A patient log is one of the most critical documents in clinical research. It is the real-time register of every participant you have enrolled, tracking their study journey from screening to final follow-up. For medical thesis work, maintaining a clean, accurate patient log can mean the difference between a well-defended study and a data integrity crisis at the viva.
This guide explains what a patient log must contain, how to structure it, and how to keep it updated without letting it become a burden.
What Is a Patient Log?
A patient log (also called a subject enrollment log or participant tracking sheet) is a running record that captures who has been enrolled in your study, when, and what has happened to them at each study visit. It is separate from your main data sheet — the log is about tracking; the data sheet is about variables.
What Your Patient Log Must Include
🆔 Identification Fields
Study ID, screening number, date of enrollment, and consent form number. Never record patient names in the main log.
📅 Visit Tracking
Date of each study visit, whether the visit occurred on schedule, and reason for any missed or delayed visit.
📊 Study Status
Current status for each patient: Enrolled, Active, Completed, Withdrawn, Lost to Follow-up, or Deceased.
📝 Withdrawal Notes
If a patient exits the study early, document the date and reason — adverse event, consent withdrawal, or protocol deviation.
Setting Up Your Patient Log: A Timeline Approach
Screening Phase
Assign a sequential screening number to every patient who is assessed for eligibility, even those who are not enrolled. Record why ineligible patients were excluded.
Enrollment
Once consent is obtained, assign a Study ID. Record the consent date and the name of the person who obtained consent.
Active Follow-up
Update the log after each study visit. Mark completed visits with a date and incomplete visits with a reason code.
Study Exit
Mark each patient as Completed, Withdrawn, or Lost to Follow-up with the relevant date. This determines your final evaluable sample.
Paper vs Digital Patient Logs
Paper logs have the advantage of being universally accepted and requiring no technical setup. However, they are prone to being lost, damaged, or illegible. If you use a paper log, photocopy or photograph it weekly as a backup.
Digital logs in Excel or dedicated platforms offer search and filter functions that make it easy to see, at a glance, which patients are due for a follow-up visit or which are missing data. A digital log also makes it simple to calculate your enrollment rate over time.
Common Patient Log Errors and How to Prevent Them
- Backdating entries — Always record events on the day they occur. Backdating is a serious data integrity violation.
- Using correction fluid (Tipp-Ex) — For paper logs, always cross out errors with a single line, initial, and date. The original entry must remain readable.
- Mixing up Study IDs — Use a sequential, never-reused ID system. Once a patient exits the study, their ID is retired.
- Not updating withdrawal reasons — Incomplete withdrawal records affect your CONSORT flow diagram and may be flagged by examiners.
CONSORT Diagram and Your Patient Log
At the time of writing your thesis, your patient log is the source document for your CONSORT (or STROBE, for observational studies) flow diagram. The numbers in your flow diagram — screened, enrolled, completed, withdrawn — must exactly match your patient log. Discrepancies here raise immediate questions about study conduct.
Automate Your Patient Log with ThesisLog
ThesisLog's built-in enrollment tracker automatically updates patient status at each visit and flags overdue follow-ups — so your log is always current.
See ThesisLog Features →Key Takeaways
- Start your patient log before you enroll the first patient.
- Separate your enrollment log from your analysis dataset.
- Update the log on the same day as each patient event.
- Keep a backup of your log at least weekly.
- Reconcile your log with your data sheet monthly to catch discrepancies early.