Psoriatic arthritis

The arthritis comes from an immune system that inflames tissue it should leave alone. Its targets are the joints and the tissue around them, the spine, and the entheses, where tendons and ligaments grip the bone. Along with axial spondyloarthritis and reactive arthritis, it belongs to the spondyloarthritis family, and the three have a number of features in common.

It has no one cause. An inherited make-up that leaves someone open to it, often with psoriasis or a related condition somewhere in the family, combines with triggers that are not yet understood. Most of the people who get it have psoriasis already, though in some the joints are affected before the skin. Smoking, carrying extra weight and an injury to a joint or tendon are all linked with it. It affects men and women in roughly equal numbers, and it usually starts between 30 and 50.

Psoriatic arthritis shows itself in several ways, and the mix differs from one person to the next. Look out for:

• Sore, swollen joints, whether the fingers, the toes, the knees or elsewhere
• A whole finger or toe puffed up along its length, so that it looks like a sausage
• Pain where a tendon is anchored, at the heel or the back of the elbow, say
• Aching in the back or deep in the buttocks, if the spine is affected
• Changes in the nails, small pits or a nail lifting away, often together with psoriasis on the skin

No blood test proves psoriatic arthritis, so the diagnosis rests on the whole picture: your symptoms, any psoriasis of your own or in your relatives, the examination and suitable tests.

Ultrasound has a lot to offer in psoriatic arthritis, because it can show inflammation in the tendons and where they attach, and in the joints too, and can find it early on. Point-of-care ultrasound is part of the consultation with Dr Borukhson, so this can often be checked during the same appointment. The ultrasound clinic page describes the scan in more detail.

Treatment has three goals: to bring the inflammation down, to ease the symptoms and to protect the joints and tendons, with the skin kept in view throughout. Your treatment is planned for you and talked through fully, and as in other inflammatory arthritis, effective treatment begun early serves you best in the long run.

Several kinds of medicine can settle the overactive immune response. A disease-modifying anti-rheumatic drug (DMARD), such as methotrexate, sulfasalazine or leflunomide, is often where treatment starts. When the joints, the spine or the tendons stay inflamed, a biologic or targeted medicine, such as one that blocks TNF or the action of a messenger called interleukin-17, is the next option, picked with an eye on the skin, since some of them help psoriasis as well. A specialist supervises all of these: methotrexate needs regular blood tests, a biologic needs screening before the first dose because it can make an infection likelier, and where pregnancy may come into it, the treatment is planned around it. Methotrexate damps down the immune system, so it can make an infection likelier, as a biologic can. Your team revisits the plan at each review. For a joint or tendon that stays sore despite treatment, an ultrasound-guided injection may help. You agree to any treatment before it starts.

What you do between appointments makes a difference. Keeping active helps: regular, gentle movement keeps the joints supple and loosens stiffness, and stretching alongside it looks after the tendons and their attachments, which this condition tends to reach.

• Get to a healthy weight and stay there, which takes strain off the joints and can help some medicines work better
• Stop smoking, since it makes both the psoriasis and the arthritis worse and weakens the response to treatment
• Balance rest and movement during a flare, rather than stopping altogether
• Look after your skin and nails, and tell your team when they flare, as in some people the skin and the joints flare together

The chance of a heart condition is somewhat higher with psoriatic arthritis over the years, as in other inflammatory arthritis. Of the things that lower that risk, holding the inflammation down is among the most useful; our guide to inflammation and your heart lists the simple checks to ask your GP or your team about.

The outlook is good for most people. With treatment started early and checked carefully, the condition is usually kept well in hand, though it tends to last, and is managed over the years rather than cured.

Most changes in the skin, the nails or the joints can be left for your next review, or for a GP appointment if you are not yet under a team. The signs in the lists below cannot wait, and they start with the most serious; the paragraph after the lists names those for your team or GP within days.

Treat any of these as a 999 or A&E emergency: call 999 and do not drive yourself to A&E.

• Severe illness with suspected sepsis: a high fever with shaking, confusion, rapid breathing, or feeling dramatically worse over hours
• With a fever or feeling unwell, a rash that does not fade when you press it, a stiff neck with eyes that cannot bear bright light, or skin, lips or tongue turning blue, grey, pale or blotchy, since these can be signs of meningitis or sepsis; on black or brown skin the rash and the change of colour may be easier to see on the palms of the hands or the soles of the feet
• Chest pain that is crushing, tight or like a pressure, that spreads to an arm, the jaw, the neck, the stomach or the back, that comes with breathlessness, sweating, feeling sick or feeling light-headed, or that came on suddenly and does not go away
• Sudden weakness or numbness on one side, a drooping face or difficulty speaking, a sudden severe headache, sudden confusion or a seizure, or sudden loss of vision, any of which can be a stroke, even if it stops after a short time, and psoriatic arthritis makes a stroke somewhat likelier
• An eye that suddenly and completely loses its sight
• Lips, mouth, throat or tongue that suddenly swell, a throat that feels tight, very fast breathing or a struggle to breathe or to swallow, skin, tongue or lips turning blue, grey or pale (on black or brown skin this may be easier to see on the palms of the hands or the soles of the feet), becoming suddenly very confused, drowsy or dizzy, or fainting and not being able to be woken, since this can be a severe allergic reaction, anaphylaxis, which can follow a dose of any medicine

Any of these needs an assessment that is urgent, on the same day, from your GP, your rheumatology team or NHS 111:

• A fever, or feeling generally unwell, on immunosuppressant, biologic or steroid treatment, since an infection has to be treated early; on these medicines a fever can be an infection rather than a flare, which is why it is checked that day
• A joint that is hot and swollen, with a fever or feeling unwell, since an infected joint has to be ruled out at once, at A&E or through NHS 111
• A joint that has become hot and very swollen suddenly, or is worsening quickly, even without a fever, since an infected joint does not always announce itself with one; a joint that will take no weight at all, or that cannot be moved, is a 999 or A&E emergency, whether or not there is a fever
• A new red, painful eye, or sight that has blurred, dimmed or changed, which needs an eye casualty or urgent eye clinic the same day, as does an eye that light hurts, since psoriatic arthritis can bring on inflammation inside the eye, which can damage the sight for good if it is left untreated; our uveitis guide describes it
• Being near someone with measles, chickenpox or shingles, while you take a medicine that weakens the immune system, since measles and chickenpox can be dangerous when the immune system is weakened, and you can catch chickenpox from someone with shingles if you have never had chickenpox; NHS 111 can tell you what to do that day

Short of the signs in the lists above, a joint that has newly swollen but is not hot, or that has become much more painful, a finger or toe that swells along its length, or fresh pain in the back, the buttocks or a heel, should be reported to your rheumatology team, or to a GP if no team looks after you yet, to be seen within days, since the condition may be active, or just beginning, and treatment may need starting or changing. Anything else that is severe, sudden or leaves you feeling very unwell should not wait for a routine appointment: anything that could be life-threatening is a 999 or A&E emergency, so call 999 and do not drive yourself to A&E, and NHS 111 can say where to go if you are not sure. If your spine is affected, our axial spondyloarthritis guide lists the back's own warning signs where it says when to seek help. If you cannot tell how urgent something is, asking is never a mistake.

Caught early, psoriatic arthritis can usually be controlled well and the harm to the joints kept small. NICE points out that the signs of spondyloarthritis, the family psoriatic arthritis belongs to, are not always recognised outside specialist clinics, and that the substantial delays in diagnosis and treatment that can follow let the disease progress and cause disability. If you have psoriasis, joints that start aching or swelling, or a heel or tendon that turns painful, it is worth a specialist's opinion within days, through your GP or booked directly, even when the symptoms seem slight.

I have psoriasis and my joints hurt. How quickly do I need to be seen?

Within days: see your GP, who can refer you, or book a specialist assessment directly. NICE advises that anyone thought to have psoriatic arthritis is referred to a rheumatologist as soon as it is suspected, and that people with psoriasis are checked for it once a year, most of all in the first ten years of the skin condition. In this family of conditions, a diagnosis or treatment that comes late can let the disease advance and cause disability, so early treatment gives the joints their best chance.

Could I have it if my skin is barely affected, or not affected yet?

Yes. Arthritis can start long after the skin first showed psoriasis, and once in a while before any rash has appeared. Psoriasis in the family and changes in the nails, small pits or a nail lifting away from its bed, count as well, which is why the assessment looks at the whole picture and not just the skin.

What does Dr Borukhson check at the first appointment?

Dr Borukhson goes over your history, asking about psoriasis in you or your relatives, and examines your joints and spine and the spots where tendons fix to the bone, the heel among them. Point-of-care ultrasound is part of the consultation with Dr Borukhson, and in psoriatic arthritis it is especially useful, since it can show an inflamed tendon or tendon attachment early.

Does treating the arthritis do anything for my psoriasis?

It can. Some of the biologic medicines used for the arthritis treat psoriasis too, so the skin is weighed alongside the joints and tendons when a treatment is chosen. Your plan is reconsidered as time goes on, and nothing is changed without your agreement.

What checks does the treatment need?

It depends on the medicine. Methotrexate means regular blood tests, and a biologic is only started after screening, because it can leave you more open to infection. If pregnancy is a possibility, the treatment is chosen to suit it, and your follow-up visits keep the plan up to date.