A 24 Week Open Label Study of the Utility of Adalimumab in Active Axial Forms of Psoriatic Arthritis

Inclusion Criteria: * Males and females aged between 18 and 70 years. * A negative pregnancy test for women of childbearing potential during the screening period. * Subject must be evaluated for active or latent TB (tuberculosis) infection by using a PPD skin test (Mantoux test), Booster test, chest x-ray and detailed review of subjetc´s medical history. * Subjects to whom the doctor has decided to prescribe adalimumab, because of fulfilling the requirements for this treatment. * Diagnosed with PsA according to CASPAR criteria. * Axial disease according to radiological criteria (at least unilateral sacroilitis grade II) and spinal inflammatory symptoms. * Disease duration of no less than 24 weeks * Patients with peripheral involvement (mixed forms of APs) must have been taking MTX for at least 12 weeks before screening and at stable doses of 10 to 25 mg/week for 8 weeks before screening, or salazopyrine up to 3 mg/daily, or cyclosporin 2mg/kg or leflunomide 20 mg daily in the same conditions as MTX. * Patient's doses of NSAIDs and oral corticosteroids (≤ 10 mg/day of prednisone or equivalent) should have been kept stable for 4 weeks before screening. Exclusion Criteria: * Contraindications for treatment with anti-TNF. * Prior treatment with other TNF inhibitors or other investigational drugs during the last 30 days (etanercept 4 weeks, infliximab 8 weeks). * Uncontrolled diabetes. * Uncontrolled high blood pressure. * Unstable ischemic heart disease. * Congestive heart failure. * Severe pulmonary disease. * Chronic leg ulcer. * History of cancer or malignant lymphoproliferative disease. * Positive serology for Hepatitis B indicating active infection or positive serology for Hepatitis C. * History of positive HIV status. * Persistent, recurrent or severe infections requiring hospitalization or treatment with oral antibiotics within 14 days prior to enrollment. * Previous diagnosis or signs highly indicative of central nervous system demyelinating diseases. * Active tuberculosis, histoplasmosis or listeriosis. * History or presence of confirmed blood dyscrasia. * Female subjects who are pregnant or breast-feeding. * History of clinically significant drug or alcohol abuse in the last year. * Treatment with MTX, salazopyrine, ciclosporin or leflunomide initiated within the last 4 weeks before the screening. Treatment with corticosteroids (\>10mg/day or equivalent or modified dose within the previous 4 weeks before screening). And patients where an intraarticular corticoid infiltration has been practised within the last 4 weeks before the screening will be excluded from the study. * Treatment with more than one NSAID within the last 4 weeks before the screening. * Patients treated with any DMARD different from MTX, cyclosporine, leflunomide and sulfasalazine. * Dosage of concomitant MTX, cyclosporine, leflunomide and sulfasalazine must be stable during the study, otherwise it should be properly justified and recorded in the case report form. * Patients treated with any analgesic different from acetominophen, NSAIDs, oxycodone, codeine, propoxyphene, tramadol, hydrocodone or combinations of these products or equivalents. The use of potent opioids is not permitted.