Correlations between peripheral and axial radiological changes in patients with psoriatic polyarthritis

Peripheral radiological changes were investigated with respect to occurrence rates, severity and correlations with axial radiological change severity in a retrospective study in 140 patients with psoriatic polyarthritis. Study parameters were the number of erosions in joints of the hands and feet, severity of wrist lesions, sacroiliitis stage, number of syndesmophytes, number of pelvic and calcaneal enthesopathies and Larsen's damage score. Fifty patients had both peripheral changes and axial changes (bilateral stage 2 sacroiliitis or unilateral stage 3 or more sacroiliitis and/or syndesmophytes). Disease duration was correlated with radiological changes and the disease score. When patients were divided into quartiles based on polyarthritis duration, mean disease score was found to be significantly higher in the second than in the first quartile (p<0.005) and in the fourth than in the third quartile (p<0.0005), whereas the difference between the second and third quartiles was not significant. Peripheral changes progressed during the first five years of the disease. In contrast, the sacroiliitis score increased only in those patients with the longest disease durations. Correlations between severity of peripheral changes, sacroiliitis stage and disease score were found in all patients. In patients with axial lesions, peripheral involvement was more common and more severe and disease scores were significantly higher (p<0.00001). Our findings suggest that both peripheral and axial changes contribute to the severity of psoriatic polyarthritis and that the subgroup of patients with axial changes is characterized by more frequent and more severe peripheral lesions.