidities. Although ARBs or angiotensin-converting enzyme inhibitors were recommended for patients with some comorbidities, CCBs were used relatively frequently. In conclusion, the patients' ages and comorbidities and the sizes of the medical institutions affect the selection of antihypertensive drugs. Selection and use of drugs may not always follow the guidelines.

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