How Do Workers' Comp Reviewers Separate a Work Injury From a Pre-Existing Condition?

The claim file says the low back injury happened on 14 March, lifting a pallet. The claimant's primary care records show a visit for low back pain in November 2019, six years earlier, with two sessions of physical therapy and nothing after that.

So which is it?

That question is not yours to answer, and it is not the reviewer's either. But whether the evaluating physician can answer it well depends almost entirely on whether the pre-existing condition evidence in the workers' comp medical records reached them clearly, with dates attached, or arrived as 900 unsorted pages with a 2019 note buried at page 412.

Most guidance on this topic is written for injured workers asking whether a prior condition kills their claim. This is written for the people on the other side of the file: the adjusters, defense teams, QME coordinators and reviewers who have to make the record legible before anyone can evaluate it.

What the Record Really Contains

Medical records almost never label anything pre-existing. That word belongs to the claim, not the chart.

What the record contains is a complaint documented on a date by a named provider, sometimes with imaging, sometimes with treatment, often with nothing following it. That is the job a medical record review does here: surface each of those entries and let the pattern be visible.

The Four Things Worth Isolating

• Prior complaints of the same body part, documented, dated, with the provider named
• Prior diagnostics, because imaging predating the injury shows anatomical state before the event
• Prior treatment and its end point, since two therapy sessions in 2019 is a different picture from eighteen months of pain management ending three weeks before the injury
• Documented symptom-free periods, meaning stretches with no complaints of that body part at all

That last one gets overlooked. A reviewer who flags the 2019 back visit but does not note that nothing followed it for six years has given the evaluator half a picture, and the more alarming half.

Why the Sequence Matters

Workers' comp turns on what changed and when. A record set that cannot show the before and after clearly makes every later determination harder.

Baseline First

Build the pre-injury picture before reading anything post-injury. What conditions were documented, what treatment was underway, what work restrictions existed, what the last relevant visit said.

This is where work restriction review changes case preparation. A restriction documented before the injury date and a restriction issued after it look identical in a flat chronological list, and they mean entirely different things.

Then the Post-Injury Course

Read the treatment after the date of injury against that baseline. New findings, changed findings, unchanged findings. The comparison is what carries information, not either half on its own.

A useful review makes that comparison possible on one page. It does not make the comparison for you.

Where These Files Go Wrong

Five failures show up again and again in workers' comp record sets.

Prior Records Never Requested

The claim file contains post-injury treatment and nothing else. Nobody requested the five years of primary care records that would establish the baseline. The review should say so in plain terms rather than reviewing what arrived and stopping there.

Copied-Forward History

Electronic records carry problem lists forward indefinitely. "History of lumbar strain" can appear in a 2026 note because someone typed it in 2019 and it has propagated ever since. The reviewer should trace it to the earliest note that documents it, not count each repetition as evidence, which is the same reason different source types carry different weight.

The Undated Reference

A note says the claimant "has had back trouble in the past." No date, no provider, no record behind it. That is a statement in a chart, not a documented prior condition, and a review should present it as exactly that.

Body Part Drift

Prior neck complaints get read as prior back complaints because both land under "spine." The level and the side matter. L4 to L5 in 2019 and C5 to C6 today are not the same history.

Conclusions Written Into the Summary

A summary that says "pre-existing degenerative condition, not work related" has crossed the line. So has one that says "no evidence of prior injury" when what it means is that no prior records were produced. The first is an opinion. The second is a gap described as a finding.

What a Reviewer Should Produce

A workers' comp reviewer working this question well delivers a file where the following are each findable in under a minute.

The Six Elements

1. A dated prior complaint list for the injured body part, each with provider and page citation
2. Pre-injury diagnostics listed separately, with the radiologist's read attached
3. The last documented pre-injury visit for that body part, with its findings
4. Symptom-free intervals stated as date ranges
5. Post-injury course in parallel, so before and after read side by side
6. A pending list naming providers whose records were requested but not received

Questions to Ask Before You Rely on a Review

• Which prior records are in the file, and which were requested but never arrived?
• Is each prior complaint traced to its earliest documenting note?
• Are prior complaints matched to the same body part and level as the claim?
• Are symptom-free periods stated, or only the complaints?
• Does the summary anywhere characterize a condition as related or unrelated?
• Who verified this after any AI-assisted extraction?

Where the Review Stops

This is the part that matters most in workers' comp, because the pressure to cross the line is strongest here.

Medical record review identifies, dates, organizes and flags what the documents say. It does not determine causation. It does not apportion between a pre-existing condition and a work injury. It does not decide compensability, impairment or disability.

Those are determinations for the evaluating physician, the QME or the parties, and a review that makes them quietly has damaged the input those professionals rely on. The related read here is how prior symptoms are handled in disability claim reviews, which works through the same problem in a different claim type.

The most useful thing a reviewer can write is the least conclusive: what the record documented, on what date, by whom, and what is missing.

The Bottom Line

Nobody is asking the record review to decide whether the pallet caused the injury. They are asking it to make the 2019 note, the six quiet years, and the post-injury imaging visible in the same place, at the same time, with dates attached.

Get that right and the physician can do their work. Get it wrong, or let a conclusion slip into the summary, and everything built on top inherits the error. Medical summaries in workers' comp claims live or die on that discipline, and the wider medical record review library covers the rest of the file problems this one touches.