Direct comparison
SDV vs SDR: Verification vs Review
SDV checks CRF data line-by-line against source; SDR reviews source documents for quality and compliance. How risk-based monitoring splits the two.
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How do Source Data Verification (SDV), Source Data Review (SDR) compare side by side?
The table below compares Source Data Verification (SDV), Source Data Review (SDR) across 10 procurement-relevant dimensions, from what it is through where it shows up in documentation.
Side-by-side comparison
| Dimension | Source Data Verification (SDV) | Source Data Review (SDR) |
|---|---|---|
| What it is | Line-by-line comparison of each case report form (CRF) entry against the source document it was transcribed from | Structured review of the source document itself — completeness, internal consistency, documentation quality, protocol adherence |
| Primary question it answers | Does this CRF value match the source? | Is the source record itself complete, consistent, and compliant with the protocol? |
| Traditional / typical coverage | Historically 100% of data points, all subjects and visits, on many legacy monitoring plans | A risk-based sample of visits, subjects, or sites, sized to risk rather than transcription volume |
| Regulatory anchor | ICH E6(R2) source data/source document definitions (§1.51-1.52); a long-standing monitoring practice, not itself a numeric mandate | ICH E6(R2) §5.0 quality management (critical data/processes, quality tolerance limits) and §5.18.3 centralized/risk-based monitoring; FDA's 2013 risk-based monitoring guidance |
| What sets how much is done | Data criticality (safety data, primary/key secondary endpoints) and known or likely site-specific risk | The same two factors — site risk profile and data criticality — applied to review depth and sampling rather than a per-field percentage |
| Who typically performs it | A CRA, on-site or remote, in a transcription-check style pass during a monitoring visit | A CRA or centralized reviewer, often paired with centralized/statistical monitoring of the accumulating dataset |
| Efficiency rationale | Resource-intensive at 100%; a 2024 scoping review (PMC11639101) found no settled evidence base showing 100% SDV eliminates data errors | Lower cost per record reviewed; frees monitoring resources toward higher-risk sites and data, which FDA's guidance cites as the point of risk-based monitoring |
| Risk if scaled back without a plan | Reducing SDV without knowing its detection sensitivity for a given error type runs counter to GCP quality-management expectations | A review-only approach with no defined escalation path can miss issues that only a line-level check would have caught on the most critical fields |
| Position in a monitoring plan | Targeted to the critical/high-risk data points named in the trial's risk assessment — rarely eliminated outright | Covers lower-risk, high-volume data and overall site conduct, complementing rather than replacing targeted SDV |
| Where it shows up in documentation | Monitoring visit reports, tracked against the SDV plan for each data category | Monitoring visit reports plus centralized-monitoring and quality-tolerance-limit reports |
Common questions
Common questions about Source Data Verification (SDV) vs Source Data Review (SDR)
Does risk-based monitoring eliminate SDV entirely?
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Rarely. Neither ICH E6(R2) nor FDA's risk-based monitoring guidance mandates a specific SDV percentage, and most trials retain targeted SDV on the data ICH E6(R2) treats as critical to safety or study results. Reduced or eliminated SDV applies to lower-criticality, lower-risk data — not across the board.
Is SDR a replacement for SDV?
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No — they check different things. SDV confirms a specific transcribed value matches its source document; SDR examines whether the source record and site processes are complete and protocol-compliant. A risk-based monitoring plan typically uses both, weighted by data criticality and site risk rather than picking one exclusively.
What determines a site's SDV/SDR mix?
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Two factors: data criticality (how directly a given field affects safety or a primary/key secondary endpoint) and the site's risk profile (enrollment volume, protocol deviation history, staff experience, prior audit or inspection findings). Higher criticality and higher site risk both push toward more SDV; lower-risk, high-volume data is a better fit for SDR or centralized review.
Does ICH E6(R3) change this further?
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E6(R3) places even more explicit emphasis on risk-based quality management than R2 did, reinforcing rather than reversing the shift toward SDR and reduced SDV. Sponsors are still expected to document the rationale for whatever monitoring approach and verification depth they choose.
Who decides the SDV/SDR split for a trial?
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The sponsor, through the risk assessment that feeds the monitoring plan required under ICH E6(R2) §5.0. That assessment names the critical data and processes, sets quality tolerance limits, and documents why a given site or data category gets targeted SDV, SDR, or a defined mix of both.
Going deeper
