Arthritis & Rheumatism, Volume 63,
November 2011 Abstract Supplement
Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Chicago, Illinois November 4-9, 2011.
The Incidence of Infection in Psoriatic Arthritis - Results From a Longitudinal Observational Cohort.
Haddad1, Amir, Thavaneswaran2, Arane, Chandran1, Vinod, Gladman2, Dafna D.
Toronto Western Hospital and University of Toronto, Toronto, ON
Toronto Western Hospital, University of Toronto, Toronto, ON
Background/Purpose:
Many patients with psoriatic arthritis are treated with biologic agents. The main adverse event is infection. However, the rate of infection among patients with psoriatic disease is unknown. The purpose of this study was to investigate the rate, type and characteristics of illness in patients with psoriatic arthritis (PsA) in contrast to a control group of patients with psoriasis without arthritis (PsC).
Methods:
The PsA cohort was initiated in 1978. Patients are followed at 6–12 month intervals according to a standard protocol which includes history, physical examination laboratory evaluation and radiographic assessment. It collects documentation of the presence, site and type of infection at each visit. In 2006 a cohort of patients with PsC was initiated. Patients with psoriasis are all assessed by a rheumatologist to exclude the presence of inflammatory arthritis, and are followed at yearly intervals according to the same standard protocol. Data are tracked in a computerized database. Descriptive analyses were conducted using t tests and chi-square tests. Only infections observed after 2006 were included.
Results:
695 patients with PsA and 511 patients with PsC and were followed up in our respective clinics since 2006. A total of 607 infections were detected among 318 patients with PsA, and 176 observed infections among 144 patients with PsC. The incidence rate of infection was similar in both groups with 0.33 (95% CI 0.31, 0.36) per patient-year in the PsA cohort and 0.29 (95% CI 0.25, 0.30) per patient-year in the PsC cohort (p=0.15). The incidence rate of infection for patients on biologics was higher at 0.44 (95% CI 0.39–0.50) and 0.66 (95% CI 0.39–1.04) in the PsA and PsC cohorts respectively. Patients with PsA were more likely to have 4 or more infections during the course of follow-up compared to patients with PsC (p=0.0001). Among patients with PsA the most common infections were lung, sinus, skin (cellulitis) and upper respiratory whereas among PsC patients skin, genitourinary, lung and upper respiratory were most prevalent. Patients with PsA had less bacterial infections compared to PsC (62% vs. 77.1% p=0.005), and were less likely to have been treated with antibiotics than patients with PsC (73.6% vs. 87.1% p=0.0003). Patients with PsA and PsC with infection shared similar background comorbidities. In the PsA group patients were older (51.8 vs. 46.7 yrs, p=0.0002) and as expected required more treatment with NSAIDs, DMARDs and biologics (p<0.0001), while patients with PsC were more likely to be treated with phototherapy (p<0.0001). Patients with PsA had a lower prevalence of smoking and alcohol consumption than patients with PsC (p=0.0002 and 0.0015, respectively).
Conclusion:
The incidence rate of infection was similar in PsC and PsA cohorts at 29–33 infections per 1000 patient-years. Patients with PsA suffered from recurrent infections more commonly than patients with PsC. Patients in the two cohorts were more likely to have a bacterial etiology for infection and required in the majority of cases antibiotic treatment. The most commonly reported infection was pneumonia in the PsA group and cellulitis in the PsC group.
To cite this abstract, please use the following information:
Haddad, Amir, Thavaneswaran, Arane, Chandran, Vinod, Gladman, Dafna D.; The Incidence of Infection in Psoriatic Arthritis - Results From a Longitudinal Observational Cohort. [abstract]. Arthritis Rheum 2011;63 Suppl 10 :1651
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