Table 2.

Estimated rate ratios of OP, SP and OB and of their product terms from modified Poisson regression, along with indexes of additive interaction between OP, SP and OB

Adjusted Relative rates (RR) for each exposure group from our modified Poisson regression
Exposure	Rate ratio (RR), 95% CI
None	Reference
OP only	1.24 (0.83, 1.87)
SP only	2.53 (1.95, 3.29)
OB (high FMI) only	2.05 (1.58, 2.66)
Both OP and SP only (OSP)	2.82 (2.16, 3.68)
Both OP and OB only (OOB)	2.34 (1.69, 3.23)
Both SP and OB only (SOB)	2.58 (1.95, 3.41)
OP, SP and OB (OSO)	3.06 (2.28, 4.11)
Interactions between risk factors
Risk factors and their interactions	Rate ratio (RR), 95% CI	P-value
OP-SP interaction	0.90 (0.58, 1.37)	0.612
OP-OB interaction	0.92 (0.58, 1.46)	0.718
SP-OB interaction	0.50 (0.37, 0.67)	< 0.001
OP-SP-OB interaction	1.16 (0.69, 1.96)	0.569
Relative excess rate due to interaction (RERI)
	RERI, 95% CI
RERI2 (OP, SP | no OB)a	0.04 (-0.55, 0.64)
RERI2 (OP, OB | no SP)a	0.05 (-0.65, 0.74)
RERI2 (SP, OB | no OP)a	-1.00 (-1.67, -0.34)
RERI2 (OP, SP | OB)b	0.10 (-0.28, 0.48)
RERI2 (OP, OB | SP)b	0.08 (-0.19, 0.35)
RERI2 (SP, OB | OP)b	-0.68 (-1.49, 0.12)
RERI3 (OP, OB, SP)c	0.16 (-0.83, 1.14)

The modified Poisson regression model was adjusted for age, gender, race, diabetes, hypertension, IHD, stroke, CKD, cognitive impairment, smoking status and alcohol status

^aRERI₂(X1, X2 | X3 = 0) = RR_X1+X2+X3+  − RR_X1+X2−X3- − RR_X1−X2+X3- + RR_{X1−X2−X3-}

^bRERI₂(X1, X2 | X3 = 1) = (RR_X1+X2+X3+  − RR_X1+X2−X3+  − RR_X1−X2+X3+  + RR_{X1−X2−X3+)} / RR_{X1−X2−X3+}

^cRERI₃(X1, X2, X3) = RR_X1+X2+X3+  − RR_X1+X2+X3−  − RR_X1+X2−X3+  − RR_X1-X2+X3+  + RR_X1+x2-X3- + RR_X1-X2+X3- + RR_X1-X2-X3+—RR_X1-X2-X3-