Unadjusted generalised estimating equation Poisson analysis for infections
| Outpatient infections (N=2223) | Hospitalised infections (N=59) | |
|---|---|---|
| Estimated IRR (95% CI) | Estimated IRR (95% CI) | |
| 5-Unit change in CDAI | ||
| If CDAI <10 | 1.22 (1.13 to 1.31)*** | 2.07 (1.27 to 3.35)** |
| If CDAI ≥10† | 1.01 (0.97 to 1.04) | 1.05 (0.88 to 1.25) |
| DAS28 (0.6 units) | 1.09 (1.06 to 1.12)*** | 1.32 (1.10 to 1.60)** |
| Age (10 years) | 0.92 (0.89 to 0.96)*** | 1.29 (1.04 to 1.61)* |
| Female | 1.39 (1.23 to 1.58)*** | 0.75 (0.42 to 1.34) |
| Current smoker | 0.99 (0.85 to 1.14) | 0.68 (0.29 to 1.61) |
| Married | 1.05 (0.94 to 1.17) | 1.39 (0.74 to 2.60) |
| Caucasian | 0.95 (0.82 to 1.11) | 0.81 (0.37 to 1.78) |
| College education | 1.09 (0.98 to 1.21) | 0.69 (0.39 to 1.22) |
| BMI | 1.01 (1.003 to 1.02)** | 1.05 (1.02 to 1.08)** |
| Private insurance | 1.12 (1.0 to 1.26) | 0.66 (0.38 to 1.16) |
| Medicaid insurance | 1.0 (0.79 to 1.26) | 3.03 (1.36 to 6.78)** |
| Medicare insurance | 0.91 (0.82 to 1.00) | 2.02 (1.17 to 3.51)* |
| History of CVD | 1.23 (1.01 to 1.49)* | 3.11 (1.55 to 6.26)** |
| History of infections | 2.74 (2.47 to 3.03)*** | 2.9 (1.60 to 5.27)*** |
| History of hospitalised infections | – | 16.2 (8.00 to 32.80)*** |
| Disabled | 1.36 (1.18 to 1.56)*** | 2.79 (1.54 to 5.07)*** |
| Severity of RA | 1.00 (0.96 to 1.05) | 1.53 (1.18 to 1.97)** |
| Duration of RA (10 years) | 1.01 (0.96 to 1.06) | 1.38 (1.11 to 1.72)** |
| HAQ disability index | 1.22 (1.09 to 1.37)*** | 3.17 (2.09 to 4.79)*** |
| No methotrexate use‡ | 1 | 1 |
| Methotrexate <15 mg/week | 1.16 (1.02 to 1.32)* | 0.69 (0.33 to 1.44) |
| Methotrexate ≥15 mg/week | 1.09 (0.96 to 1.24) | 1.0 (0.54 to 1.86) |
| No prednisone use‡ | 1 | 1 |
| Prednisone <7.5 mg daily | 1.1 (0.96 to 1.25) | 1.9 (0.99 to 3.64) |
| Prednisone ≥7.5 mg daily | 1.09 (0.81 to 1.47) | 13.56 (7.2 to 25.54)*** |
| TNF inhibitor | 1.29 (1.17 to 1.43)*** | 0.7 (0.40 to 1.21) |
| Other DMARD | 0.87 (0.78 to 0.97)* | 1.13 (0.65 to 1.97) |
| ACR functional class I‡ | 1 | 1 |
| ACR functional class II | 1.45 (1.32 to 1.60)*** | 2.5 (1.32 to 4.73)** |
| ACR functional class III | 1.31 (1.07 to 1.55)** | 4.2 (1.87 to 9.45)*** |
| ACR functional class IV | 1.47 (0.96 to 2.24) | 18.78 (7.12 to 49.52)*** |
↵* p<0.05,
↵** p<0.01,
↵*** p<0.001.
↵† Additional infection risk at clinical disease activity index (CDAI) ≥10 when compared with low CDAI (<10).
↵‡ Baseline category.
ACR, American College of Rheumatology; CVD, cardiovascular disease; DAS28, disease activity score 28; DMARD, disease-modifying antirheumatic drug; HAQ, health assessment questionnaire; IRR, indicent rate ratio; RA, rheumatoid arthritis; TNF, tumour necrosis factor.