Secondary service connection: when one condition leads to another

Conditions rarely stay in their own lane. A knee injury changes how you walk. A chronic pain condition affects sleep and mood. Medication for one condition can cause problems somewhere else. VA recognizes this through secondary service connection: a condition can be service connected because of a condition that is already service connected, even if it didn't start in service.

Two ways a secondary claim works

• Causation (38 CFR § 3.310(a)): the service-connected condition caused the new one.
• Aggravation (38 CFR § 3.310(b)): the service-connected condition made the other one worse than it would otherwise be, beyond its natural progress.

These are separate questions, and a good medical opinion addresses both. An opinion that only says “not caused by” without addressing aggravation leaves part of the question unanswered, and VA's own exams sometimes stop there.

Common patterns

Every case depends on the individual record, but some patterns come up often:

• Altered gait and joint loading. A service-connected knee, ankle or foot condition can change how weight moves through the hips and lower back over time.
• Pain, sleep and mental health. Chronic pain and mental health conditions can affect sleep, and each can worsen the others.
• Medication effects. Long-term medication for a service-connected condition can have effects on other organ systems.

Our secondary & associated conditions page covers more examples, with the medical literature behind them.

What the evidence needs to show

1. A current diagnosis of the secondary condition.
2. An established service-connected condition it relates to.
3. A medical opinion explaining how the first condition caused or worsened the second, at least as likely as not, with reasoning and supporting literature.

Whether you're filing on your own or working with a VSO, an accredited claims agent or an attorney, the medical opinion is often the piece that decides a secondary claim. That's the part we focus on.

References

1. 38 CFR § 3.310, Disabilities that are proximately due to, or aggravated by, service-connected disease or injury. LII
2. Allen v. Brown, 7 Vet. App. 439 (1995) (en banc): secondary service connection by aggravation.
3. El-Amin v. Shinseki, 26 Vet. App. 136 (2013): an opinion must address aggravation, not only causation.

This article is general information, not medical or legal advice. Every claim depends on its own record.