Table 1 Characteristics of the study population

Age (years)

31.4 (4.2)

31.3 (4.3)

0.73

Region of residence (%)

0.01

   Fukuoka Prefecture

221 (56.2)

438 (57.1)

   Other than Fukuoka Prefecture in Kyushu

148 (37.7)

245 (31.9)

   Okinawa Prefecture

24 (6.1)

84 (11.0)

Presence of one or more older siblings (%)

181 (46.1)

419 (54.6)

0.006

Having ever smoked (%)

125 (31.8)

224 (29.2)

0.36

Family history of allergic rhinitis (%)

224 (57.0)

248 (32.3)

< 0.0001

Education (% years)

0.66

   < 13

93 (23.7)

168 (21.9)

   13 - 14

133 (33.8)

253 (33.0)

   ≥ 15

167 (42.5)

346 (45.1)