Microgeographic factors and patterns of aeroallergen sensitisation.
OBJECTIVE
To examine patterns of airborne allergen (aeroallergen) sensitisation in the Greater Sydney area (Sydney), and their relationships with climate, coastal proximity and environment (urban v regional).


METHODS
Retrospective cross-sectional study of patients who underwent aeroallergen skin prick testing at three Sydney allergy clinics, January 2001 - October 2014.


METHODS
Proportions of patients sensitised to specific aeroallergen types; relationships between sensitisation patterns and climate and geography.


RESULTS
Of 1421 patients who met the selection criteria (mean age, 28.3 years [SD, 21.3]; 53.3% were female), 1092 (76.8%) were sensitised to at least one aeroallergen. Those living less than 15 km from the coast were less commonly sensitised to cockroach (< 15 km, 15.1%; 15-30 km, 40.0%; > 30 km, 39.7%; P < 0.001) and grass aeroallergens (< 15 km, 36.5%; 15-30 km, 52.2%; > 30 km, 58.1%; P < 0.001) than patients further inland; the same applied to mould, weed and tree aeroallergens. Subtropical grass sensitisation was more common in temperate/warm summer climates (about 50%) than in temperate/hot summer (27.1%) or subtropical climates (15%) (P < 0.001), and less common in urban (36.7%) than in regional areas (54%; P = 0.014). 72.4% of grass-sensitised patients were co-sensitised to both temperate and subtropical grasses. A selected ten-aeroallergen skin prick test panel identified 98.5% of atopic patients in this Sydney sample.


CONCLUSIONS
Environmental and geographic factors are associated with different patterns of allergic sensitisation in Sydney. Extensive co-sensitisation to subtropical and temperate grasses has implications for immunotherapy in Australia, where most currently available therapies are based on formulations directed at temperate grasses only.
University of New South Wales, Sydney, NSW andrew.kam@hotmail.com.
Andrew W
AW
Kam
St Vincent's Hospital, Sydney, NSW.
Winnie Wy
WW
Tong
St Vincent's Centre for Applied Medical Research, University of New South Wales, Sydney, NSW.
Jenna M
JM
Christensen
Western Sydney University, Sydney, NSW.
Constance H
CH
Katelaris
St Vincent's Clinic, Sydney, NSW.
Janet
J
Rimmer
St Vincent's Centre for Applied Medical Research, University of New South Wales, Sydney, NSW.
Richard J
RJ
Harvey
D000293:Adolescent; D000328:Adult; D000485:Allergens / Q000032:analysis*; D001315:Australia; D002648:Child; D002980:Climate; D003430:Cross-Sectional Studies; D005260:Female; D005843:Geography; D006801:Humans; D008297:Male; D008875:Middle Aged; D052638:Particulate Matter / Q000032:analysis*; D012189:Retrospective Studies; D012882:Skin Tests; D055815:Young Adult
D000485:Allergens; D052638:Particulate Matter