Predicting Erosion Risk in Psoriatic Arthritis

An analysis of records from the Toronto Psoriatic Arthritis Cohort concluded that baseline characteristics can help predict which patients will and will not develop erosions.

Investigators used data from 290 patients whose disease had been followed for at least 10 years and whose files contained radiographs. They scored the radiographs with the modified Steinbrocker method to determine which patients had developed erosions and used regression models to determine which initial characteristics — as recorded at each patient’s first visit to the clinic — were associated with erosion risk.

By the end of the study period, 87.6% of the patients exhibited erosions. Among those patients, the mean time to erosion development was 6.8 years ± a standard deviation of 6.1 years.

The remaining 12.4% of the study population remained erosion-free. Those 36 patients had been diagnosed with psoriatic arthritis at a significantly younger age (22.5 years ± a standard deviation of 14.7 years) than the other 254 patients (27.6 ± 12.1 years).

“Actively inflamed joints and clinically damaged joints were predictive of the development of erosion, whereas a longer duration of psoriasis at baseline decreased the odds of developing erosion. Erosion-present patients had a higher percentage of unemployment as compared with erosion-free patients at baseline and follow-up visits,” the study authors wrote in The Journal of Rheumatology.

“The clinical and radiographic findings can ultimately assist in the stratification of a patient’s prognosis regarding the development of erosions.”

Previous research has found other factors that contribute to bone erosion, the most important of which may be delayed treatment. A 2014 study that appeared in the Annals of the Rheumatic Diseases analyzed records from 283 patients with psoriatic arthritis and found, via multiple stepwise regression analysis, that a 2-year delay in treatment was associated with more than 4 times the peripheral joint erosions as a 6-month delay (odds ratio [OR], 4.25; p=0.001).

“Even a 6-month delay from symptom onset to the first visit with a rheumatologist contributes to the development of peripheral joint erosions and worse long-term physical function,” the authors of that analysis wrote.

Once treatment begins, progression of erosions tends to be very slow. A 2014 study of apremilast users published in the Scandinavian Journal of Rheumatology performed found no progression in 41 patients after 24 weeks of treatment.

Other studies have found, however, that some treatments slow the progression of erosions better than others. A 2013 study published in the Annals of the Rheumatic Diseases compared outcomes in 70 patients treated with methotrexate and 65 treated with tumor necrosis factor α (TNFα) blockers. Radiographs taken 1-2 years after baseline found progression of radiographic damage in 80% of patients who used methotrexate and 58.9% of patients who used TNFα blockers (p=0.005). Radiographs taken 3-4 years after baseline found progression of radiographic damage in 88% of patients who used methotrexate and 61% of patients who used TNFα blockers (p=0.005).

“In the multivariate regression analysis methotrexate treatment was associated with an increase in radiographic damage compared to TNFα blockers (p=0.001),” the study authors wrote.