Cohort study of the association of antibody levels to AMA1, MSP1 19 , MSP3 and GLURP with protection from clinical malaria in Ghanaian children

Table 3 Association of IgG2 and IgG4 with malaria incidence.

Antigen	Antibody		Crude IRR (95%CI)	P-value	Age-adjusted IRR	P-value
MSP3
	IgG2*	(coded as log(2))	0.74 (0.57, 0.98)	0.04	0.85 (0.63, 1.15)	0.29
	IgG4	< detection limit	1	0.01	1	0.20
		< median	0.45 (0.21, 0.95)		0.56 (0.26, 1.19)
		≥ median	0.47 (0.28, 0.79)		0.68 (0.40, 1.15)
MSP1 ₁₉
	IgG2*	(coded as log(2))	0.62 (0.45, 0.86)	< 0.01	0.836 (0.606, 1.157)	0.275
	IgG4*	(coded as log(2))	1.07 (0.95, 1.21)	0.25	0.838 (0.608, 1.159)	0.278
GLURP
	IgG2*	(coded as log(2))	0.65 (0.49, 0.86)	< 0.01	0.79 (0.58, 1.08)	0.13
	IgG4*	(coded as log(2))	0.94 (0.81, 1.08)	0.37	1.01 (0.87, 1.16)	0.94
AMA1
	IgG2	< detection limit	1	0.18	1	0.54
		< median	1.80 (0.86, 3.78)
		≥ median	1.78 (0.90, 3.51)
	IgG4	< detection limit	1	0.19	1	0.54
		< median	0.96 (0.47, 1.93)
		≥ median	0.62 (0.36, 1.07)

For IgG 2 to AMA1 and for IgG4 to AMA1 and MSP3, antibody level was categorized.
*For IgG2 to MSP3, MSP1₁₉ and GLURP, the association is expressed as the incidence rate ratio (IRR) corresponding to a doubling of baseline antibody level.