Table 2

Incidence rates and adjusted incidence rate ratios (IRRs) of myocardial infarction from Poisson regression analysis (overall estimates)

	General population	RA	DM	RA + DM	Test for difference RA versus DM^*
Myocardial infarction (n)	75 870	265	3,948	21
Time at risk (1000 person-years)	37 139	46	489	1.6
Mean follow-up time^† (years (SD))		4.6 (2.8)	3.9 (2.8)	3.0 (2.3)
Crude incidence (n/1000 person-years (CI))	2.0 (2.0 to 2.1)	5.7 (5.1 to 6.5)	8.1 (7.8 to 8.3)	13.0 (8.3 to 20.0)
Risk of myocardial infarction (IRR (CI))
Overall risk, gender-adjusted and age-adjusted	Reference	1.7 (1.5 to 1.9)p<0.001	1.9 (1.8 to 2.0)p<0.001	2.9 (1.9 to 4.4)p<0.001	p=0.06
Overall risk, fully adjusted^‡	Reference	1.7 (1.5 to 1.9)p<0.001	1.7 (1.6 to 1.8)p<0.001	2.6 (1.7 to 3.9)p<0.001	p=0.64

↵* Wald χ² test for difference of RA and DM IRR estimates.
↵† After entry into disease-specific group.
↵‡ Adjusted for gender, age, calendar year, cardioprotective medication, comorbidity and socioeconomic status.

DM, diabetes mellitus; RA, rheumatoid arthritis.