UMIN-CTR Clinical Trial
| Unique ID issued by UMIN | UMIN000061108 |
|---|---|
| Receipt number | R000069928 |
| Scientific Title | Concentration of Claimed Costs and Facility-Level Variation after Minor Injuries Following Motor Vehicle Accidents in Japan |
| Date of disclosure of the study information | 2026/04/01 |
| Last modified on | 2026/03/31 00:48:50 |
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Basic information
Public title
A study examining medical costs after minor traffic accident injuries and differences across medical providers
Acronym
A study of medical costs for minor traffic injuries
Scientific Title
Concentration of Claimed Costs and Facility-Level Variation after Minor Injuries Following Motor Vehicle Accidents in Japan
Scientific Title:Acronym
MICRO-COST Japan Study: Minor Injury Cost Concentration Study in Japan
Region
| Japan |
Condition
Condition
cervical sprain, lumbar sprain
Classification by specialty
| Orthopedics |
Classification by malignancy
Others
Genomic information
NO
Objectives
Narrative objectives1
Musculoskeletal pain is common in Japan and is associated with increased healthcare costs. After motor vehicle accidents, minor injuries such as cervical and lumbar sprains often lead to repeated outpatient visits and high claimed costs, particularly under compensation systems financed by third-party payers. Variation in healthcare utilization and claimed costs across regions and providers is not fully explained by clinical need. Cost concentration, in which a small subset of patients or facilities accounts for a large share of total costs, is also recognized.
In compensation systems, healthcare utilization may be influenced by administrative processes and financial incentives as well as clinical need. However, quantitative evidence on facility-level variation and cost concentration for minor injuries remains limited. Compensation has been associated with prolonged symptoms, extended care, and higher costs, while limiting compensation may reduce claims. Psychosocial factors are also related to persistent symptoms and care seeking.
In Japan, claimed costs are associated with occupation, region, and care across multiple institutions. Our previous study found no association between accident severity and treatment duration or visit frequency. Care is mainly reimbursed on a fee-for-service basis under the compulsory automobile liability insurance system, and per-visit compensation and wage-loss benefits may influence care-seeking behavior.
Basic objectives2
Others
Basic objectives -Others
Cross-sectional study
Trial characteristics_1
Trial characteristics_2
Developmental phase
Assessment
Primary outcomes
Total claimed costs from initial consultation to recovery
Key secondary outcomes
Base
Study type
Observational
Study design
Basic design
Randomization
Randomization unit
Blinding
Control
Stratification
Dynamic allocation
Institution consideration
Blocking
Concealment
Intervention
No. of arms
Purpose of intervention
Type of intervention
Interventions/Control_1
Interventions/Control_2
Interventions/Control_3
Interventions/Control_4
Interventions/Control_5
Interventions/Control_6
Interventions/Control_7
Interventions/Control_8
Interventions/Control_9
Interventions/Control_10
Eligibility
Age-lower limit
| Not applicable |
Age-upper limit
| Not applicable |
Gender
Male and Female
Key inclusion criteria
The data provided by the General Insurance Rating Organization of Japan was used, and the selection criteria were as follows: (1) injuries resulting from a motor vehicle accident (rear-end collision, contact, or impact), (2) primary diagnosis of lumbar sprain, (3) medical treatment covered by compulsory automobile liability insurance, (5) compensation using compulsory automobile liability insurance completed between June 2014 and December 2019, and (6) damages due to injury of 400,000 yen or less with no permanent disability (a minor category in Japan's no-fault government compensation), or damages due to injury of less than 1,200,000 yen with permanent disability (a minor permanent disability in Japan's no-fault government compensation).
Key exclusion criteria
Exclusion criteria included patients who suffered fractures, dislocations, or spinal cord injuries during litigation related to traffic accidents, and those with missing data.
Target sample size
284139
Research contact person
Name of lead principal investigator
| 1st name | Kenji |
| Middle name | |
| Last name | Miki |
Organization
Osaka Yukioka College of Health Science
Division name
Faculty of Health Science
Zip code
543-0027
Address
1-1-41 Sojiji, Ibaraki-shi, Osaka, Japan
TEL
81-6-6771-1227
kenji-miki@umin.ac.jp
Public contact
Name of contact person
| 1st name | Keisuke |
| Middle name | |
| Last name | Shimizu |
Organization
Chiba University
Division name
Future Medicine Education and Research Organization
Zip code
260-8670
Address
1-8-1 Inohana, Chuo Ward, Chiba City, Chiba Prefecture, Japan
TEL
0432262286
Homepage URL
kshimizu@chiba-u.jp
Sponsor or person
Institute
Osaka Yukioka College of Health Science
Institute
Department
Personal name
Funding Source
Organization
Japan Pain Fundation
Organization
Division
Category of Funding Organization
Non profit foundation
Nationality of Funding Organization
Other related organizations
Co-sponsor
Name of secondary funder(s)
IRB Contact (For public release)
Organization
Chiba University
Address
1-8-1 Inohana, Chuo Ward, Chiba City, Chiba Prefecture, Japan
Tel
043-222-7171
crc-godo@ML.chiba-u.jp
Secondary IDs
Secondary IDs
NO
Study ID_1
Org. issuing International ID_1
Study ID_2
Org. issuing International ID_2
IND to MHLW
Institutions
Institutions
Other administrative information
Date of disclosure of the study information
| 2026 | Year | 04 | Month | 01 | Day |
Related information
URL releasing protocol
Publication of results
Unpublished
Result
URL related to results and publications
Number of participants that the trial has enrolled
284139
Results
Results date posted
Results Delayed
Results Delay Reason
Date of the first journal publication of results
Baseline Characteristics
Participant flow
Adverse events
Outcome measures
Plan to share IPD
IPD sharing Plan description
Progress
Recruitment status
No longer recruiting
Date of protocol fixation
| 2026 | Year | 02 | Month | 01 | Day |
Date of IRB
| 2020 | Year | 05 | Month | 28 | Day |
Anticipated trial start date
| 2026 | Year | 02 | Month | 01 | Day |
Last follow-up date
| 2026 | Year | 12 | Month | 31 | Day |
Date of closure to data entry
Date trial data considered complete
Date analysis concluded
Other
Other related information
This study is a nationwide analysis of claims data for cervical and lumbar sprains treated under the compulsory automobile liability insurance system in Japan, using data provided by the General Insurance Rating Organization of Japan.
The aim of this study is to examine the concentration and variation of medical costs across medical institutions and related care providers, and to inform future policy on insurance-covered healthcare and social security systems.
Management information
Registered date
| 2026 | Year | 03 | Month | 31 | Day |
Last modified on
| 2026 | Year | 03 | Month | 31 | Day |
Link to view the page
Value
https://center6.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000069928
