ALCOA and ALCOA+ Data Integrity in Clinical Trials: What the Acronym Actually Requires

At a glance

• ALCOA is five attributes every data record must hold: attributable, legible, contemporaneous, original, accurate. It is the working definition of data integrity, not a poster.
• ALCOA+ adds four more in common use: complete, consistent, enduring, available. The substance of these is grounded in the same data-integrity expectations, even where the ”+” labels are industry shorthand.
• It applies to source records and to their metadata. A value with no context (no unit, no who, no when) is not original or attributable, however neat it looks.
• For electronic records, the contemporaneous and attributable attributes are enforced by a secure, time-stamped audit trail that cannot obscure the prior entry. Disabling that audit trail is a data-integrity failure, not a configuration choice.
• Where teams get it wrong: backfilling records “to be tidy,” treating audit-trail review as optional, and confusing a printout with the original dynamic record.

What ALCOA actually is

ALCOA is the acronym FDA uses to define the attributes of trustworthy data. In FDA’s own words, complete, consistent, and accurate data should be attributable, legible, contemporaneously recorded, original or a true copy, and accurate, which is ALCOA (FDA Data Integrity and Compliance With Drug CGMP guidance, ALCOA definition). Unpacked, the five are:

Attribute	The requirement
Attributable	You can tell who recorded the data and when.
Legible	It can be read and understood, and stays readable for the record’s life.
Contemporaneous	It was recorded at the time the activity happened, not reconstructed later.
Original	It is the first capture, or a verified true copy of it, not a transcription.
Accurate	It is correct, with no errors introduced between the event and the record.

ICH E6(R3) states the same five for clinical source records and adds the sixth that the ”+” later formalises. Under §2.12.2, source records should be attributable, legible, contemporaneous, original, accurate and complete, and changes to source records should be traceable, should not obscure the original entry, and should be explained if necessary via an audit trail (ICH E6(R3) §2.12.2). The principle behind all of it sits one section up: the investigator should ensure the integrity of data under their responsibility, irrespective of the media used (ICH E6(R3) §2.12.1). Paper or electronic, the standard is the same.

ALCOA+: the four common extensions

ALCOA+ adds complete, consistent, enduring, and available. These are widely used across GxP, and the underlying obligations are grounded rather than decorative. “Complete” is already explicit in ICH E6(R3) §2.12.2 and in FDA’s “complete, consistent, and accurate data” framing. “Enduring” and “available” follow from FDA’s expectation that data should be maintained throughout the record’s retention period with all associated metadata required to reconstruct the activity (FDA Data Integrity guidance, metadata). Treat the ”+” as a memory aid that closes the loop from creation to retrieval, not as a separate, lighter standard.

It is about the data and its metadata

A number on its own is not data; it is a digit. FDA is explicit that metadata is the contextual information required to understand data, and that data should be maintained throughout the record’s retention period with all associated metadata required to reconstruct the activity (FDA Data Integrity guidance, metadata). The classic example: “23” means nothing until metadata supplies the unit, the timestamp, the person, and the instrument. So an integrity programme that protects values but loses the audit trail, the user ID, or the time stamp has not protected the data. ICH E6(R3) builds metadata into the investigator’s review duties and into sponsor quality control.

This is why “tidying up” records is the cardinal sin. Re-entering yesterday’s readings today, in one clean hand, destroys contemporaneousness and originality at a stroke. The messy, time-stamped original is the trustworthy record; the neat reconstruction is the finding.

How electronic systems enforce it: the audit trail

For electronic records the attributable and contemporaneous attributes are not a matter of good intentions; they are enforced by the system’s audit trail. 21 CFR Part 11 §11.10(e) requires closed systems to use secure, computer-generated, time-stamped audit trails to independently record the date and time of operator entries and actions that create, modify, or delete electronic records, and record changes shall not obscure previously recorded information (21 CFR Part 11 §11.10(e)). That last clause is ALCOA in a sentence: you may correct data, but you may never erase the history of the correction.

It follows that the audit trail has to stay on. ICH E6(R3) requires ensuring that audit trails, reports and logs are not disabled (ICH E6(R3), computerised-systems oversight). An audit trail that can be switched off is not a control; it is a liability waiting for an inspection. And an audit trail nobody reads is only half a control: FDA frames audit-trail review as analogous to reviewing cross-outs on paper data, which means it is part of the review of the data itself, not a separate IT chore.

The control questions to hold yourself to

FDA offers a practical self-test that converts ALCOA from theory into checks. Ask whether controls ensure data is complete, whether activities are documented at the time of performance and attributable to a specific individual, whether only authorised individuals can make changes, whether there is a record of those changes, whether records are reviewed for accuracy and completeness, and whether data are maintained securely from creation through disposition after the retention period (FDA Data Integrity guidance, control questions). If any answer is “not reliably,” that is where your integrity risk lives.

Static versus dynamic: why a printout is not the original

The “printout is not the original” point has a precise basis. FDA distinguishes record formats: static indicates a fixed-data record such as a paper record or an electronic image, while dynamic means the record format allows interaction between the user and the record content (FDA Data Integrity guidance, static and dynamic records). A chromatogram, a database query, an audit trail: these are dynamic. You can re-process them, re-sort them, drill into them. Flatten one to a PDF and you have captured a snapshot while discarding the interactivity, the metadata, and often the audit trail that made it trustworthy. That is why retaining the static printout in place of the dynamic original is a data-integrity failure, not a filing preference. The original is the dynamic record, and it is the dynamic record you must keep and be able to reproduce.

This is also where the connection between ALCOA and computerized-system controls becomes concrete. ALCOA is the property; Part 11 is part of how you engineer it. 21 CFR Part 11 §11.10(a) requires validation of systems to ensure accuracy, reliability, consistent intended performance, and the ability to discern invalid or altered records, which is the system-level guarantee behind “accurate” and “original.” And §11.10(d) requires limiting system access to authorized individuals, which is the control behind “attributable,” because a record can only be tied to who made it if the system knew who that was and kept others out. Attributability is not a field you fill in; it is a consequence of access control done properly.

So the practical reading of ALCOA for an electronic system is layered. The system has to be validated so its records are reliable and tamper-evidence is real (Part 11 §11.10(a)); access has to be controlled so every action is attributable to a known, authorized person (Part 11 §11.10(d)); the audit trail has to be on, secure, and time-stamped so changes never obscure the original (Part 11 §11.10(e)); and the dynamic record, with its metadata, has to be the thing retained, not a static shadow of it. Miss any layer and one of the ALCOA attributes quietly stops being true even though the data still looks clean on screen.

Where teams get it wrong

• Backfilling for neatness. Recording later, in one clean pass, breaks contemporaneousness and originality. The original messy entry is the trustworthy one.
• Treating audit-trail review as optional. FDA treats it as part of reviewing the data. Capturing an audit trail and never reading it leaves manipulation invisible.
• Disabling or permitting disable of audit trails. ICH E6(R3) requires they not be disabled. A system that allows it is a finding regardless of whether anyone used the switch.
• Confusing a printout with the original. A static printout of a dynamic electronic record is not the original; the dynamic record, with its metadata and audit trail, is what must be retained.
• Shared logins. When several people sign in as one account, every action becomes attributable to nobody in particular, which quietly defeats the first letter of ALCOA. Attributability is built on the access control of Part 11 §11.10(d), not on a signature line.
• Protecting values but losing metadata. Data without the who, when, and unit cannot be reconstructed, so it fails ALCOA even if the numbers are right.

Data integrity is not a documentation exercise bolted on at the end. It is the property that lets a reviewer trust every number in the trial, traced to who recorded it, when, and from what original. ALCOA is just the checklist for whether you have it.

Sources

• ICH E6(R3) Good Clinical Practice, version R3
• 21 CFR Part 11, Electronic Records; Electronic Signatures (current as of 4/14/2026)
• FDA, Data Integrity and Compliance With Drug CGMP: Questions and Answers (2018)