Table 2—

Characteristics of the study population by age, sex, ethnicity, smoking status and pack-yrs

n (%)Mean±sdMedian (IQR)
Age yrs
 Overall74954.9±12.856.5 (44.7–65.7)
 25–2915 (2.0)
 30–39110 (14.7)
 40–49133 (17.8)
 50–59199 (26.6)
 60–69188 (25.1)
 ≥70104 (13.9)
Sex
 Male406 (54.2)
 Female343 (45.8)
Ethnicity
 New Zealand European654 (87.3)
 Maori#26 (3.5)
 Other68 (9.1)
 Not stated n1
Smoking status
 Never-smoker+ n346
 Current smoker§ n7623.7±18.6 pack-yrs17.8 (9.6–33.9)
 Ex-smoker§ n29732.2±17.2 pack-yrs8.0 (1.8–18.5)
 Overall smokers§ n37315.3±17.9 pack-yrs10.0 (3.0–21.8)
Pack-yrs§
 0–9185 (49.6)
 10–1982 (22.0)
 ≥20106 (28.4)
Atopyƒ350/743 (47.1)
Prematurity##22/749 (2.9)
Early hospitalisation11/749 (1.6)
Child asthma¶¶69/749 (9.2)
Total n749
  • IQR: interquartile range. #: main indigenous ethnic minority in New Zealand; : mainly Asian and Pacific islanders; +: refers to nonsmokers of tobacco cigarettes, since there were 30 smokers of tobacco who did not smoke cigarettes; §: refers to tobacco cigarette smokers; ƒ: based on a positive skin-prick test to one of the test substances (excluding the positive control); ##: based on the answer to the question “Were you born prematurely (≥1 month before the date expected for your birth)?”; ¶¶: based on the response to two questions “Did a doctor ever tell you that you had asthma?” and “How old were you when you had your first attack of asthma?” (<18 yrs).