Table 5.

Adjusted risk of opportunistic infection in patients with rheumatoid arthritis (RA)

	Adjusted IRR (95% CI)	p Value
Current RA treatments
TNF antagonists	1.67 (0.95 to 2.94)	0.077
MTX	0.93 (0.54 to 1.60)	0.781
Prednisone	1.63 (1.20 to 2.21)	0.002
Other DMARDs	Reference	–
Clinical variables
Smoking history (ever)	1.64 (1.17 to 2.29)	0.004
Physician global assessment	1.01 (1.00 to 1.02)	0.027
Diabetes mellitus	1.88 (1.19 to 2.97)	0.027

The interaction term for MTX and TNF antagonist combination therapy was not significant (p = 0.876).

The multivariable model included demographic variables (age, gender, race and education level) as well as the treatment and clinical variables listed in the table. Other non-significant variables included were body mass index, ischaemic heart disease, chronic lung disease, duration of rheumatoid arthritis, ARA functional class, modified Health Assessment Questionnaire score, patient global score, patient pain score, swollen joint count, disability status, liver disorder and alcohol use.

DMARD, disease-modifying antirheumatic drug; IRR, incident rate ratio; MTX, methotrexate; TNF, tumour necrosis factor.