Expert Tips on Diagnosing and Treating Psoriatic Arthritis

More than eight million Americans have psoriasis, and of those, up to 30 percent develop psoriatic arthritis, according to the National Psoriasis Foundation. While less common, psoriatic arthritis also can occur in people without skin psoriasis, particularly in those who have relatives with psoriasis.

With psoriatic arthritis, the immune system does not function properly. Instead of fighting off bacteria and viruses, it attacks the body’s tissues. Patients with this particular autoimmune disease may experience pain, stiffness, and swelling due to inflammation in the joints.

Psoriatic arthritis has similar symptoms to other types of arthritis, and several therapies are available that can help patients achieve low disease activity.

To better understand how to identify psoriatic arthritis and what treatments are currently used, Everyday Health posed some commonly asked questions to two experts in the field: John Miller, MD, instructor of medicine in the division of rheumatology at the Johns Hopkins University School of Medicine in Baltimore, and Stanford Shoor, MD, a rheumatologist with Stanford Health Care in Palo Alto, California.

Everyday Health's Expert Q&A

Everyday Health: How difficult is it to diagnose psoriatic arthritis and why is it challenging?

Dr. Shoor: It is somewhat difficult to diagnose psoriatic arthritis because it can appear as if it’s rheumatoid arthritis, osteoarthritis, or on some occasions gout.

The first thing you look for are skin manifestations (red or pink scaly skin). You look on the scalp, elbows, kneecaps, and front of the shins. Some have small patches on the cleft of the buttocks or inside the ear.

The second thing you look for is what we call dactylitis. Either a finger or toe becomes swollen through its entire length — not just in one joint. It’s commonly referred to as a sausage digit because it has that appearance of a sausage. You rarely see that in the other forms of arthritis.

Up to 60 or possibly 70 percent of people with psoriatic arthritis will test positive for the antigen HLA-B27 [which indicates a higher than average risk for autoimmune diseases].

Dr. Miller: In addition, you look at family history of psoriasis, nail changes, and asymmetrical distribution of arthritis. Psoriatic arthritis is suspected in patients with distal joint involvement [it often starts in joints closest to the fingernails and toenails], typical radiographic changes [such as signs of bone erosion or abnormal thickening revealed on X-rays], and negative rheumatoid factor. [Rheumatoid factor is an antibody commonly found in the blood of people with rheumatoid arthritis but not in those with psoriatic arthritis.]

Inflammatory back pain, lower back pain associated with prolonged morning stiffness and improvement with activity, may also be a clue for developing PsA.

Shoor: Ultimately, an examination by a rheumatologist and symptoms described by the patient will determine if you have psoriatic arthritis.

EH: How difficult is it to treat psoriatic arthritis? What are the typical approaches?

SS: We provide treatment based on the severity of the disease. We say to ourselves, “Is that person’s psoriatic arthritis at present minimal, mildly active, moderately active, or severe?” Those are not formal categories that every rheumatologist uses, but that’s the way I think of it and others do.

If people have barely any pain at all, you may not treat them with any drug if possible. If their pain level is a little higher — a 2 or 3 ­— you might offer them a nonsteroidal anti-inflammatory drug, such as Advil (ibuprofen) or Aleve (naproxen).

JM: Mild to moderate peripheral disease is often treated with disease-modifying anti-rheumatic drugs (DMARDs), such as methotrexate (Rheumatrex, Trexall) or leflunomide (Arava). Moderate to severe disease, refractory disease [meaning conventional options are ineffective at treating the pain] or axial disease [causing significant and chronic inflammatory low back or buttock pain] often favors the use of injectable biologic medication. [Biologics are also called immunomodulator therapies and include Humira (adalimumab) and Enbrel (etanercept)]. Patient preference and comorbidities (other diseases the patient may have) also play a significant role.

SS: There are other agents that may help, such as Actemra (tocilizumab), Xeljanz (tofacitinib), Cosentyx (secukinumab), and Otezla (apremilast).

At some points, patients may also use corticosteroids. You don’t rely on them for long-term use because of their side effects, but they can be used intermittently or temporarily while you’re waiting to see if other agents worked. All the other therapies mentioned will take between one and three months to be effective and in some cases a little longer that that.

For many people with psoriatic arthritis and psoriasis, the skin disease is worse than or as bad as the joint disease, and they will be treated by a dermatologist and rheumatologist in collaboration.

EH: Does the increase in medical options help or cause further confusion?

JM: These options are largely helpful. While there are several options for treatment, we are still learning how to appropriately pair the right medication with the right patient. Defining subsets of patients with psoriatic arthritis will be important for this. For example, patients with axial disease (in the low back) respond differently to DMARD therapies compared with patients with peripheral disease (in the arms and legs), and patients with predominant entheseal disease (affecting connective tissue between tendon or ligament and bone) may respond better to particular immunosuppression.

SS: Pharmacologic treatment is complex and can be confusing, but the chances are if left untreated, the result in the future will be irreversible joint damage, deformity, or disability. There is an art to how much you modify or reduce the immune system to keep it from attacking itself but also allow it to continue to fight against infections.

EH: How does treatment have to evolve over time?

JM: Treatment typically evolves with disease activity. When the disease remains quiescent for an extended period of time, we may be able to taper or discontinue medication. However, PsA sometimes becomes active or the medication becomes less effective and may require a change of therapy to regain disease control.

EH: Are there lifestyle changes and nonpharmacologic solutions that can help with psoriatic arthritis symptoms?

JM: Obesity and metabolic syndrome are particularly common in the setting of PsA and can decrease efficacy of specific medications. Weight loss, exercise, and diet are important interventions that can help improve arthritis outcomes.

SS: Exercise is extremely important to maintain the surrounding muscles, ligaments, and range of motion of a joint. You have to talk to your doctor about which kind of exercises you can do. You don’t want to do anything that causes you to pay for it the next day.

Stress always lowers the pain threshold, so you want to address stress the best you can.

There is no arthritis diet that is known to be superior to any nonarthritis or regular diet. Fish oil is known to be an anti-inflammatory. If you were going to say anything to people, it would be eat more fish.

In terms of herbs, curcumin — the main active ingredient in turmeric — has caught on. It’s anti-inflammatory to a degree but not powerfully anti-inflammatory.

As for nontraditional treatments outside of Western medicine, acupuncture has been the most popular and tends to give more pain relief than placebo.

The overarching principle with the nonpharmacologic therapies is if they feel 25 percent better and patients feel no harm, then it’s worth it.

EH: Are there other health concerns to be aware of related to psoriatic arthritis?

JM: Inflammatory arthritis is associated with increased risk of cardiovascular disease. As PsA is also associated with obesity and metabolic syndrome, there may be further cardiac risk. It is important to control the inflammation with medication; but diet, exercise, and weight loss are also very important from a cardiac perspective.

EH: Are there new treatments in the pipeline that you’re excited about?

JM: There are several biologic medications in the pipeline for PsA. There is a very interesting trial in Denmark [pre-results were published in April 2018 in the journal BMJ Open] studying the efficacy of fecal microbial transplantation in patients with PsA. If this intervention is successful, this could offer an entirely different mechanism to treat PsA.

SS: Most of the things in the pipeline are kinase inhibitors or Janus kinase (JAK) inhibitors. (These drugs inhibit the function of certain enzymes that play a role in inflammation and autoimmune diseases.) There are other biologic agents that are under development and show promise. If any patient wants to look at what’s in development, they can go to ClinicalTrials.gov.

EH: What are the most important messages you stress when it comes to the treatment of psoriatic arthritis?

JM: Communication is a crucial aspect of treatment. We have several effective medications, but it is not uncommon to make changes because of inefficacy, side effects, or cost. An open line of communication is helpful for facilitating these changes.

SS: For the person who has psoriatic arthritis, you want to reduce the pain at the present and you want to improve their quality of life and prevent damage in the future — and there are many different ways to go about doing that.

In the modern era of the last twenty years, we can tell most patients if they have psoriatic arthritis; and we have very effective treatments, so we’re optimistic that we can control your disease.