People with psoriatic arthritis may have low bone mineral density, but the link remains unclear
Psoriatic arthritis (shortened to PsA) is a chronic inflammatory disease that affects a person’s joints, causing pain and disability. The disease often causes swelling of the fingers and toes. It gets its name from the link between this type of arthritis and a skin condition called psoriasis, which causes redness and scaling. Most people lose bone density as a normal part of ageing. Osteoporosis is a condition where a person’s bone density is reduced, making their bones fragile and more likely to fracture (break). Hip, spine (back) and wrist fractures are the most common types of fracture in people with osteoporosis.
WHAT DID THE AUTHORS HOPE TO FIND?
The authors wanted to find out whether people with psoriasis or psoriatic arthritis are more likely to have low bone mineral density, osteoporosis or fractures. They also hoped to be able to show if there is a genetic link between psoriasis and osteoporosis.
WHO WAS STUDIED?
The study looked at samples from 4,904 people with psoriasis and 847 people with psoriatic arthritis.
HOW WAS THE STUDY CONDUCTED?
This was an observational study. This means that the authors looked at existing information stored in UK Biobank databases. There was no intervention being tested. 4,904 people with psoriasis and 847 people with or psoriatic arthritis were identified from over 400,000 medical records. From these data the researchers could test if these people developed low bone mineral density or osteoporosis.
WHAT WERE THE MAIN FINDINGS OF THE STUDY?
The main finding was that psoriatic arthritis might be a risk factor for low bone mineral density, but the link was not genetically determined. The analysis suggest that other factors such as treatment with methotrexate or ciclosporin might reduce bone mineral density. Having reduced physical activity due to arthritis also had an important effect. No difference in bone mineral density was found between people with psoriasis (no arthritis) and people without the disease.
ARE THESE FINDINGS NEW?
Yes. They found that psoriasis by itself is not a risk factor for osteoporosis. For people with psoriatic arthritis, the link is still unclear.
WHAT ARE THE LIMITATIONS OF THE STUDY?
One limitation is that people’s bone mineral density was estimated by a type of imaging called quantitative ultrasound, but a different technique called dual-energy X-ray absorptiometry (DXA for short) might work better. In addition, the authors did not have access to all information about the disease activity of people with psoriasis.
WHAT DO THE AUTHORS PLAN ON DOING WITH THIS INFORMATION?
The authors would like to do further studies using DXA to check the association between psoriatic arthritis and bone mineral density. They would also like to investigate how methotrexate affects bone.
WHAT DOES THIS MEAN FOR ME?
If you have psoriatic arthritis and receive treatment with methotrexate or ciclosporin, you might be more at risk of developing osteoporosis. Your doctor might suggest checking your bone mineral density. You can take steps to improve your bone health by doing regular exercise and eating a healthy, balanced diet. To find out the best options for you, talk to your doctor.
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Date prepared: October 2020
Summary based on research article published on: 31 July 2020
From: Xia J, et al. Systemic evaluation of the relationship between psoriasis, psoriatic arthritis and osteoporosis: observational and mendelian randomization study. Ann Rheum Dis 2020;79:1460–1467. doi: 10.1136/annrheumdis-2020-217892.
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