Plasmodium falciparum antigenic variation: relationships between widespread endothelial activation, parasite PfEMP1 expression and severe malaria

Table 1 Age-adjusted logistic regression models predicting (A) impaired consciousness and (B) cerebral malaria (N = 213)

	A: impaired consciousness		B: cerebral malaria
Models	Explanatory variables	OR (95% CI)	P value	OR (95% CI)	P value
1$	Group A-like	4.5(1.7,11.4)	0.002	2.97(1.14, 7.76)	0.026
2	ang-2	3.0(1.9, 4.7)	0.000002	2.52(1.57, 4.03)	0.00012
3$	Parasite density (peripheral)	1.37(1.12, 1.67)	0.002	1.46(1.16, 1.84)	0.001
4	PfHRP2	1.34(1.13, 1.60)	0.001	1.43(1.17, 1.74)	0.0004
5$	IE surface antibodies	0.96(0.94, 0.98)	0.00002	0.96(0.94, 0.99)	0.001
6	Group A-like	3.5(1.32, 9.44)	0.012‡	2.3(0.84,6.33)	0.1
6	ang-2	2.82(1.78, 4.46)	0.000009‡	2.38(1.48, 3.82)	0.0003‡
7$	Group A-like	2.3(0.86, 6.3)	0.097	1.73(0.63, 4.77)	0.3
7$	IE surface antibodies	0.96(0.94, 0.98)	0.0001‡	0.97(0.95, 0.99)	0.003‡
8	ang-2	2.87(1.76, 4.66)	0.00002‡	2.35(1.43, 3.85)	0.001‡
8	IE surface antibodies	0.96(0.94, 0.98)	0.00007‡	0.97(0.95, 0.99)	0.003‡
9$	Group A-like	4.15(1.6, 10.7)	0.003‡	2.65(0.99, 7.08)	0.05
9$	Parasite density (peripheral)	1.3(1.1, 1.65)	0.005‡	1.43(1.14, 1.81)	0.002‡
10	Group A-like	4.24(1.6, 11.21)	0.004‡	2.68( 0.98,7.37)	0.05
	PfHRP2	1.32(1.12, 1.57)	0.001‡	1.40(1.15, 1.71)	0.001‡
11	ang-2	2.7(1.7, 4.3)	0.00005‡	2.17(1.33, 3.53)	0.002‡
11	Parasite density (peripheral)	1.21(0.97, 1.5)	0.09	1.32(1.04, 1.68)	0.023‡
12	ang-2	2.6(1.60, 4.24)	0.005‡	2.07(1.24, 3.44)	0.005‡
	PfHRP2	1.18(0.98, 1.41)	0.080	1.28(1.04,1.58)	0.019‡

The analysis in this table considers the outcomes IC and CM as factors, which means non-IC/CM severe cases are included in the control group and hence the analysis is conservative. The association of group A-like with impaired consciousness is independent of ang-2 (model 6). Similarly the IE surface antibodies and ang-2 show independent association with impaired consciousness (Model 8A, compare with model 7A). In Model 6B, the association of group A-like expression with CM is not statistically significant when ang-2 was considered. However, the odd ratios of both the unadjusted and ang-2 adjusted are similar in magnitude and direction. $ indicate models that have been published in [8, 10] and repeated here for comparison. ‡ = variables that improved the fit of the model using LR χ² improvement test. PfHRP2 data was obtained for 207 out of the 213 samples.