Quantification of the dynamics of antibody response to malaria to inform sero-surveillance in pregnant women

Malaria Journal

Table 2 Multivariate linear mixed-effects modelling of the combined IgG responses (measured as optical density (OD) values) to Plasmodium falciparum and Plasmodium vivax recombinant antigens

Variable	PfAMA1	PfEBA175	PfMSP2	PfMSP3	PvAMA1	PfVAR2CSA
Fixed effects^a
Age (years)	0.001 (− 0.006, 0.008)	0.007 (− 0.001, 0.015)	0.005 (− 0.001, 0.01)	0.001 (0.0001, 0.003)	− 0.001 (− 0.002, 0.0004)	0.003 (− 0.0001, 0.007)
Gravidity
Primigravidae	0.064 (− 0.05, 0.179)	− 0.017 (− 0.153, 0.118)	0.013 (− 0.075, 0.102)	0.004 (− 0.018, 0.027)	− 0.005 (− 0.029, 0.02)	− 0.012 (− 0.069, 0.046)
Intervention group
Chloroquine	0.054 (− 0.021, 0.13)	0.048 (− 0.041, 0.136)	0.009 (− 0.05, 0.067)	− 0.003 (− 0.019, 0.013)	0.019 (0.002, 0.036)	0.031 (− 0.007, 0.069)
History of malaria
Yes	− 0.04 (− 0.116, 0.036)	− 0.024 (− 0.113, 0.065)	− 0.02 (− 0.08, 0.039)	− 0.002 (− 0.018, 0.013)	0.012 (− 0.005, 0.028)	− 0.014 (− 0.053, 0.024)
Average random effects for a woman
Low immune
Mean antibody level^b	0.31 (0.231, 0.388)	0.469 (0.373, 0.564)	0.704 (0.631, 0.777)	0.069 (0.048, 0.09)	0.095 (0.073, 0.117)	0.235 (0.189, 0.281)
Gestation (weeks)^c	− 0.001 (− 0.002, 0.0001)	− 0.002 (− 0.003, − 0.0004)	− 0.003 (− 0.004, − 0.001)	0.00004 (− 0.001, 0.001)	− 0.0003 (− 0.001, 0.0003)	− 0.001 (− 0.002, 0.0004)
High immune
Mean antibody level^b	0.864 (0.67, 1.062)	1.076 (0.897, 1.264)	1.000 (0.893, 1.111)	0.603 (0.404, 0.808)	0.448 (0.283, 0.608)	0.634 (0.498, 0.766)
Gestation (weeks)^c	− 0.0004 (− 0.006, 0.005)	0.0001 (− 0.005, 0.005)	0.001 (− 0.002, 0.005)	− 0.006 (− 0.012, − 0.001)	− 0.003 (− 0.008, 0.002)	0.002 (− 0.003, 0.006)

Posterior medians (95% credible interval) for the fixed effects, population average intercept and population average slope parameters
^aFixed effects interpretation: change in mean antibody levels per year increase in age and difference in mean antibody levels for primigravidae vs. multigravida (reference group), chloroquine vs. placebo (reference group) and history vs. no history of malaria (reference group)
^bPopulation mean antibody levels for women of average age (25 years old), multigravida, in the placebo group and with no history of malaria
^cPopulation average change in antibody levels for a one week increase in gestation

ISSN: 1475-2875