Table 3.

Multivariate logistic regression analysis of risk factors associated with a positive malaria rapid diagnostic test (N = 66,756)

Explanatory variable		Odds ratio (95% CI)	P-value	P-trend
Individual factors
Gender	Female	1.0
	Male	0.8 (0.7–0.9)	< 0.001
Age group	≥ 45 years	1.0		< 0.001
	35–44 years	1.4 (1.2–1.8)	0.001
	25–34 years	2.2 (1.8–2.7)	< 0.001
	15–24 years	2.4 (1.9–2.9)	< 0.001
	5–14 years	3.2 (2.7–3.9)	< 0.001
	< 5 years	2.5 (2.0–3.0)	< 0.001
Self-reported fever in last two weeks	No	1.0
	Yes	35.7 (32.3–39.5)	< 0.001
History of travel during last 30 days	No	1.0		< 0.001
	Within Zanzibar	0.8 (0.6–1.0)	0.104
	Outside Zanzibar	2.5 (2.3–2.8)	< 0.001
Malaria prevention
Net access	No access	1.0		< 0.001
	< 80%	0.8 (0.7–0.9)	0.003
	≥ 80%*	0.6 (0.5–0.6)	< 0.001
Slept under an LLIN the previous night	No	1.0
	Yes	0.9 (0.7–0.9)	0.036
IRS in the last 12 months	No	1.0
	Yes	0.8 (0.7–0.9)	0.002
Interaction term: Slept under an LLIN the previous night and household received IRS in the last 12 months		0.7 (0.6–0.8)	< 0.001
Geographical factors
Zone	Pemba	1.0
	Unguja	1.2 (1.0–1.5)	0.034

CI, confidence Interval; LLIN, long-lasting insecticidal net; IRS, indoor residual spraying of household with insecticide