Table 1. Characteristics of the Included Studies According to Data Type.

From: Literature Review of Studies Using the National Database of the Health Insurance Claims of Japan (NDB): Limitations and Strategies in Using the NDB for Research

Number of studies All General data Sampling data Accumulated data Open data
Total 267 % 151 % 27 % 15 % 74 %
Theme Medical treatment status 125 46.8 51 33.8 20 74.1 7 46.7 47 63.5
Clinical epidemiology, course of diseases 67 25.1 40 26.5 8 29.6 8 53.3 11 14.9
Socioeconomic comparison (e.g., prefecture) 46 17.2 12 7.9 1 3.7 3 20.0 30 40.5
Intervention effect 45 16.9 42 27.8 1 3.7 0 0.0 2 2.7
Research methodology 26 9.7 15 9.9 1 3.7 6 40.0 4 5.4
Health policy evaluation and utilization 26 9.7 14 9.3 2 7.4 0 0.0 10 13.5
Health economics 19 7.1 13 8.6 0 0.0 0 0.0 6 8.1
Quality of care 16 6.0 8 5.3 7 25.9 0 0.0 1 1.4
Patient health service utilization 13 4.9 10 6.6 0 0.0 0 0.0 3 4.1
Others 10 3.7 6 4.0 3 11.1 0 0.0 1 1.4
Prediction model 5 1.9 1 0.7 0 0.0 1 6.7 3 4.1
Age Children 17 6.4 12 7.9 3 11.1 0 0.0 2 2.7
Older persons 21 7.9 17 11.3 2 7.4 1 6.7 1 1.4
Adults 66 24.7 44 29.1 5 18.5 2 13.3 15 20.3
No age limit/Others 163 61.0 78 51.7 17 63.0 12 80.0 56 75.7
Disease 1) Certain infectious and parasitic diseases 30 11.2 18 11.9 8 29.6 2 13.3 2 2.7
2) Neoplasms 14 5.2 5 3.3 5 18.5 1 6.7 3 4.1
3) Diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism 0 0.0 0 0.0 0 0.0 0 0.0 0 0.0
4) Endocrine, nutritional, and metabolic diseases 25 9.4 20 13.2 1 3.7 0 0.0 4 5.4
5) Mental, Behavioral, and Neurodevelopmental disorders 23 8.6 13 8.6 4 14.8 1 6.7 5 6.8
6) Diseases of the nervous system 18 6.7 11 7.3 1 3.7 0 0.0 6 8.1
7) Diseases of the eye and adnexa 5 1.9 3 2.0 1 3.7 0 0.0 1 1.4
8) Diseases of the ear and mastoid process 0 0.0 0 0.0 0 0.0 0 0.0 0 0.0
9) Diseases of the circulatory system 38 14.2 27 17.9 5 18.5 0 0.0 6 8.1
10) Diseases of the respiratory system 12 4.5 7 4.6 3 11.1 2 13.3 0 0.0
11) Diseases of the digestive system 21 7.9 11 7.3 0 0.0 0 0.0 10 13.5
12) Diseases of the skin and subcutaneous tissue 4 1.5 3 2.0 0 0.0 0 0.0 1 1.4
13) Diseases of the musculoskeletal system and connective tissue 30 11.2 21 13.9 0 0.0 1 6.7 8 10.8
14) Diseases of the genitourinary system 9 3.4 4 2.6 2 7.4 0 0.0 3 4.1
15) Pregnancy, childbirth, and the puerperium 5 1.9 3 2.0 1 3.7 1 6.7 0 0.0
16) Certain conditions originating in the perinatal period 1 0.4 0 0.0 0 0.0 0 0.0 1 1.4
17) Congenital malformations, deformations, and chromosomal abnormalities 4 1.5 3 2.0 0 0.0 0 0.0 1 1.4
18) Injury, poisoning, and certain other consequences of external causes 29 10.9 20 13.2 2 7.4 2 13.3 5 6.8
19) Others (multidisease, not focused on specific diseases) 53 19.9 21 13.9 3 11.1 6 40.0 23 31.1
*Theme and disease: up to two categories are selected
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