OBJECTIVE Although the influence of age on clinical and laboratory features has been widely demonstrated in many arthropathies, studies on elderly onset (> 60 years) psoriatic arthritis (EOPsA) are rare. This study compares manifestations at onset and two year outcome of EOPsA with those of younger onset PsA (YOPsA).

PATIENTS AND METHODS Sixty six consecutive PsA patients with disease duration < 1 year, 16 EOPsA (>60 years) and 50 YOPsA (⩽60 years) were admitted to a prospective study. Clinical, laboratory, and radiographic assessment were carried out at admission and after two years. HLA class I and bone scintigraphy were also recorded. In 10 patients with EOPsA and 24 with YOPsA it was possible to obtain synovial fluid, which was subsequently analysed for local inflammatory indices, including interleukin (IL) 1β, IL6, and IL8.

RESULTS Presenting manifestations of EOPsA differed from YOPsA in number of active joints (mean (SD)) (12.2 (6.3) v 6.7 (4.6), p<0.001), foot bone erosions (2.7 (1.2) v1.1 (1.1), p<0.001), erythrocyte sedimentation rate (64.2 (35.3)v 30.5 (30.0) mm 1st h, p<0.001), C reactive protein (3.9 (2.0) v 1.3 (1.3) mg/dl, p<0.001) and synovial fluid IL1β (8.0 (4.7)v 3.0 (3.0) pg/ml, p<0.001) and IL6 (828.2 (492.6) v 469.3 (201.4) pg/ml, p<0.005). No differences were found in the number of subjects with dactylitis, pitting oedema, HLA-B27, or signs of sacroiliac and sternoclavicular joint involvement at bone scintigraphy. After two years, progression was more evident in EOPsA than in YOPsA, as the number of new erosions in the hands and also the C reactive protein were higher in EOPsA patients.

CONCLUSION PsA has a more severe onset and a more destructive outcome in elderly people (onset >60 years) than in younger subjects. This behaviour may be influenced by immune changes associated with aging, as suggested by the higher concentrations of IL1β and IL6 found in the synovial fluid of EOPsA than in YOPsA.