UMIN-ICDS Clinical Trial
| Unique ID issued by UMIN | UMIN000062324 |
|---|---|
| Receipt number | R000071268 |
| Scientific Title | A Randomized Study Comparing Opt-In and Opt-Out Consent Models for Resident Physician Consultations and Case Report Publication in General Internal Medicine Outpatient Clinics |
| Date of disclosure of the study information | 2026/07/23 |
| Last modified on | 2026/07/23 23:57:14 |
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Basic information
Public title
A Randomized Study Comparing Opt-In and Opt-Out Consent Models for Resident Physician Consultations and Case Report Publication in General Internal Medicine Outpatient Clinics
Acronym
OPT-CONSENT
Scientific Title
A Randomized Study Comparing Opt-In and Opt-Out Consent Models for Resident Physician Consultations and Case Report Publication in General Internal Medicine Outpatient Clinics
Scientific Title:Acronym
OPT-CONSENT Study
Region
| Japan |
Condition
Condition
Not applicable (study of consent procedures in general internal medicine outpatients)
Classification by specialty
| Not applicable |
Classification by malignancy
Others
Genomic information
NO
Objectives
Narrative objectives1
To investigate whether the consent model (opt-in vs. opt-out) differentially affects patient consent rates for resident physician consultations and case report publication in a general internal medicine outpatient setting.
Basic objectives2
Others
Basic objectives -Others
Comparison of consent procedures (opt-in versus opt-out)
Trial characteristics_1
Exploratory
Trial characteristics_2
Pragmatic
Developmental phase
Not applicable
Assessment
Primary outcomes
Consent rates for resident physician consultation and case report publication at first visit, compared between the opt-in and opt-out groups
Key secondary outcomes
Age, sex, identity of the consenting person (self vs. proxy), presence of hospital admission indication, presence of cognitive impairment, presence of psychiatric history, and existing care at another department within the same institution at first visit, compared between the opt-in and opt-out groups.
Base
Study type
Interventional
Study design
Basic design
Parallel
Randomization
Randomized
Randomization unit
Individual
Blinding
Open -no one is blinded
Control
Active
Stratification
Dynamic allocation
Institution consideration
Blocking
Concealment
Intervention
No. of arms
2
Purpose of intervention
Educational,Counseling,Training
Type of intervention
| Other |
Interventions/Control_1
An opt-in consent form was distributed by administrative staff prior to the clinical encounter at first visit. The form addressed two items: (1) consent to be initially examined by a resident physician under the supervision of an attending physician, and (2) consent for their clinical case to be used in a published case report. Patients were required to actively indicate consent by checking a box for each item.
Interventions/Control_2
An opt-out consent form was distributed by administrative staff prior to the clinical encounter at first visit. The form addressed two items: (1) consent to be initially examined by a resident physician under the supervision of an attending physician, and (2) consent for their clinical case to be used in a published case report. Consent was presumed unless patients actively declined by checking a box for each item.
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
| 18 | years-old | <= |
Age-upper limit
| Not applicable |
Gender
Male and Female
Key inclusion criteria
New outpatients aged 18 years or older attending the general internal medicine outpatient clinic of Chiba Central Medical Center during the 15-month resident physician training period between April 2021 and January 2023
Key exclusion criteria
Patients were excluded if their consent form contained insufficient information to determine their response, if they declined participation in the study, or if written consent could not be obtained due to severe communication difficulties without a proxy available.
Target sample size
178
Research contact person
Name of lead principal investigator
| 1st name | Shingo |
| Middle name | |
| Last name | Suzuki |
Organization
Chiba Central Medical Center
Division name
Department of Internal Medicine
Zip code
264-0017
Address
1835-1 Kasori-cho, Wakaba-ku, Chiba-shi, Chiba, Japan
TEL
043-232-3691
shngszkthk@yahoo.co.jp
Public contact
Name of contact person
| 1st name | Kenta |
| Middle name | |
| Last name | Kanda |
Organization
Chiba Central Medical Center
Division name
Department of Internal Medicine
Zip code
264-0017
Address
1835-1 Kasori-cho, Wakaba-ku, Chiba-shi, Chiba, Japan
TEL
043-232-3691
Homepage URL
kenta43knd@gmail.com
Sponsor or person
Institute
Chiba Central Medical Center
Institute
Department
Personal name
Funding Source
Organization
No external funding received
Organization
Division
Category of Funding Organization
Other
Nationality of Funding Organization
Other related organizations
Co-sponsor
Name of secondary funder(s)
IRB Contact (For public release)
Organization
Chiba Central Medical Center IRB
Address
1835-1 Kasori-cho, Wakaba-ku, Chiba-shi, Chiba, Japan
Tel
043-232-3691
resident@ccmc.seikei-kai.or.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 | 07 | Month | 23 | Day |
Related information
URL releasing protocol
Currently under preparation for journal submission.
Publication of results
Unpublished
Result
URL related to results and publications
Currently under preparation for journal submission.
Number of participants that the trial has enrolled
260
Results
A total of 252 patients were analyzed (opt-in: n=142; opt-out: n=110). Consent rates for resident physician consultation did not differ significantly between groups (opt-in 81.7% vs. opt-out 84.5%; p=0.550; RR=1.03 [95% CI 0.93-1.16]). Consent rates for case report publication were significantly higher in the opt-out group (opt-in 54.9% vs. opt-out 84.5%; p<0.001; RR=1.54 [95% CI 1.30-1.82]).
Results date posted
| 2026 | Year | 07 | Month | 22 | Day |
Results Delayed
Results Delay Reason
Not applicable
Date of the first journal publication of results
Baseline Characteristics
Opt-in group (n=142): mean age 65.0 years (SD 19.4), male 83 (58.5%), self-consent 125 (88.0%), hospital admission indicated 8 (5.7%), cognitive impairment 9 (6.4%), psychiatric history 7 (4.9%), care at another department 98 (69.0%). Opt-out group (n=110): mean age 65.7 years (SD 20.4), male 51 (46.4%), self-consent 92 (83.6%), hospital admission indicated 6 (5.5%), cognitive impairment 10 (9.1%), psychiatric history 9 (8.2%), care at another department 68 (61.8%). No significant differences between groups (all p>0.200).
Participant flow
Of 260 patients who received consent forms, 8 were excluded (1 completely blank form, 7 not uploaded to the electronic medical record), leaving 252 patients for analysis (opt-in: n=142; opt-out: n=110). Group allocation of the 8 excluded patients could not be confirmed as original paper forms were unavailable.
Adverse events
No adverse events occurred in this study.
Outcome measures
[Primary] Consent rates for resident physician consultation and case report publication immediately after completion of the consent form at first visit (opt-in vs. opt-out group)
[Secondary] Age, sex, identity of consenting person (self vs. proxy), presence of hospital admission indication, cognitive impairment, psychiatric history, and existing care at another department within the same institution at first visit
Plan to share IPD
No
IPD sharing Plan description
Not applicable
Progress
Recruitment status
Completed
Date of protocol fixation
| 2021 | Year | 02 | Month | 24 | Day |
Date of IRB
| 2021 | Year | 02 | Month | 24 | Day |
Anticipated trial start date
| 2021 | Year | 04 | Month | 01 | Day |
Last follow-up date
| 2023 | Year | 01 | Month | 31 | Day |
Date of closure to data entry
Date trial data considered complete
Date analysis concluded
Other
Other related information
This trial was retrospectively registered. At the time of study initiation, the intervention (change in consent document format) was not considered to meet the ICMJE definition of a health-related intervention requiring prospective trial registration. Registration was performed retrospectively upon preparation of the manuscript for journal submission.
Management information
Registered date
| 2026 | Year | 07 | Month | 23 | Day |
Last modified on
| 2026 | Year | 07 | Month | 23 | Day |
Link to view the page
Value
https://center6.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000071268
