Background/Purpose

Psoriatic arthritis could lead to severe damage and disability. However, cases of improvement in joint damage over time have been reported in the literature.  We aimed to determine the prevalence of  damage reversal in a large cohort of patients with psoriatic arthritis and to identify predictors of this unique feature. 

Methods

In a cohort of PsA patients established in 1978, radiographic assessments are made every two years with readings by at least 2 investigators. A consensus rating according the modified Steinbrocker scoring (mSS) method classifies each of 42 hand and foot joints on a 0-4 scale where grade 0=normal, 1= juxtaarticular osteopenia or soft tissue swelling, 2= erosion, 3= erosion and joint space narrowing and 4=total destruction. Reversal of damage was defined as a decrease in the total mSS confirmed on second reading.  Disease characteristics of the study population were presented using descriptive statistics. A transitional multistate model was applied to investigate ratios of transition intensities in the Steinbrocker staging of each joint, with a working independence assumption used for joints within the same patient. A reversible Markov model was applied to investigate predictors for damage reversal and progression including age, sex, disease duration , the number of actively inflamed joints at baseline and treatment with MTX and biologics in the course of follow up.

Results

Of 537 PsA patients with baseline and at least 1 follow-up radiographs with all available data 56.2% were males, had a mean (SD) age of 43.7 (12.7) and disease duration of  7.0 (8.3) years. 32.4% and  66.9% were treated with DMARDs and biologics, respectively. 373 patients developed at least 1 damaged joint. 117/537 patients (21.8%) had evidence of reversal in damage in at least one joint. Of the20,307 assessed joints in 537 patients, 339 joints had  improvement in damage, of whom the majority 213 out of 348 transitions were from mSS 2 to 1 and had an intensity score of 0.025 (0.022, 0.029) as apposed to the highest estimated progression rate of 0.061 (0.055, 0.067). 164 joint improvement occurred before treatment with biologics in  63 patients, of whom the majority 104/168 transitions were also from mSS 2 to 1. When analyzing the data on the 89,965 patient-joint assessments, treatment with biologics was a predictor for transition to a state of joint improvement (RR=2.25 (1.79,2.83) P< 0.0001) and less for joint progression (RR=0.67 (0.61,0.74) P< 0.0001). 

Conclusion

A number of patients have reversal in damage (21.8%), which occurred in 1.7% of the assessed joints.  Treatment with biologics is a predictor for joint improvement and less progression of damage. Transitions of joint improvement were observed also in patients not treated with biologics.