Table 2.

The association of different demographic covariates and dried blood spot quality on measles IgG seropositivity, from a logistic regression model. Participants were from Tianjin, China, 2011–2015. N=3,316.

		% IgG Positive	Odds ratio	95% Confidence Limits		P-value
Number of adequate spots	(continuous)		1.045	0.975	1.120	0.2127
Age	0–2 months	33.8%	0.516	0.206	1.290	<0.0001
	3–5 months	14.8%	0.111	0.046	0.269
	6–8 months	23.1%	0.110	0.051	0.236
	9–11 months	94.0%	15.19	5.069	45.521
	1–9 years	97.7%	5.859	2.319	14.807
	10–19 years	89.4%	1.124	0.678	1.861
	20–29 years	87.3%	ref
	30–39 years	84.8%	0.672	0.504	0.897
	40–49 years	94.4%	1.753	1.002	3.066
Urbanicity	Urban	75.3%	ref			0.4137
	Suburban	76.7%	0.924	0.688	1.242
	Rural	75.4%	1.136	0.880	1.467
Residency	Local	75.6%	ref			0.4295
	Non-local	77.2%	0.870	0.617	1.228
Sex	Male	79.1%	ref			0.0549
	Female	69.9%	1.298	0.995	1.695
Year	2011	83.3%	ref			<0.0001
	2012	72.7%	0.245	0.102	0.590
	2013	77.4%	0.276	0.109	0.699
	2014	86.1%	0.203	0.077	0.540
	2015	66.1%	0.107	0.040	0.285
Season	Spring	76.9%	1.255	0.952	1.655	0.0472
	Summer	73.6%	ref
	Fall	72.1%	0.824	0.583	1.164
	Winter	83.6%	1.469	0.885	2.439
Participant type	Case	92.8%	5.361	2.693	10.672	<0.0001
	Infant	89.6%	1.453	1.067	1.980
	Mother	37.2%	ref
	Community	83.3%	0.213	0.089	0.512