Session Information
Date: Tuesday, November 7, 2017
Session Title: Rheumatoid Arthritis – Clinical Aspects Poster III: Comorbidities
Session Type: ACR Poster Session C
Session Time: 9:00AM-11:00AM
Background/Purpose: Serious infections (SI) in patients with rheumatoid arthritis (RA) are a perpetual concern. We compared the risk by first and recurrent SIs in patients with RA compared to those with non-inflammatory rheumatic diseases (NIRD) in a real-world setting.
Methods: Participants had RA or NIRD from1998 through 2016 in the National Data Bank for Rheumatic Diseases (NDB). NIRD included diagnoses such as osteoarthritis, back pain syndromes, tendonitis, etc; this comparator group helps minimize selection and reporting bias. SIs were defined as those requiring hospitalization or intravenous antibiotics, or leading to death. All SIs were described by etiology and location and were additionally categorized as opportunistic or herpes zoster when they occur. Survival analysis methods (Cox regression, time to first infection using time-varying covariates and Andersen-Gill multiple failures model) were applied, both in a univariate and multivariable manner. Confounders included demographics, comorbidities, disease severity measures and glucocorticoid (GC) use.
Results: There were 20,361 RA and 6,176 NIRD patients who contributed to 81,499 and 20,665 patient-years of exposure, having had 1,643 (7.9%) and 281 (4.5%) SIs, respectively. A higher proportion of RA patients with SI were younger, had worse HAQ scores, lower BMI, and a higher frequency of GC use and smoking compared to NIRD patients (Table 1). The most frequent SIs by etiology were bacterial and by location was respiratory in both groups. The incidence rate ratios (IRR) of the first and recurrent SIs for RA vs. NIRD were similar (1.5 [1.3 -1.7]). The IRRs for opportunistic infections and herpes zoster ranged between 2.2 – 3.3. The multivariable analysis showed a significant SI risk increase in RA patients compared to NIRD (HR 1.32 [1.15-1.52]). By etiology, the risk of bacterial infections was significantly higher in patients with RA than NIRD. Respiratory, bloodstream infections with sepsis, skin, bone and joint infections were also significantly increased in RA (Table 2).
Conclusion: The risk of SIs, particularly bacterial, respiratory, blood stream, skin and joint infections is increased in RA patients compared to NIRD patients. The increased risk could be explained by immune dysregulation caused by the disease itself, comorbid conditions or medications. A limitation of this study is that there was a significant proportion of SIs that were not categorized by type or location in medical records. Further studies collecting detailed SI information and the impact of medications would be needed to accurately describe the risk of SIs in RA.
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Table 1. Mean (SD) baseline characteristics of all RA and NIRD patients and by serious infections |
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All |
|
Serious Infections |
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|
RA |
NIRD |
P-value |
RA |
NIRD |
P-value |
|
|
N |
20,361 |
6,176 |
|
1,643 |
281 |
|
|
Age, yrs |
58.2 (13.7) |
62.8 (13.4) |
<0.001 |
66.6 (12.0) |
71.7 (11.9) |
<0.001 |
|
Male, % |
20.3 |
19.6 |
0.223 |
25.1 |
22.1 |
0.279 |
|
White, % |
94.3 |
96.6 |
<0.001 |
94.6 |
95.7 |
0.449 |
|
BMI, kg/m2 |
28.9 (7.1) |
29.4 (7.4) |
<0.001 |
28.4 (7.5) |
30.5 (8.4) |
<0.001 |
|
Urban vs Rural, % |
26.9 |
23.9 |
<0.001 |
32.3 |
25.2 |
0.018 |
|
Education, yrs |
13.6 (2.4) |
13.6 (2.4) |
0.210 |
13.3 (2.3) |
13.7 (2.3) |
<0.001 |
|
Smoking History, % |
41.5 |
34.9 |
<0.001 |
50.6 |
40.6 |
0.002 |
|
Disease duration, yrs |
14.1 (12.5) |
15.6 (13.5) |
<0.001 |
19.7 (12.8) |
21.9 (15.1) |
0.010 |
|
Comorbidity index (0-9) |
1.8 (1.6) |
1.9 (1.6) |
<0.001 |
2.5 (1.8) |
2.6 (1.6) |
0.650 |
|
HAQ (0-3) |
1.1 (0.7) |
1.1 (0.7) |
0.300 |
1.3 (0.7) |
1.2 (0.7) |
<0.001 |
|
Pain (0-10) |
4.2 (2.9) |
4.2 (2.9) |
0.900 |
4.5 (2.8) |
4.7 (2.9) |
0.260 |
|
Patient global (0-10) |
3.8 (2.6) |
3.8 (2.5) |
0.940 |
4.3 (2.5) |
4.1 (2.5) |
0.450 |
|
Diabetes, % |
8.6 |
8.9 |
0.520 |
13.9 |
17.7 |
0.094 |
|
Glucocorticoid use, % |
28.3 |
4.43 |
<0.001 |
47.4 |
9.3 |
<0.001 |
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Table 2. Incidence Rate Ratio (IRR) and Multivariable Hazard Ratios (HR) (95%CI) of serious infections by Etiology location |
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|
Infection |
IRR first Infection |
Multivariable HR first infection* |
IRR recurrent Infection |
Multivariable HR recurrent infection* |
|
All infections |
1.5 (1.3-1.7) |
1.3 (1.2-1.5) |
1.5 (1.4-1.7) |
1.3 (1.2-1.5) |
|
Opportunistic infections |
3.0 (1.4-7.7) |
1.9 (0.8-4.2) |
3.3 (1.5-8.4) |
1.9 (0.9-4.3) |
|
Herpes zoster |
2.2 (0.9-6.2) |
1.8 (0.7-4.4) |
2.4 (1.0-6.8) |
1.9 (0.8-4.7) |
|
Bacterial infections |
1.6 (1.3-2.0) |
1.4 (1.2-1.8) |
1.6 (1.4-1.9) |
1.4 (1.1-1.6) |
|
Viral infections |
1.5 (0.9-2.6) |
1.3 (0.7-2.2) |
1.5 (0.9-2.5) |
1.2 (0.7-2.0) |
|
Fungal infections |
5.1 (1.3-43.3) |
3.0 (0.7- 2.9) |
5.4 (1.4-46.3) |
2.9 (0.7-12.6) |
|
Unknown cause |
1.4 (1.2-1.7) |
1.3 (1.1-1.5) |
1.4 (1.2-1.7) |
1.3 (1.1-1.5) |
|
Respiratory |
1.4 (1.2-1.7) |
1.4 (1.1-1.6) |
1.5 (1.3-1.7) |
1.3 (1.1-1.6) |
|
CNS |
1.4 (0.4-7.5) |
1.3 (0.4-5.0) |
1.5 (0.4-7.9) |
1.3 (0.4-4.8) |
|
Abdominal |
2.0 (1.0-4.3) |
1.4 (0.7-2.8) |
1.9 (1.0-3.9) |
1.3 (0.7-2.6) |
|
Urinary |
0.8 (0.4-1.5) |
0.7 (0.4-1.3) |
0.9 (0.5-1.6) |
0.7 (0.4-1.3) |
|
Bloodstream infections including sepsis |
1.8 (1.3-2.5) |
1.6 (1.1-2.2) |
1.8 (1.4-2.5) |
1.6 (1.2-2.2) |
|
Skin, bone and joint infections |
1.5 (1.2-1.9) |
1.3 (1.0-1.7) |
1.5 (1.2-1.8) |
1.3 (1.0-1.6) |
|
Unknown type |
2.6 (1.2-6.2) |
1.8 (0.8-3.8) |
2.7 (1.3-6.6) |
1.8 (0.9-3.9) |
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*Multivariable Cox proportional hazard model adjusted for age, sex, race, HAQ, pain scale, rheumatic diseases comorbidity index, education level, residency (urban vs rural), glucocorticoid use, prior serious infections and smoking status |
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To cite this abstract in AMA style:
Mehta BY, Pedro S, Ozen G, Michaud K. Serious Infection Risk in Patients with Rheumatoid Arthritis Compared to Patients with Non-Inflammatory Rheumatic Diseases: A US National Cohort Study [abstract]. Arthritis Rheumatol. 2017; 69 (suppl 10). https://acrabstracts.org/abstract/serious-infection-risk-in-patients-with-rheumatoid-arthritis-compared-to-patients-with-non-inflammatory-rheumatic-diseases-a-us-national-cohort-study/. Accessed October 3, 2022.« Back to 2017 ACR/ARHP Annual Meeting
ACR Meeting Abstracts - https://acrabstracts.org/abstract/serious-infection-risk-in-patients-with-rheumatoid-arthritis-compared-to-patients-with-non-inflammatory-rheumatic-diseases-a-us-national-cohort-study/