Patient-Reported Outcomes in Medical Device Trials: PRO Instruments, Validation, and FDA/EU Expectations

Why PROs Matter for Medical Devices

Patient-reported outcomes (PROs) capture how patients feel, function, and survive — directly from the patient, without interpretation by clinicians or anyone else. For medical devices, PROs have moved from optional supplementary data to a central component of regulatory submissions. The FDA's CDRH has been actively promoting the integration of patient perspectives throughout the total product lifecycle, and EU MDR clinical evaluation requirements increasingly expect evidence of patient-relevant outcomes.

FDA's draft guidance on "Principles for Selecting, Developing, Modifying, and Adapting Patient-Reported Outcome Instruments for Use in Medical Device Evaluation" (Docket FDA-2020-D-1564) establishes the framework for using PROs in device evaluations. The guidance emphasizes that PRO instruments must be fit-for-purpose — meaning they must generate relevant, reliable, and sufficiently robust data for the specific context of use in the regulatory decision.

Regulatory Framework

FDA Framework

CDRH PRO Guidance (draft):

• Published to further integrate patient input throughout the medical device lifecycle
• Encourages collection, analysis, and integration of patient perspectives in device development and evaluation
• Establishes the fit-for-purpose standard for PRO instruments
• Applicable to premarket submissions (510(k), De Novo, PMA), IDE studies, and post-market surveillance

Patient-Focused Drug Development (PFDD) Guidance Series:

• Guidance 3 (finalized October 2025): "Selecting, Developing, or Modifying Fit-for-Purpose Clinical Outcome Assessments"
• Guidance 4 (draft April 2023): "Incorporating Clinical Outcome Assessments Into Endpoints for Regulatory Decision-Making"
• While primarily drug-focused, CDRH has adopted many of these principles for devices

FDA PRO Compendium:

• CDRH maintains a publicly available PRO Compendium listing PRO instruments that have been used in medical device premarket clinical investigations
• Serves as a reference but does not constitute endorsement of any instrument

EU MDR Framework

• Article 61 and Annex XIV: Clinical evaluation must include assessment of clinical performance, which can include patient-relevant outcomes
• Annex I GSPR 1: Devices must achieve the performance intended by their manufacturer, including aspects relevant to patient quality of life
• MDCG 2020-6: Sufficient clinical evidence guidance references the importance of patient-relevant endpoints
• PMCF activities: Post-market clinical follow-up under Annex XIV Part B may include patient-reported outcome measures to track long-term safety and performance

Types of Clinical Outcome Assessments

FDA recognizes four categories of clinical outcome assessments (COAs), each with distinct characteristics:

The Growing Role of PROs in Device Submissions

PROs are no longer optional supplementary data in device trials. Over 75% of FDA investigational device exemptions (IDEs) have included at least one PRO endpoint, reflecting CDRH's emphasis on patient-relevant evidence. This trend has accelerated with the 2025 finalization of PFDD Guidance 3, which establishes the "fit-for-purpose" standard as the baseline expectation for all COAs used in regulatory decision-making.

When PROs Add the Most Value

PROs are particularly important for medical devices where:

• The device directly affects symptoms perceived by the patient (e.g., pain management devices)
• Functional improvement is a primary outcome (e.g., orthopedic implants, surgical robots)
• Quality of life is a key differentiator (e.g., minimally invasive vs. open surgery)
• The treatment effect is primarily subjective (e.g., hearing aids, neurostimulators)
• Patient adherence or satisfaction affects outcomes (e.g., insulin pumps, continuous glucose monitors)
• Labeling claims reference patient experience (e.g., "improved comfort," "faster return to daily activities")

Selecting a PRO Instrument

The Fit-for-Purpose Standard

FDA's guidance establishes three factors for selecting a PRO instrument:

1. Concept of Interest

• What aspect of the patient's health is being measured?
• Is it a symptom, functional status, or health-related quality of life?
• Is the concept meaningful to patients in the target population?

2. Context of Use

• How will the PRO data be used in the regulatory decision?
• Is it a primary endpoint, secondary endpoint, or exploratory?
• What is the specific trial population, disease severity, and treatment setting?

3. Measurement Properties

• Does the instrument have adequate evidence of reliability, validity, and responsiveness?
• Has it been validated in a population similar to your trial population?
• Is it sensitive enough to detect clinically meaningful changes?

Decision Framework for PRO Selection

Is there an existing validated PRO instrument for your concept of interest
in your target population?
    │
    YES ─────────────────────────────── NO
    │                                    │
    Use the existing instrument          Can an existing instrument be
    Document validation evidence         modified for your context?
    Confirm fit for purpose                   │
                                    YES ────────── NO
                                    │              │
                                    Modify and     Develop a new
                                    revalidate     instrument with
                                    in your        patient input
                                    population     and psychometric
                                                   testing

Common PRO Instruments Used in Device Trials

PRO Instrument Validation Requirements

Core Measurement Properties

FDA expects evidence of the following measurement properties for any PRO instrument used in a regulatory submission:

Reliability:

• Test-retest reliability: Does the instrument produce consistent results when the patient's condition has not changed? Measured using intraclass correlation coefficient (ICC ≥ 0.70 typically required)
• Internal consistency: Do items within a domain measure the same construct? Measured using Cronbach's alpha (≥ 0.70)
• Inter-rater reliability: Not typically applicable for PROs (self-report), but relevant if interview-administered

Validity:

• Content validity: Does the instrument capture all aspects of the concept important to patients? Established through qualitative research with the target patient population
• Construct validity: Does the instrument correlate with other measures of the same or related constructs?
  • Convergent validity: Correlates with measures of similar constructs
  • Discriminant validity: Does not correlate with measures of unrelated constructs
  • Known-groups validity: Distinguishes between groups expected to differ
• Criterion validity: Correlates with a gold standard measure (when one exists)

Responsiveness (sensitivity to change):

• Can the instrument detect clinically meaningful changes over time?
• Establish the minimal important difference (MID) — the smallest change that patients perceive as meaningful

Validation Evidence Hierarchy

Best Practices for Validation Documentation

FDA's draft guidance recommends that sponsors:

1. Engage patients early — Conduct focus groups or interviews with the target population to identify meaningful health aspects and concepts of interest
2. Use cognitive interviewing — Test whether patients understand the instrument items as intended
3. Document the conceptual framework — Map each item to the concept it measures
4. Conduct psychometric analysis — Quantify reliability, validity, and responsiveness with appropriate statistical methods
5. Define the scoring algorithm — Specify how individual items are combined into domain and summary scores
6. Establish the MID — Determine the threshold for clinically meaningful change
7. Assess respondent burden — Ensure the instrument is not excessively long or complex
8. Consider accessibility — Address literacy level, language, cultural adaptation, and mode of administration
9. Leverage real-world data for validation — Where additional validation evidence is needed, FDA suggests that real-world data analyses may be helpful in deriving evidence to support PRO instrument use
10. Consider pre-competitive collaboration — FDA encourages sponsors and stakeholders to collaborate on PRO instrument development and adaptation

PROs as Endpoints in Device Trials

Endpoint Hierarchy

Sample Size Considerations

When a PRO serves as a primary endpoint:

• Power the study to detect a difference at or above the established MID
• Account for missing data (PROs often have higher dropout rates than objective measures)
• Consider multiplicity adjustments if multiple PRO endpoints are tested
• Pre-specify the primary PRO endpoint and its analysis method in the statistical analysis plan

Handling Missing PRO Data

Missing PRO data is common in device trials because patients may miss follow-up visits or fail to complete questionnaires. Plan for this:

• Prevention: Minimize burden, use electronic PRO (ePRO) capture with reminders, train site staff
• Documentation: Record reasons for missing data
• Analysis: Pre-specify methods for handling missing data (mixed models for repeated measures, multiple imputation, tipping-point analysis)
• Sensitivity analyses: Test whether conclusions are robust to different assumptions about missing data

Electronic PRO (ePRO) Implementation

Electronic capture of PRO data via tablets, smartphones, or web-based applications is increasingly the standard in device trials. FDA accepts ePRO data provided that:

• The electronic instrument is equivalent to the paper version (validation evidence required)
• The system captures the date and time of completion
• Audit trails are maintained per 21 CFR Part 11 requirements
• Data are stored securely with appropriate access controls
• The system is validated according to GAMP 5 / computer system validation standards

Advantages of ePRO:

• Real-time data capture with timestamping
• Reduced missing data through automated reminders
• Elimination of transcription errors
• Compliance tracking
• Ability to capture data remotely (important for decentralized clinical trials)

PROs and Regulatory Submission Strategy

FDA Pre-Submissions

FDA strongly encourages sponsors to discuss PRO plans through the Q-Submission program before conducting pivotal trials. CDRH specifically recommends pre-submission meetings to discuss:

• Selection of PRO instruments
• Validation evidence and any gaps
• Endpoint definitions and analysis plans
• Integration with the overall clinical study design
• Electronic PRO implementation

EU MDR Notified Body Expectations

Notified Bodies reviewing CERs increasingly expect to see:

• Patient-relevant endpoints in the clinical evaluation plan
• PRO data integrated into the benefit-risk assessment
• Justification if PROs are not collected (especially for devices with direct patient interfaces)
• PMCF activities that include patient-reported outcome monitoring

Labeling Claims Based on PROs

PRO data can support device labeling claims in both the US and EU:

FDA: PRO-based claims must be supported by validated instruments and statistically significant results. Claims language must accurately reflect the PRO endpoint and population studied.

EU MDR: IFU and SSCP may reference patient-relevant outcomes. Claims must be consistent with the clinical evidence in the CER.

Practical Checklist

• Identify patient-relevant endpoints early in the clinical development plan
• Select fit-for-purpose PRO instruments with validation evidence in a similar population
• If developing or modifying an instrument, engage patients in the development process
• Document all validation evidence and measurement properties
• Pre-specify PRO endpoints in the statistical analysis plan
• Power the study to detect clinically meaningful differences (at or above the MID)
• Use ePRO with Part 11 compliant audit trails
• Plan for missing data with pre-specified handling methods
• Submit PRO plans to FDA via Q-Submission for early feedback
• Integrate PRO findings into the CER benefit-risk assessment
• Include PRO collection in PMCF activities for post-market monitoring
• Ensure evaluator qualifications include expertise in PRO methodology