Malaria risk in young male travellers but local transmission persists: a case–control study in low transmission Namibia

Table 3 Modification of the effect of travel to Angola on malaria by gender in unadjusted and adjusted analyses

	No travel to Angola		Travel to Angola		ORs (95% CI) for travel within gender strata
	N with/without malaria	OR (95% CI)	N with/without malaria	OR (95% CI)	ORs (95% CI) for travel within gender strata
Unadjusted OR^a
Female	34/352	1.0	3/13	1.14 (0.88–1.47)	1.14 (0.88–1.47)
Male	46/266	1.10 (1.04–1.17)	15/3	4.97 (1.59–15.52)	4.50 (1.45–14.01)
Adjusted OR^b
Female	34/352	1.0	3/13	1.65 (0.36–7.47)	1.65 (0.36–7.47)
Male	46/266	1.95 (1.25–3.04)	15/3	85.00 (4.16–1736)	43.58 (2.12–896)

Measure of effect modification on additive scale: RERI (95% CI) 82.39 (−174 to 339); P = 0.53. Confidence intervals calculated using Delta approximation
Measure of effect modification on multiplicative scale: ratio of ORs (95% CI) 26.46 (0.92–766); P = 0.05
^aGEE adjusted for health district (matching variable) and clustering of controls within households
^bORs are adjusted for all covariates listed in Table 4