Table 4. Unadjusted and adjusted odds ratios for anti-DENV IgG and anti-CHIKV IgG seropositivity among blood donors residing in Qatar but from different regions.

Characteristic	Unadjusted Odds Ratio				Adjusted Odds Ratioa
	Anti-DENV IgG UOR (95% CI)	P value	Anti-CHIKV IgG UOR (95% CI)	P value	Anti-DENV IgG AOR (95% CI)	P value	Anti-CHIKV IgG AOR (95% CI)	P value
Region
Asia	Ref		Ref		Ref		Ref
Middle East	0.05 (0.03–0.06)	<0.001	0.09 (0.05–0.16)	<0.001	0.05 (0.04–0.07)	<0.001	0.14 (0.07–0.27)	<0.001
North Africa	0.14 (0.10–0.20)	<0.001	0.37 (0.20–0.67)	0.001	0.14 (0.10–0.20)	<0.001	0.50 (0.26–0.96)	0.038
Qatar	0.01 (0.01–0.03)	<0.001	0.23 (0.10–0.53)	<0.001	0.01 (0.01–0.03)	<0.001	0.38 (0.15–0.96)	0.041
Age group (years)
≤ 24	Ref		Ref		Ref		Ref
25–29	2.51 (1.44–4.36)	0.001	1.95 (0.64–5.97)	0.243	1.20 (1.05–3.79)	0.035	1.23 (0.39–3.89)	0.721
30–34	2.98 (1.74–5.08)	<0.001	1.95 (0.66–5.80)	0.229	2.38 (1.28–4.41)	0.006	1.21 (0.40–3.70)	0.740
35–39	2.58 (1.50–4.43)	0.001	1.02 (0.31–3.29)	0.978	2.42 (1.30–4.51)	0.006	0.69 (0.21–2.29)	0.541
40–44	2.30 (1.32–4.01)	0.003	1.84 (0.60–5.70)	0.288	2.40 (1.25–4.56)	0.008	1.42 (0.45–4.52)	0.551
45–49	2.87 (1.60–5.16)	<0.001	2.62 (0.83–8.28)	0.102	2.26 (1.13–4.50)	0.021	1.65 (0.51–5.42)	0.406
≥ 50	2.48 (1.37–4.50)	0.003	1.51 (0.43–5.25)	0.517	3.18 (1.61–6.28)	0.001	1.28 (0.36–4.59)	0.704
Anti-DENV IgG positive	—	—	4.68 (2.98–7.34)	<0.001	—	—	1.94 (1.09–3.44)	0.024
Anti-CHIKV IgG positive	4.68 (2.98–7.34)	<0.001	—	—	1.94 (1.09–3.44)	0.024	—	—

^a Adjusted for nationality, age, and other arbovirus seropositivity (i.e. anti-DENV seropositivity status as predictor of anti-CHIKV seropositivity, and vice versa). For this analysis, n = 1,989 given missing age information for three individuals.