Table 1.

Demographic characteristics and prevalence of atopic conditions of cases and controls

Characteristics*Cases, n (%)
Controls, n (%)
All (n = 388)Matched with siblings (n = 63)Matched with friends (n = 122)Unmatched cases* (n = 239)Siblings (n = 80)Friends (n = 191)Clinic based (n = 177)
Age (y)<4083 (21)18 (29)27 (22)49 (21)19 (24)38 (20)26 (15)
40-4996 (25)15 (24)35 (29)55 (23)22 (28)39 (20)20 (11)
50-59108 (28)16 (25)37 (30)63 (26)24 (30)71 (37)46 (26)
60-6987 (22)12 (19)22 (18)60 (25)10 (13)36 (19)51 (29)
≥7014 (4)2 (3)1 (1)12 (5)5 (6)7 (4)34 (19)
GenderFemale150 (39)20 (32)51 (42)88 (37)49 (61)98 (51)106 (60)
Atopy-related ConditionsAllergies88 (23)4 (6)22 (18)65 (27)10 (13)47 (25)88 (50)
Asthma62 (16)16 (25)26 (21)29 (12)36 (45)51 (27)29 (16)
Eczema15 (4)2 (3)5 (4)10 (4)4 (5)18 (9)10 (6)
At least 1 of the above139 (36)20 (32)43 (35)88 (37)38 (48)92 (48)96 (54)
  • * The numbers of cases matched to siblings, those matched to friend controls, and unmatched cases do not add up to 388 because there is an overlap between cases matched to siblings and friend controls (see Fig. 1).