TABLE 1

Description of exposures and potential confounders for males (n=860) and females (n=1191) in the study population (n=2051)

MissingMalesFemalesChi-squared test p-value
Nickel allergy52 (2.5%)<0.001
 Never772 (89.8%)788 (66.2%)
 Ever67 (7.8%)372 (31.2%)
Pierced ears6 (0.3%)<0.001
 Yes162 (18.8%)1082 (90.8%)
Smoking status14 (0.7%)<0.001
 Ever260 (30.2%)458 (38.5%)
Parental SES29 (1.4%)0.37
 High#513 (59.7%)677 (56.8%)
Participants' SES10 (0.5%)0.09
 High#487 (56.6%)718 (60.3%)
Study centre0 (0.0%)0.43
 Dresden428 (49.8%)615 (51.6%)
Parental history of asthma55 (2.7%)0.30
 Yes88 (10.2%)103 (8.6%)
Parental history of rhinitis43 (2.1%)0.17
 Yes312 (36.3%)398 (33.2%)

SES: socioeconomic status. #: ≥12 years of school attendance for participant or at least one parent; : at least one parent ever had asthma or rhinitis.