Aggravation and Causation Are Different Prongs

Paragraph (a) is the one everybody quotes. A disability proximately due to or the result of a service-connected disease or injury shall be service connected. Caused by.

Paragraph (b) is the other one. Any increase in severity of a nonservice-connected disease or injury that is proximately due to or the result of a service-connected disease or injury, and not due to the natural progress of the nonservice-connected disease, will be service connected.

Read that again with the emphasis in the right place. Increase in severity. Not the condition. The increase.

The two prongs cover different situations and they are not interchangeable. Under (a) a condition would not be there at all without the service-connected one. Under (b) the condition was already there, and something service-connected pushed it further than it would otherwise have gone. A person can be in the second situation and not the first, and most guides give them nothing to read about it.

Because it requires a before and the first prong does not.

The regulation is explicit. VA will not concede aggravation unless the baseline level of severity is established by medical evidence created before the onset of aggravation, or by the earliest medical evidence created at any time between the onset of aggravation and the evidence establishing the current level.

That is a records problem in the shape of a legal standard. To show that something got worse, there has to be a record of how bad it was earlier. Not a memory of it. A document. For anybody who went years without seeing a doctor about a condition that was tolerable at the time, which is a great many people, the before does not exist and cannot be created afterwards.

This is the practical reason aggravation gets dropped from guides. It is harder to write about than causation because the answer is often about what is missing from a file rather than what is in it.

By subtraction, and this catches people out.

The regulation says the rating activity will determine the baseline and current levels of severity under the rating schedule. It then says to work out the extent of aggravation by deducting two things from the current level: the baseline level of severity, and any increase due to the natural progress of the disease.

So there are three quantities and only one of them is the answer. Where the condition is now. Where it was at baseline. And how much of the change the disease was going to do on its own anyway.

The first, minus the other two. That remainder is what the second prong addresses.

That last subtraction is worth sitting with, because natural progress is doing a lot of work in that sentence. Arthritis progresses. Kidney function declines. Hearing thresholds shift with age. The regulation asks how much of the worsening was extra, and that is a harder question than whether worsening happened.

Nearly all the literature on condition pairs measures incidence. It takes people who do not have condition B, follows them, and counts how many develop it. Every risk ratio and hazard ratio in a standard secondary conditions list is that kind of number. It is exactly the right evidence for prong (a) and it is close to silent on prong (b).

Aggravation asks something else: among people who already have condition B, does having condition A make B get worse faster? That is a study of progression, and progression studies are rarer, harder to fund and harder to run. Nobody designed it that way to be unhelpful. It is simply how research questions get chosen.

The consequence is that the abundance of evidence for causation and the scarcity of evidence for aggravation is a fact about study design, not a fact about bodies. Aggravation being poorly evidenced in the literature does not mean aggravation is rare.

The ones that measured change rather than presence. There are three recognizable shapes, and knowing them lets you tell quickly whether a paper is relevant to this prong at all.

Studies of what happens after treatment. A pooled analysis of sleep apnea and atrial fibrillation found the strongest odds not for new atrial fibrillation but for it coming back after an ablation procedure, at 2.93 against 1.71 for new onset with no obvious cause (PMID 35905270). Recurrence after treatment is a progression measure. Most summaries of that paper quote only the first number.

Studies of what happens when the first condition improves. Veterans in VA specialty care whose PTSD scores dropped substantially went on to develop diabetes at 2.6 percent against 5.9 percent for those whose scores did not (PMID 31433443). Watching B change as A changes is a different kind of evidence from counting who has both.

Studies that grade severity over time rather than counting cases. The knee arthritis literature does this. A review of 13 reviews reports that surgery on a torn cruciate ligament does not reduce arthritis in the longer term compared with managing it without surgery (PMID 33852440).

The study of people who had one knee replaced does it too, and its answer is pointed. What best predicted the other knee following was that knee's own arthritis grade before the first operation. Age, sex, weight and which side was operated on predicted nothing (PMID 12913941).

That last finding is a caution aimed squarely at this prong. The most repeated aggravation story in this whole subject is that a bad joint on one side wears out the other side. The best study of it found the other side's own starting condition was what mattered.

The change, in terms somebody can measure, as close to when it happens as possible.

Not a diagnosis and not a theory about which condition is doing it. What a clinician can act on is a described change: further than last year, more often than it used to be, a distance that used to be walkable and is not now. Those get examined, and an examination produces a record with a date on it.

A date is the part that matters here more than anywhere else in this subject, because the standard in the regulation is about a before and an after. A record created today is a baseline for something that gets worse in three years, whether or not that is why it was created.

A free VSO can file with what is already in a record and can say what the record does and does not contain. They are accredited and they do not charge. That is the right first stop, and it costs nothing to use.

No, and the word doing double duty is a genuine source of confusion.

Aggravation appears in two different places in the regulations. One is about a condition that existed before service and got worse during it. The other, the one on this page, is about a condition made worse by an already service-connected condition. The glossary entry on aggravation covers both homes of the term and is the place to read the definitions.

They share a word and almost nothing else. Reading advice written about one while being in the other is an easy mistake and a costly one.