Lab reference
Anti-CCP
What the research found.
Anti-CCP caught 67 percent of rheumatoid arthritis cases and cleared 95 percent of the people who didn't have it. A positive result multiplied the odds of the disease by 12.46. A negative result multiplied them by 0.36, which barely moves them at all.
In that review, rheumatoid factor caught 69 percent of cases. That's a shade better than anti-CCP managed, and it cleared only 85 percent of the people who didn't have the disease, which is ten points worse. That second figure is the whole reason anti-CCP counts for more in the diagnostic rules.
Nishimura and colleagues, Annals of Internal Medicine, 2007
One review looked across 151 studies. The share of cases caught ranged from 12 to 93 percent, and the share of healthy people cleared ranged from 63 to 100 percent. So a single pooled figure hides a great deal of variation between one lab and the next.
In early rheumatoid arthritis the better-designed studies put the catch rate at 54 percent, while other study designs put it at 66 percent. So the test misses more early disease than the headline figure suggests. Early is when it gets ordered most and when treatment counts most.
Whiting and colleagues, Annals of Internal Medicine, 2010
What the number means.
| Result | What the evidence gives | What it means | Source |
|---|---|---|---|
| A positive result | Clears 95 percent of healthy people. Multiplies the odds by 12.46. | In someone with swollen, stiff joints this backs rheumatoid arthritis hard. | Nishimura 2007 |
| A negative result | Catches 67 percent of cases | About a third of people with the disease test negative. So this doesn't rule it out. | Nishimura 2007 |
| A negative result in early disease | Catches 54 percent in the better studies | Worse early on, which is when the test gets ordered most. | Whiting 2010 |
| The same test across labs | Catches 12 to 93 percent. Clears 63 to 100 percent. | Labs differ enough that a pooled figure hides the spread. | Whiting 2010 |
| A level to aim at | Not established | This test backs a diagnosis. It isn't followed to a goal number. | No source, because no target is set |
A reference range is not a target. Where a range on this page differs from the one your laboratory prints, the difference is explained above and sourced below. Where no trial has tested a target, this page says so rather than offering one.
What the test measures
The anti-CCP test looks for antibodies against cyclic citrullinated peptides. Citrullination is a normal chemical change that happens to proteins all over the body, and in some people the immune system starts treating those changed proteins as foreign. The antibodies it makes against them are what this test finds.
Those antibodies belong to a wider family called ACPA, which stands for anti-citrullinated protein antibodies, and you may see either name on a result. The anti-CCP form is the one most labs run. When a rheumatologist orders it, they're asking one question, which is whether your immune system has made this particular antibody against your own tissue.
How well it performs
One review of accuracy studies gives the figures that count. Anti-CCP caught 67 percent of rheumatoid arthritis cases, with a true value somewhere from 62 to 72 percent, and it cleared 95 percent of the people who didn't have the disease, with a true value from 94 to 97 percent. A positive result multiplied the odds of the disease by 12.46, and a negative result multiplied them by 0.36.
Those last two numbers describe the test's character neatly. A positive result multiplies the odds by more than twelve, which is a large move, while a negative result multiplies them by about a third, which barely moves them. So this is a test built to confirm rather than one built to rule out.
Why it beats rheumatoid factor
The comparison teaches you something, because the two tests are close on one measure and far apart on the other. In that review, rheumatoid factor caught 69 percent of cases, a shade better than anti-CCP's 67 percent. It cleared only 85 percent of healthy people, against anti-CCP's 95 percent.
That ten point difference is the whole story. Rheumatoid factor turns positive in a range of other illnesses, in some infections, and in healthy people more and more often as they age, while anti-CCP does that far less. So a positive anti-CCP points much more directly at rheumatoid arthritis, which is why it counts for more in the diagnostic rules.
Note that both tests miss about a third of people with the disease. That is the part left out when they get compared, and it is also the part that costs people a diagnosis and the years that follow it. Being better than rheumatoid factor is not the same as being good.
How much the labs vary
A larger review of 151 studies adds a caution the pooled figures hide. Its own pooled figures, from 138 studies, were a catch rate of 67 percent and a clear rate of 96 percent, which closely match the other review. Look across the individual studies, though, and the catch rate ranged from 12 to 93 percent while the clear rate ranged from 63 to 100 percent.
How the studies were built explains part of that spread. Cohort studies gave a catch rate of 60 percent, case-control studies gave 68 percent, and cross-sectional studies gave 69 percent. In early rheumatoid arthritis in particular, cohort studies gave 54 percent, with a true value somewhere from 48 to 60 percent, while the other designs gave 66 percent.
That early-disease figure deserves your attention. Early disease is when the test gets ordered most and when treatment counts most, and a test that misses nearly half of early cases is a different instrument from one that misses a third. The more careful study designs give the lower number, so a negative result in early symptoms counts for even less than the pooled figure suggests.
What a positive result means
A positive anti-CCP in someone with swollen joints backs a diagnosis of rheumatoid arthritis hard. A positive result on its own means something different, though, because in someone with no symptoms and normal joints it isn't a diagnosis and shouldn't be treated as one. These antibodies can turn up in the blood years before any joint symptoms start, and not everyone who has them goes on to get the disease.
The result also says something about how the disease may go. One review looked at four studies, and three of them found joints wearing away faster on X-ray in the anti-CCP group than in the rheumatoid factor group. That's a thin evidence base for a claim people state confidently.
A rheumatologist seeing a positive result alongside early joint symptoms will still usually treat faster, and that's a fair response to a move in the odds. It isn't a prediction about any one person. This number can't tell you how your own joints will look in ten years.
What a negative result doesn't rule out
About a third of people with rheumatoid arthritis test negative for anti-CCP, and they have the disease anyway. Doctors call that seronegative rheumatoid arthritis, and it gets diagnosed on your symptoms, on which joints are involved, on scans, and on your blood markers of inflammation rather than on antibodies. A negative result never overrules a rheumatologist examining your joints.
So suppose you've been told your antibody tests are negative and your joints are still swollen and stiff. That combination still needs a rheumatology assessment. A negative antibody result isn't a reason to send you away, because seronegative disease causes the same damage as the antibody-positive kind when it goes untreated.
A late diagnosis is a common experience for people in this group, and it is worth knowing that before it happens to you. If somebody has told you your bloods are clear and your hands still swell in the morning, that second half of the sentence is the one to repeat back to them. The swelling is the finding, and the antibody is only a clue.
Repeating the test
Anti-CCP isn't used to follow how active your disease is, because the levels don't reliably track flares or quiet spells. So once the result is known it rarely needs repeating. A number going up or down doesn't mean your treatment is failing or working, whatever the report looks like.
Disease activity gets followed with combined scores instead, built from joint counts, blood markers, and how you say you're doing. Those scores are what treatment decisions rest on. If somebody is reordering your anti-CCP, it's fair to ask what decision the new number would change, and a good answer is usually that it wouldn't.
Questions patients ask.
What does a positive anti-CCP result mean?
In someone with swollen, stiff joints it backs a diagnosis of rheumatoid arthritis hard, and here is why. The test clears 95 percent of people who don't have the disease, where rheumatoid factor clears only 85 percent, and a positive anti-CCP multiplies the odds of the disease by 12.46, which is a large move. On its own, in someone with no symptoms and a normal exam, it isn't a diagnosis and shouldn't be treated as one.
Can you have rheumatoid arthritis with a negative anti-CCP?
Yes, and about a third of people do. The test catches 67 percent of cases, so roughly one in three people with the disease test negative, which doctors call seronegative disease. It gets diagnosed four other ways, on your symptoms, on which joints are involved, on scans, and on your blood markers of inflammation. Left untreated it causes the same damage as the antibody-positive kind.
How is anti-CCP different from rheumatoid factor?
They catch almost the same share of cases, at 67 percent against 69 percent, and where they part company is in clearing healthy people. Anti-CCP clears 95 percent while rheumatoid factor clears only 85 percent. So rheumatoid factor turns positive far more often in other illnesses, in healthy people, and increasingly as people age. That difference is the whole reason anti-CCP counts for more in the diagnostic rules.
Does a positive result predict how bad my disease will be?
It says something about that without predicting anything for you in particular. One review looked at four studies, and three of them found joints wearing away faster on X-ray in the anti-CCP group than in the rheumatoid factor group. So a rheumatologist seeing a positive result in early joint symptoms will usually treat faster and harder. That moves the odds rather than telling you what will happen.
Should the anti-CCP test be repeated?
Rarely, because the antibody level doesn't reliably track how active your disease is. A number going up or down doesn't mean your treatment is failing or working, whatever it looks like on the report. Disease activity gets followed a different way, using combined scores built from joint counts, blood markers, and how you say you're doing. Once the result is known, repeating it seldom changes anything.
Can anti-CCP be positive before symptoms start?
Yes, sometimes by years, though not everyone who has these antibodies goes on to get rheumatoid arthritis. So the test belongs with a doctor looking at your whole situation rather than being ordered on a hunch. A positive result in someone with no symptoms brings real worry and no clear next step, and that's a genuine cost of testing without a question in mind.
References.
- Nishimura K; Sugiyama D; Kogata Y et al. Meta-analysis: diagnostic accuracy of anti-cyclic citrullinated peptide antibody and rheumatoid factor for rheumatoid arthritis. Annals of internal medicine. 2007;146:797-808. 10.7326/0003-4819-146-11-200706050-00008Diagnostic accuracy meta-analysis
- Whiting PF; Smidt N; Sterne JA et al. Systematic review: accuracy of anti-citrullinated Peptide antibodies for diagnosing rheumatoid arthritis. Annals of internal medicine. 2010;152:456-64; W155-66. 10.7326/0003-4819-152-7-201004060-00010Diagnostic accuracy systematic review and meta-analysis of 151 studies
This page gathers the published research on this subject into one place. The studies behind it were published between 1989 and 2026, and every figure links to the paper it came from. Those studies were peer reviewed. This summary of them was not. Dr. Sarah Luebker is reviewing these pages one at a time and has not reached this one yet, so it carries no medical review date and nothing here is her opinion or her advice to you. Each page gets updated as she reaches it. It is here in the meantime because the science is worth having in one organized place that is easy to find and easy to read. Talk to your own clinician before acting on any of it.