Psoriatic arthritis is a relatively common condition affecting between 15-30% of us with psoriasis (although rarely it can feature without skin involvement).

The things that interest me most about psoriatic arthritis are:

1/ How often it is misdiagnosed (it’s much more wiley than Rheumatoid Arthritis)

2/ Whether immediate treatment with methotrexate is necessary

So I interview Consultant Rheumatologist Dr Laura Coates, a Rheumatologist and a research scientist whose research interests focus on diagnosis and treatment of psoriatic arthritis. In this article, you will find the summary of our conversation but you can of course listen to the whole thing on The Psoriasis Geek Podcast here:

What is the difference between Rheumatoid and Psoriatic arthritis?

“ If you have psoriasis the chances are that you have psoriatic arthritis…

I have a very small number of patients who have both rheumatoid and psoriatic arthritis and we are convinced they are separate things. The genetics behind them are quite different.”

Dr Laura Coates, Consultant Rheumatologist

I have had periods where I have been concerned that I have psoriatic arthritis in my finger joints, and Dr Coates was keen to acknowledge that not all joint paint is psoriatic arthritis. Some of her referrals are wear and tear related such as osteoarthritis, and can be caused by mechanical joint pain – from lifting kids for example. She explains that in older men it’s not uncommon for symptoms to be attributable to gout.

So when looking at symptoms, what should we look for?

Dr. Coates says that “Rheumatoid presents with a much more typical pattern and it typically comes on much more quickly – so patients suddenly notice a big change and usually there’s quite a lot of swelling in the hands as well, so they push for a referral to their G.P.

Psoriatic arthritis can be more variable – so it can be just one or two joints, and it can move around.

It can be outside the joints, it can be tendons that are affected, and often they are painful but the G.P can’t find a swollen joint and is not sure what it is – so that’s not picked up well and therefore is not referred that quickly.

It can be a much milder disease – come and go and not bother people too much, in which case they just get used to living with it.”

Swelling in fingers due to psoriatic arthritis – thanks Russ for the photo 🙂

Research in 2018 backs this up. 203 patients were asked about their diagnosis experience and while 51% of these were diagnosed with a year – there was notable variability amongst the remaining 49% with some waiting over ten years for an accurate diagnosis. (1)

The misdiagnosis for psoriatic arthritis reported amongst the people included anxiety and depression, back problems (you will see why in just a mo’), fibromyalgia, orthopaedic problems, osteoarthritis and psychosomatic disease.

Why is psoriatic arthritis so under-diagnosed?

1. People ignore it.

Sometimes the symptoms are really mild, and sometimes there is a trigger for the flare which can be used to explain away the symptoms.

Some examples of this from my life include;

2. The G.P misses the signs and symptoms

“Often G.Ps will minimise it because they are used to common things being common,” says Dr Coates. And I get that – I have heard myself minimise my own symptoms in the doctor’s surgery.

The symptoms may not present as ‘typical’ for arthritis if there is no swelling in the joint to observe, plus this incredibly important fact:

“If you have psoriasis, the risk is that you have psoriatic arthritis. There is no blood test for psoriatic arthritis that works.

Dr Laura Coates, Consultant Rheumatologist

The blood tests your G.P may refer you for to test for arthritis will come up negative if you have psoriasis arthritis.

This means if you have psoriasis AND arthritic symptoms you must push for a referral to a rheumatologist.

How is Psoriatic Arthritis Diagnosed?

If your G.P doesn’t have the tools to diagnose you – then what happens when you get to rheumatology?

In the NHS, new patients are referred to an early arthritis clinic.

You then see a consultant for a joint inspection, review of your medical history and a discussion around your symptoms.

Ultrasound is used to help to visualise the joints. An x-ray can be useful for more advanced arthritis but for early-stage psoriatic arthritis, ultrasound has several advantages.

“Ultrasound can look beyond the bones, it can look inside the joints, inside the tendons and see if there’s inflammation in there.”

Dr Laura Coates, Consultant Rheumatologist

If you are like me, and your symptoms wax and wane then don’t worry, I asked about whether a diagnosis can still be made if things aren’t as bad as normal on clinic day.

Dr Coates said “We can see thickening in the joint, or thickening in the tendon.” so we don’t need to worry there, as long as the symptoms are recent. A good reason not to put off asking for a referral.

Can lifestyle affect the onset and severity of psoriatic arthritis?

We all know that a healthy lifestyle is good for our health, but as we love a good fad I thought I would check-in and find out if any of them had made a significant impact on Dr Coates patients.

Unsurprisingly Dr Coates highlights that “Smoking is bad for your joints and your psoriasis” – with cigarette smoke containing over 2,000 toxins I can’t help but agree. She also highlights challenges with obesity – difficulty in measuring the effectiveness of treatments because the drug effectiveness is assessed by measuring pain, function and movement. All of these parameters are affected by obesity.

Do I need to take Methotrexate/ drugs to treat this?

Dr Coates is used to being asked this question, and it is not easily answered.

“Establishing prognosis in psoriatic arthritis is probably the hardest thing for us to do, at least in individuals. And obviously, that’s what matters if you’re the patient.

X rays often do not pick up inflammation and damage to tendons seen in psoriatic arthritis.

We know overall, that patients have less X ray damage than patients with rheumatoid arthritis – but they actually have a similar impact on the quality of life, and that’s either because:

We have patients with mutilations type arthritis, which is pretty rare. But when patients get really significant damage to the bones, often developing shortening of their fingers and toes because the bones are damaged so much – obviously, that can have a massive impact on them function long term.

But then we have a lot of patients who have either no or very mild damage to the bones, and if they continue like that, it’s a lot less of a concern.

So overall, the stuff that we know, that can be useful is that the more joints you have that are inflamed – the worse your prognosis, so the more you potentially need treatment.

If you have high inflammation markers on your blood test, which 50% of psoriatic arthritis patients never have, then that increases your risk of damage.

If you have marked functional disability at the beginning, if you’re really struggling to do day to day things like opening car doors, cutting your meat, you know – the normal things that we ask about in clinic, that’s a poor prognostic factor.

And if you have damage at baseline; so if you’ve had the disease for quite a short period of time, and you have x rays at your first visit, and you already have evidence damage, that’s probably the biggest predictor of you’re going to get more damage.

So we have to kind of use that limited information to try and translate that for an individual and say, How much do you need to take treatment? Or how much can we relax about this? And it’s that balance of treating symptoms now. So making you feel better and be able to go to work and do your normal life, and improving your joint pain and potentially your psoriasis as well. And also your long term outcome. So if you can manage with it now, do you store up any problems in the future?”

What should you ask at your initial consultation?

Where is my inflammation?

In psoriatic arthritis, your inflammation can be in your joints, tendons and spine.

“Between 25 to 50% of patients have involvement in their spine, that can be tricky to spot and they often ignore it because back pain is normal – and an MRI may be needed for diagnosis as you cannot see a swollen back joint.”

What treatments are recommended?

Feel free to question whether you actually need to take it – and ask about the risks if you do not, and the side effects if you do.

“There are some patients with mild disease where I explain…. We don’t know much about patients with mild disease, they’re not very well studied – we think your chances of developing damage is pretty low, your symptoms are pretty mild, if your managing day to day with a painkiller, doing regular exercise, sometimes people find diet helpful, the I am happy to watch and wait.”

It is not unreasonable to expect your consultant to discuss non-pharmaceutical interventions with you, but you may need to push for that conversation if that’s the route you want to take.

Just don’t be pig-headed – if your rheumatologist is explaining that you already have damage, your blood tests show high CRP (C-reactive protein) and there is a poor prognosis without intervention I would listen to their expert opinion and if your not happy find a second opinion before trying a new diet. Not all joint damage is reversible. You can always wean yourself off the medication under supervision once your improved lifestyle factors are in place.

Treat to Target (and the truth about methotrexate).

Treat to target is a new initiative which is being trialled in an NHS clinic in Oxford. It is based upon the use of rigorous assessments to ensure that treatments are effective.

If you’re like me and answer ‘fine’ to the question; Are you ok? Even though I really am not then this is the way forwards.

Instead of relying on our poor self-assessments of our symptoms (we often weight how ok we are against ut last flare and not against life ‘before’), doctors use multiple questionnaires and scanning techniques to measure progress, and not just physically – but our mental health and our quality of life assessments are core to this approach as well.

I thought this would mean that lower doses of drugs could be used as follow up is so through but instead, it turns out that the dose of methotrexate is sometimes higher and I now understand why:

“I’m a great believer in reasonable doses of methotrexate – because I think people give up too soon or think that it hasn’t worked – you need a reasonable dose to test it. It’s probably a higher dose than you need for Rheumatoid arthritis, it’s probably a higher dose than you need for psoriasis as well.

Where a moderate dose is 15mg, but escalated quickly if people tolerate it to give them the best chance of responding within a 12-week window.”

I have to admit – I feel a little less hostile about higher doses of MTX now … as long as once symptoms are resolved my Rheumatologist is happy experimenting with lower doses.

What are the alternatives to Methotrexate (MTX)?

“The aim is to try and make [the treatment]  fit the individual. And for the most part, we follow a similar protocol, at least to start with – we can be flexible on what the first drug is if methotrexate isn’t appropriate  (that is our most commonly first line drug).

Whether we switch or combine with different medications and what our second drug very much depends on the patient and on the risks and other diseases that they might have, such as liver problems.

Biologics, obviously, we do get to and we use particularly in patients with spinal disease a lot earlier as well, and to be honest, because of the drop in cost with Adalimumab that happened back in November that tends to be our first line for everybody, because it’s so much cheaper.

And for the Arthritis component, there’s no evidence yet of one [biologic] being better than another, all of them get pretty similar outcomes. And that’s obviously different to skin psoriasis, where certain drugs have been shown to be obviously better than others. And we don’t have that in the biologics and psoriatic arthritis. We nearly always use the TNF inhibitor Adalimumab as the first line, but then we can switch to other drugs or use other drugs first line if there’s a reason they can’t.”

Criteria for access to Biologic treatment for Psoriatic Arthritis

Cimzia is one of the Biologics that may be used.

“Our rules in the UK are that you have to have at least three tender and three swollen joints, and you have to have failed to standard drugs. So that’s usually methotrexate and one other one.

The only exception to that is spinal arthritis. So if you have significant arthritis in your spine, doesn’t respond to methotrexate or any of the other tablets that we have you jumped straight to biologics. So for that, you have to have a spinal pain scores of over four out of 10. And you have to have failed to standard anti-inflammatories, so drugs like ibuprofen, that kind of thing.”

In the U.S access is based on state-specific legislation and insurance cover but access often follows a similar model to the N.H.S (as it’s based on a cost-benefit analysis). Speak to The National Psoriasis Foundation for more State specific advice on access.

How to get the most from your Rheumatology appointment

1/ Tell the truth

ompare your symptoms against your life BEFORE. Do not compare against your last flare. Make sure you also talk about the impact on your relationships and social life. They are important too.

2/ Write down your questions.

As Dr X says “everybody always forgets them”. Yep! Before I wrote down my questions I always kicked myself afterwards for forgetting to ask something…usually before I made it to the steps back to reception.

3/ Ask about your issues.

“Be open if you’re worried about taking a drug, I’d much rather you tell me than say you’ll take it and then go home and not take it….Tell me and I can talk you through it”

Your doctor wants to know so tell them.

I used to lie about how often I took my meds – that’s also not helpful either. Tell your doctor the truth! I’m pretty sure they can’t scold you….

4/ Know what you want to get out of it

Where do you want to be?

What is your target?

My dermatologist struggled to comprehend that my target isn’t to be clear of psoriasis. I just want to not itch. Know exactly what you want to achieve, and make it clear to your doctor – you can then work together to develop a more holistic approach if you want to be able to paint again for example, or go to the world cup and be able to jump out of your seat periodically.

About Dr Laura Coates

Laura is a Consultant Rheumatologist and an NIHR Clinical Scientist who is researching optimal therapeutic strategies for patients with psoriatic arthritis (PsA).

She is also a member of the Steering Committee of the Group for Research and Assessment of Psoriasis and Psoriatic Arthritis (GRAPPA) and the British PsA Consortium (BritPACT).  She is the first author on the 2015 GRAPPA treatment recommendations for psoriasis and PsA and is also involved in the GRAPPA/OMERACT initiative to refine the core set of outcome measures for PsA.


All quotes are DrX taken from the podcast interview available on iTunes/stitcher/spotify and via the player embedded in this page 🙂

Ogdie, A. Nowell, W et al (2018) Diagnostic experiences of patients with psoriatic arthritis: misdiagnosis is common. 77:2 Annals of Rheumatic Disease accessed 10/05/2019