Table 2.

Adjusted prevalence ratios and corresponding 95% confidence intervals of the association between the presence of antibodies against C. burnetii, and characteristics/exposures, the Netherlands, March 2014–February 2015

	Participants (%) (n = 2296)	Prevalence ratio (95% CI)a	p-value
Age
< 40 years old	177 (7.7)	Reference
40–60 years old	1045 (45.5)	1.0 (0.5–1.8)	0.93
> 60 years old	1074 (46.8)	1.1 (0.7–1.7)	0.77
Ever smoked	1262 (55.1)	0.8 (0.6–1.0)	0.09
Female gender	1240 (54.0)	0.8 (0.6–0.9)	0.01
Educational level
Low	592 (25.8)	Reference
Middle	1027 (44.7)	0.8 (0.6–1.0)	0.03
High	677 (29.5)	0.7 (0.4–1.0)	0.06
Animal farms
Presence of Q fever affected goat farmb
within > 2000 m	2038 (88.8)	Reference
within 1500–2000 m	139 (6.1)	1.2 (0.6–2.5)	0.53
within 1000–1500 m	91 (4.0)	2.2 (1.1–4.3)	0.02
within 500–1000 m	24 (1.1)	4.5 (2.6–7.7)	< 0.01
within < 500 m	4 (0.2)	9.5 (2.8–31.6)	< 0.01
Presence of goat farm (yes/no)
within 1000 mb	159 (6.9)	3.0 (1.4–6.4)	< 0.01
within 500 mc	40 (1.7)	2.0 (0.7–5.7)	0.19
Presence of sheep farm (yes/no)
within 1000 mb	391 (17.0)	1.4 (0.7–2.8)	0.28
within 500 mc	120 (5.2)	1.2 (0.5–3.2)	0.69
Presence of cattle farm (yes/no)
within 1000 mb	2154 (93.8)	1.2 (0.5–3.3)	0.69
within 500 mc	1130 (49.2)	1.1 (0.9–1.4)	0.18
Farm animalsd
> 50 goats within 1000 m	249 (10.8)	1.9 (1.2–3.0)	< 0.01
> 50 sheep within 1000 m	619 (27.0)	1.2 (0.7–2.0)	0.43
Number of cattle within 1000 m (tertiles)
≤ 314	752 (32.8)	Reference
315–834	766 (33.4)	1.0 (0.6–1.6)	1.00
≥ 835	778 (33.9)	1.0 (0.7–1.5)	0.85

^aAdjusted for gender, age (categorised as < 40, 40–60 and > 60 years old), educational level (low, middle and high), and smoking (ever smoked? yes/no)

^bAdjusted for the presence of other animal farms within 1000 m (goat, sheep and cattle)

^cAdjusted for the presence of other animal farms within 500 m (goat, sheep and cattle)

^dAdjusted for the presence of other farm animals (goat, sheep and cattle)

entries in bold are all p-values