Monitoring Visits and Source Data Verification
Monitoring is the sponsor's quality-control function, executed by the CRA under a written plan. ICH E6 5.18 lists what a monitor verifies: investigator qualifications and resources, protocol compliance, informed consent for every subject, accuracy and completeness of source and CRF data, safety reporting, IP accountability, and facilities.
Know the vocabulary
- SDV (source data verification): comparing source documents against the CRF/EDC entry, usually on a sampling basis defined by the monitoring plan.
- SDR (source data review): reading source documents for quality, completeness, and consistency to detect issues SDV sampling may miss.
- Risk-based monitoring: E6(R2) permits centralised and remote monitoring, with on-site visits targeted at higher-risk sites and data.
- ALCOA-C: attributable, legible, contemporaneous, original, accurate, complete (plus enduring and available).
Visit mechanics
Pre-visit letter and data review → on-site verification and interviews → close-out meeting with the investigator → written monitoring report (E6 5.18.6) → follow-up letter listing findings and actions. Reports are written after every visit and within sponsor-defined timelines; findings are graded, and serious or persistent non-compliance escalates.
Traps
- Believing the monitor may write in, correct, or "tidy" source documents - the monitor reviews and documents; the site corrects with attributable, dated entries.
- Forgetting that consent review covers every enrolled subject, not a sample.
- Missing a consent signed by staff not on the delegation log, or by a coordinator who signed before the subject.
- Treating low SDV percentages as universal - the monitoring plan governs.
Worked example: source shows visit date 12 March; EDC says 21 March. Document the discrepancy, ask the site to correct the erroneous entry with an audit-trailed change, and confirm which date is true - never "fix" the database to match a guess.