3 Reasons Why Psoriatic Arthritis Can Be Difficult to Diagnose

While we at Bezzy are dedicated to psoriatic arthritis, it doesn’t always receive the same awareness and recognition elsewhere.

Psoriatic arthritis (PsA) is an inflammatory form of arthritis. The disease affects about 1.5 million Americans, and it can lead to progressive joint pain, joint damage, and loss of function.

One of the most effective ways of preventing disease progression and joint damage is early diagnosis and treatment. But according to a 2021 study, the average diagnosis of PsA takes about 2.5 years from the onset of symptoms, with an overall range of 6 months all the way up to 7 years.

The research also found there were 3 groups more likely to experience a delay in diagnosis:

• those with a higher body mass index (BMI)
• those under 40 years old
• those experiencing enthesitis (inflammation at the site where ligaments and tendons attach to bone)

Although the effect on quality of life and functional ability of PsA can be similar to that of rheumatoid arthritis (RA), it lacks the same awareness and recognition — even by physicians, which plays a role in diagnosis time.

There are a few key factors that make PsA difficult to diagnose and can contribute to this disparity in diagnosis time.

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A lack of reliable tools for PsA screening

There’s no one specific blood or imaging test that rheumatologists can order. Rather, doctors will use various tests to help eliminate other causes.

When it comes to blood work for PsA diagnosis, rheumatologists can determine if there’s inflammation in the body by checking your C-reactive protein and erythrocyte sedimentation rate (ESR). This lets them know if it’s inflammatory autoimmune arthritis or osteoarthritis.

From there, the doctor will further narrow things down by checking for rheumatoid factor, an autoantibody usually produced by patients who have RA, but not by those who have PsA.

A rheumatologist might also send a patient for imaging such as an X-ray, MRI, or CT scan. This is done in order to assess the kind of joint damage and inflammation present. The results can help point toward which type of arthritis it is.

Joint fluid could also be used as an assessment, with the presence of uric acid crystals indicating gout rather than PsA.

So, while there are tests that can be done to aid diagnosis, it’s often a process of elimination because there’s no straightforward test for PsA.

Misconceptions about psoriasis involvement

Another reason PsA goes undiagnosed is due to misconceptions about psoriasis involvement. Having psoriasis is not as reliable of a clue as you might think.

About 7.5 million Americans have psoriasis, but only around 30 percent of these people develop PsA. In addition, patients with psoriasis can develop other types of arthritis, such as gout or osteoarthritis.

It’s also possible to develop joint pain and inflammation caused by PsA before experiencing psoriasis symptoms. It’s rare, with only 14.7 percent of patients receiving a PsA diagnosis before that of psoriasis, but it can occur.

Typically, those who fall within that small percentage have a family history of psoriasis. This is why doctors should always do a thorough family medical history when assessing for PsA.

Additionally, some patients might have psoriasis that goes unnoticed. Mild psoriasis of the scalp or inverse locations, such as the ears or belly button, can often be disregarded as dry skin.

So, although there’s a strong connection between psoriasis and PsA, the presence or lack of psoriasis is not always the determining factor in a PsA diagnosis.

PsA is a master of disguise

PsA can not only mimic other forms of arthritis and health conditions, but it also has multiple forms itself, each presenting differently.

The 5 types of PsA are:

• Symmetric PsA. This affects five or more joints on both sides of your body, most commonly affecting your hands and feet.
• Asymmetric PsA. Typically impacting less than five joints in your body, this is called “asymmetrical” because the joint symptoms only occur on one side of the body.
• Distal interphalangeal predominant PsA. This impacts the end joints of your fingers and toes and often occurs along with other types of PsA.
• Spondylitis PsA. This causes inflammation in the axial joints, such as the spine, which can cause pain and stiffness in the neck, lower back, and sacroiliac joints.
• PsA mutilans. The most severe type of PsA, mutilans can deform and destroy the joints in your fingers, hands, wrists, and feet. It’s rare, occurring in less than 5 percent of people with PsA.

To further add to the confusion, patients can have multiple forms of PsA simultaneously.

The intricacy of PsA makes it hard to be conclusive about a diagnosis, especially in its early stages. For example, when it’s isolated to one joint, PsA can appear as tendonitis and be passed off as a sports injury.

Alternatively, if a patient has low back pain, the doctor may suspect it’s just a mechanical cause from day to day activities, like lifting, or they could blame it on weight.

Having at least one misdiagnosis prior to being diagnosed with PsA is very common, frequently mistaken as:

• psychosomatic disease
• osteoarthritis
• anxiety
• depression

These periods of misdiagnosis are not only harmful to a patient’s physical symptoms, but they can also cause emotional distress.

Going forward

PsA is complex and impacts each patient differently, making the diagnosis process frustrating. This can lead to a long process of elimination and disease progression due to lack of diagnosis, or often misdiagnosis, and improper treatment.

There is a definite lack of awareness and understanding of the disease as a whole, in the medical field and beyond. No one should have to suffer in pain for years from a disease for which there are plenty of treatments available.

Thankfully, in recent years PsA has been getting more attention. However, there’s clearly more to be done, and raising awareness and recognition of the chronic condition is one way of reducing diagnosis times. This is something that we can all do.