Trauma Flagged as Trigger for Arthritis in Psoriasis Patients

Pam Harrison

July 02, 2015

ROME — Patients with psoriasis who experience bone or joint trauma have a significantly higher risk for psoriatic arthritis than patients not exposed to such trauma, a population-based cohort study suggests.

In fact, patients with psoriasis who experienced trauma had a 32% higher risk of developing psoriatic arthritis than nontrauma control subjects, said Thorvardur Love, MD, from Landspitali University Hospital in Reykjavik, Iceland.

Bone trauma led to a 46% increase in the risk for psoriatic arthritis, and joint trauma led to a 50% increase.

In contrast, psoriasis patients who had experienced nerve or skin trauma were at no higher risk for psoriatic arthritis than their nontrauma counterparts.

"This is the first sizable population-based cohort study to determine the risk of psoriatic arthritis following trauma in psoriasis patients," Dr Love said during a news conference here at the European League Against Rheumatism Congress 2015.

"Given the high baseline risk of developing psoriatic arthritis among patients with psoriasis, bone and, in particular, joint trauma have a very large impact on the absolute risk of developing psoriatic arthritis," he explained.

For their matched-cohort study, Dr Love and his team used the Health Improvement Network database from 1995 to 2013 to identify participants.

The study cohort involved 15,416 patients with psoriasis who had been exposed to some form of trauma and 55,230 patients with psoriasis who had not been exposed to trauma and who served as the control subjects.

Patients exposed to trauma were randomly matched to five unexposed control subjects for sex, age, and the date of entry in the database.

Patients were stratified into subgroups by type of trauma — joint, bone, nerve, and skin.

On average, patients were followed for about 6 years, for a total of 425,120 person-years of follow-up. During the follow-up period, investigators documented 1010 cases of psoriatic arthritis.

The crude results showed that the incidence of psoriatic arthritis was higher in the trauma group than in the control group (30 vs 22 per 10,000 patient-years of follow-up).

A multivariate Cox model, adjusted for confounding variables, demonstrated that psoriasis patients exposed to trauma still had a higher risk of developing psoriatic arthritis than control subjects.

Table. Effect of Trauma on Risk for Psoriatic Arthritis

Trauma Hazard Ratio 95% Confidence Interval
All 1.32 1.13–1.54
Bone 1.46 1.04–2.04
Joint 1.50 1.19–1.90

 

In an identical analysis that used the same database, the risk of developing rheumatoid arthritis was similar in patients without psoriasis who experienced trauma and those who did not (hazard ratio, 1.04; 95% confidence interval, 0.99 - 1.10).

"It's not going to be very helpful to say to people, 'don't get hurt,' because people don't usually intend to get hurt," Dr Love told Medscape Medical News.

"However, perhaps now that we know that trauma is a risk factor for psoriatic arthritis, we can start thinking about ways to modify the risk once trauma happens by, for example, treating patients earlier with an alternative therapy," he explained.

"We're not there yet, but even if we can't prevent trauma, this is about where we could take this and where we might actually be able to have an effect," he added.

Dr Love has disclosed no relevant financial relationships.

European League Against Rheumatism (EULAR) Congress 2015: Abstract OP0311. Presented June 13, 2015.

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