Objectives: To determine the predictive factors of clinical response to infliximab in patients with refractory psoriatic polyarthritis.
Methods: Multicenter open study which included 69 patients with psoriatic polyarthritis refractory to methotrexate (15 mg/week at least for 8 weeks). Patients were treated with infliximab 5mg/Kg every 8 weeks in addiction to their stable doses of methotrexate. A major clinical response was defined by the ACR 50 at week 38. Logistic regression analysis was performed to analyze which of the following parameters at the start of treatment were associated with an ACR50 response: demographic and clinical characteristics, duration of disease, tender and swollen joint counts, involvement of large joints (knee and/or hip), ESR, CRP, HAQ disability index, axial involvement and presence of erosions at baseline.
Results: In an intention-to-treat analysis 44% of patients achieved an ACR50 response. In the univariate analysis both the presence of large joints involvement and severe disability were associated with a poor clinical response. In a multivariate logistic regression analysis high CRP values was independently associated to a good therapeutical response (OR=18.7; 95% CI = 1.8- 181.6, p=0.011). In contrast, large joint involvement and severe disability were associated with a poor response, although only for large joint involvement reached statistical significance (OR=29.3; 95% CI= 3.2- 266.3, p=0.003).
Conclusion: A lower disability and mainly the lack of large join involvement and higher CRP serum levels at the start of the infliximab treatment seem to be factors that influence the probability to achieve a good therapeutical response in psoriatic arthritis patients.
- clinical response
- predictive factors
- psoriatic arthritis