Croatia limited-capacity participant and legal representative consent requirements

When this variation is required

Conditional. Use a legal-representative pathway when an adult cannot understand, retain, weigh, or communicate the information needed for the specific participation decision and Croatian law recognises a representative authorised to decide for that person.

The trial must also satisfy Article 31 of the Clinical Trials Regulation. It must be necessary in relation to people lacking capacity, relate directly to the participant's condition or be of a permitted population-benefit type, and meet the applicable benefit, risk, and burden limits.

Do not assume that a spouse, adult child, caregiver, study partner, or family member is the legally appointed representative. Central Ethics Committee guidance describes the guardian or legal representative as a person appointed by a court. Verify the appointment and scope before enrollment.

Documents to prepare

Mandatory. Prepare a full Croatian informed consent for the legally appointed representative. Explain the trial, why the represented person is eligible, the representative's role, the participant's wishes, procedures, risks, benefit prospects, alternatives, data, samples, costs, insurance, withdrawal, and later consent if capacity returns.

Mandatory. Prepare Croatian information for the participant in a form they can understand. Adapt words, length, layout, images, or supported-communication methods to the person's actual ability. Provide a signature or assent field when the participant can make or record a meaningful choice.

Conditional. Prepare separate documents for optional sample use, genetics, pregnancy follow-up, a required caregiver or study partner, and other third-party data collection. The representative's main-trial decision must not silently authorise unrelated optional research.

Submit blank, versioned, and dated documents under Subject information and informed consent form. They are not signed at CTIS submission.

Consent and signature logic

The legal representative and the physician or dentist conducting the consent interview sign and date the paper informed consent when consent is obtained. Croatian law limits the interviewer role to the principal investigator or a delegated investigator who is a physician or dentist. The representative receives a signed copy.

Involve the participant as far as possible. Explain the trial at the level they can understand, ask about wishes and concerns, and record assent where appropriate. A representative's signature does not erase the participant's autonomy.

Article 31 requires explicit wishes by a participant capable of forming an opinion to refuse participation or withdraw to be respected. Do not restrain, pressure, or override the participant because the legal representative agreed.

Current Croatian guidance requires routine consent to be obtained in person on paper. Electronic consent is reserved for exceptional circumstances and must be followed by in-person paper consent when possible.

Croatian restriction for mental-disorder trials

Central Ethics Committee guidance states that people under guardianship who cannot independently decide may not participate in clinical trials of psychopharmaceuticals. It also states that trials conducted in people with mental disorders should plan to include adults with legal capacity.

Treat this as a material Croatian feasibility restriction. If a proposed protocol includes adults lacking capacity in a psychiatric or psychopharmaceutical trial, seek written advice from the Ministry of Health and Central Ethics Committee before relying on a general Article 31 analysis. Do not prepare the dossier on the assumption that representative consent alone will make the population acceptable.

Older Croatian clinical-trial rules also refer to a positive opinion from the committee responsible for protecting people with mental disorders before such a trial starts. Confirm the current procedural route with the authorities for the specific application.

Re-consent when capacity changes

Mandatory. If the participant gains or regains capacity, provide the approved adult participant information and obtain their own informed consent for continued participation at the first appropriate opportunity. Record the capacity assessment and the date of re-consent.

If capacity fluctuates, the protocol and consent procedure should explain when capacity is reassessed, who performs the assessment, how urgent safety decisions are handled, and how the participant's present wishes are respected.

If the participant refuses after regaining capacity, stop future trial participation according to the approved withdrawal process. Explain what happens to previously collected data and samples without overstating the sponsor's right to retain or use them.

Data, samples, and third parties

Explain the representative's authority and the participant's own data-protection rights. Provide controller, privacy, transfer, retention, and AZOP contacts. Do not ask the representative to give blanket permission for direct access to health information from unrelated healthcare professionals. Croatian national specifics say trial health information is obtained from the participant or legal representative.

For biological samples, explain storage, use, transfers, withdrawal, and final handling. Optional future research normally needs a distinct choice or document. If capacity later returns, revisit optional permissions as well as continued trial participation.

If a caregiver or study partner must provide data, that person completes a separate consent process. A caregiver is not automatically the legal representative, and a legal representative is not automatically the day-to-day caregiver.

Croatia-specific final checks

• The representative's legal authority and scope are verified.
• The participant receives Croatian information suited to their ability.
• The main representative consent and any optional consents are distinct.
• The participant's objection, distress, resistance, and previously expressed wishes are addressed.
• The representative and physician or dentist interviewer sign and date in person on paper.
• Re-consent is planned if capacity returns.
• Psychiatric and psychopharmaceutical restrictions are assessed with the Croatian authorities before submission.
• Data, sample, pregnancy, caregiver, and contact-person documents cover every applicable third party.

If immediate treatment cannot be delayed and no prior consent can be obtained, do not improvise this pathway. Use the separate Croatia emergency enrollment guide. Return to the Croatia CTIS hub for the full guide collection.