Background Pulmonary comorbidity (PC) is a clinically important complication in patients with rheumatoid arthritis (RA) because PC has been recognized as one of the prognostic factors for RA^1-3 and often prevents patients from receiving aggressive treatments for RA. Furthermore, Japanese may be more susceptible to development of PC than other ethnic groups⁴. However, a difference in risk factors for serious infections (SIs) between patients with and without PC has not been thoroughly studied yet.

Objectives To compare risk factors for SIs between patients with and without PC using the Registry of Japanese RA patients for Long-term safety (REAL) database.

Methods This study included Japanese RA patients who started biologics or nonbiological DMARDs at the enrollment in the REAL database. Case report forms were filed by attending physicians every 6 months up to 5 years for each patient in the REAL. Observation period of this study started at the enrollment in the REAL and was censored after 2 years. We analyzed types and incidence rates of SIs. Analysis included 360 patients with PC [PC group, 589 patient-years] and 1,384 patients without PC (non-PC group, 2,325 patient-years). PC included interstitial pneumonia (193), obstructive pulmonary diseases (30), bronchiectasis (20),and other pulmonary diseases. To identify risk factors and hazard ratio (HR) for SIs in each group, Cox proportional-hazard regression analysis was applied.

Results At baseline, patients were older (p<0.001) and percentage of male was higher (p<0.001) in the PC group. The PC group had higher DAS28 (3/CRP) (p<0.001) and poorer physical function (p<0.001), and received lower dosage of methotrexate (p<0.001). Percentage of patients receiving prednisolone (PSL) more than 7.5mg/day (p=0.001) and that of patients who had diabetes mellitus (DM) (p<0.001) were also higher in the PC group. There were 65 SIs (40 for pulmonary, 11 for skin and subcutaneous tissue, 14 other infections) in the PC group, and 89 SIs (42 for pulmonary, 21 for skin and subcutaneous tissue, 26 other infections) in the non-PC group. The crude incidence rate ratios comparing the PC group with the non-PC group were 2.8 (2.1-4.0) for all SIs and 3.7 (2.4-5.8) for pulmonary infections. Multivariate analyses revealed that age by decade (HR [95% CI], 1.8 [1.4-2.3]), presence of DM (1.9 [1.0-3.4]) and use of PSL ≥7.5mg/day (2.1 [1.2-3.7]) were significant risk factors for SIs in the PC group, while age by decade (1.5 [1.1-2.0]), Steinbrocker’s stage (III or IV) (1.9 [1.0-3.4]), and DAS28 (3/CRP) (1.4 [1.1-1.7]) in the non-PC group. HR of higher dosage of PSL in the PC group and those of biologics in both groups were not significant.

Conclusions Different risk factors were associated with SIs between RA patients with and without PC.

1. Rheumatology 2010; 49:1483-1489

2. Arthritis Rheum 2010; 62:1583-1591

3. Ann Rhum Dis 2010; 69:1086-1091

4. Nat. Rev. Rheumatol 2010; 6:644-652

Disclosure of Interest R. Sakai: None Declared, M. Tanaka: None Declared, T. Nanki: None Declared, H. Yamazaki: None Declared, K. Watanabe: None Declared, R. Koike: None Declared, N. Miyasaka Grant/Research support from: Abbott Japan Co., Ltd., Astellas Pharma Inc., MSD K.K., Chugai Pharmaceutical Co., Ltd., Daiichi Sankyo Co., Ltd., Eizai Co., Ltd., Janssen Pharmaceutical K.K., Mitsubishi Tanabe Pharma Co., Takeda Pharmaceutical Co., Ltd., and Teijin Pharma Ltd., Consultant for: Janssen Pharmaceutical K.K., Bristol Myers Squibb K.K., Otsuka Pharmaceutical Co. Ltd., Mitsubishi Tanabe Pharma Co., Abbott Japan Co., Ltd., M. Harigai Grant/Research support from: Abbott Japan Co., Ltd., Astellas Pharma Inc., Bristol Myers Squibb K.K., Chugai Pharmaceutical Co., Ltd., Eisai Co., Ltd., Mitsubishi Tanabe Pharma Co., Santen Pharmaceutical Co., Ltd, Takeda Pharmaceutical Co., Ltd., and Pfizer Japan Inc., Consultant for: Abbott Japan Co., Ltd., Astellas Pharma Inc., Bristol Myers Squibb K.K., Chugai Pharmaceutical Co., Ltd., Eisai Co., Ltd., Janssen Pharmaceutical K.K., Mitsubishi Tanabe Pharma Co., Santen Pharmaceutical Co., Ltd, Takeda Pharmaceutical Co., Ltd., and Pfizer Japan Inc.