A paper diary is a booklet the participant fills in and returns. An ePRO diary is the same questionnaire on a phone or tablet, with a time stamp on every entry, reminders, rules that stop skipped items, and data that arrives in the study database without anyone retyping it. The biggest difference is not convenience. It is whether you can tell when an entry was actually made.
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Evening symptom diary · demo
Day 9 of 28
How tired did you feel today?
0 is not tired at all, 5 is extremely tired
Did you take today’s study dose?
Notes
Optional
The direct answer
The comparison
A paper diary is simple to start and invisible to the study team until it is returned. Weeks can pass between an entry and anyone seeing it. If the booklet is lost, damaged or never filled in, that surfaces at the next visit. An ePRO diary is visible within minutes of submission, so missed entries and worrying scores can be acted on while the participant is still in the study. Our diary completion rates page covers how to read and improve that picture.
The core quality problem with paper is that the entry date is whatever the participant writes. People under-report missed days, fill in several at once, or complete a week’s entries in the waiting room. Time-stamped electronic entries, completion windows and reminders turn "was it completed on time" into data. See reminders by SMS and email for the mechanics.
Paper allows blanks, two circled answers and impossible values. A well-built electronic form can require an answer, allow one choice where one is meant, and apply skip logic so irrelevant questions disappear. Scores can be calculated rather than transcribed.
Paper needs to be collected, checked and keyed into the study database, then often verified. That step adds delay and error. ePRO data goes straight into the study record. If you are moving a study off paper CRFs more generally, see paper CRF to eCRF conversion.
Electronic diaries can reduce burden when participants already use a phone, because there is no booklet to carry. They add burden when the interface is poor, the link does not work or the participant has no suitable device. A browser-based questionnaire that needs no app install, as in our BYOD ePRO approach, removes one common barrier.
Side by side
| Paper diary | ePRO diary | |
|---|---|---|
| When was it completed? | Participant’s written date, hard to verify | System time stamp on each entry |
| Visibility to the team | When the booklet is returned | Within minutes of submission |
| Missing and invalid answers | Blanks, double answers and out-of-range values possible | Required fields, single-choice controls and ranges can be enforced |
| Scoring | Calculated later, by hand or in the database | Calculated automatically where configured |
| Reminders | None, or a phone call | Scheduled reminders when due, next day and before the window closes |
| Data entry | Transcribed into the database, then verified | Arrives directly in the study record |
| Audit trail | Corrections on the paper, visible but informal | Changes recorded with who, when, old and new value |
| Set-up effort | Printing and distribution | Questionnaire build and testing |
| Device needs | None | A phone or tablet, the participant’s own or provided by the site |
| Fits best | Very small or low-tech settings, backup mode | Frequent diaries, longer studies, remote or multi-site designs |
The right answer is often a hybrid: electronic by default, paper as a backup for participants who cannot use a device.
In practice
The comparison is clearest when you look at what the study team can see. With a paper diary, the team sees a returned booklet. With an electronic diary, the team sees a schedule, completion status and the participants who are at risk of missing their window.
At-risk participants
Decision
Choose ePRO. This is where the timing and burden advantages are largest.
Choose ePRO if you can. Being able to show when entries were made protects the endpoint.
Choose ePRO. A paper booklet needs shipping and return, and slows the data.
Either works. A tablet at the site visit is simple, and paper is fine if volumes are tiny.
Use paper, or provide a device. Document the decision and the mode used for each participant.
Check that the instrument is valid in each mode, and record the mode with every response.
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Switching
Moving an instrument from paper to a screen can alter how people answer. Layout, scale display, wording and recall period should stay faithful to the original, and many instruments have licence terms that cover electronic use. Read the rights holder’s terms before you build. FDA’s final PRO guidance (December 2009, non-binding) stresses instrument development and, for electronic instruments, investigator control of and access to the electronic source records. Check the current text.
Plan the failure modes too: what happens when a participant has no signal, replaces their phone, or misses a day. Write the rules for late entries and window closure into the protocol or study manual rather than discovering them live. Our guide to running patient diaries in clinical trials walks through that set-up.
Honest fit
Capture is a good fit: a link opens the questionnaire in the browser, no app to install, with reminders and a compliance view.
Capture can hold the study record for both, with paper responses entered by site staff. Record the mode used.
Possible, but the licence is your responsibility. Capture records licence details on participant questionnaires; it does not verify licences or supply instrument wording.
Do not rely on it. Capture makes no offline-completion claim, so if your population often has no signal, plan for paper or another approach.
Not what Capture is. It runs in the browser on phones and tablets.
Both collect patient-reported outcomes. A paper diary is a booklet completed by hand and returned; an ePRO diary is completed on a phone or tablet, with time-stamped entries, reminders, built-in rules and direct delivery to the study database.
They are more verifiable. A 2002 study in 80 chronic pain patients (Stone et al., BMJ) found paper diary entries were rarely made within the allowed window compared with what participants reported, while electronic compliance was high. It was one small study, so do not read it as a universal rate.
It depends. ePRO shifts cost from printing, shipping, data entry and verification to set-up and licences. For larger or longer studies it often comes out ahead, and for very small ones paper can be cheaper. Compare your own numbers.
Yes, and many studies do, with paper as a backup for participants who cannot use a device. Make sure the instrument is valid in each mode and record which mode each response used.
Not with Capture. Participants open a link on their phone in the browser. Other products may require an app.
Capture makes no offline-completion claim, so assume participants need a connection when they submit and plan an alternative, such as paper, for populations with unreliable connectivity.
Often, but check the licence for electronic use and keep layout and wording faithful to the original. Capture lets you record licence details on a participant questionnaire but does not verify licences or supply instruments.
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Keep exploring
What is ePRO?
The concept in plain English.
eCOA vs ePRO
Where ePRO sits inside eCOA.
Patient diary software for clinical trials
The diary feature set in Capture.
Diary completion rates
Measuring and improving compliance.
ePRO cost per patient
Putting numbers on the switch.
Capture ePRO
Participant questionnaires in the browser.
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