P59: PATTERNS OF GRASS POLLEN SENSITISATION IN SOUTH AUSTRALIA

Abstract

There is limited data regarding pollen sensitisation patterns in Australia, and a reliance on European studies and extracts for the management of allergic respiratory disease. Retrospective examination of grass pollen skin prick test (SPT) results at a South Australian private practice between January 2003 and March 2017. Data analysed: age, postcode, SPT wheal size to temperate (ryegrass/red top/timothy/meadow fescue/kentucky/brome/sweet vernal) and subtropical (bermuda/johnson/paspalum) grasses. Of 5222 patients (mean age 46, SD 18), 3333 (63.8%) were sensitised to at least one grass pollen. Of these, 97.4% (n = 3246) were sensitised to at least one temperate and 87.3% (n = 2911) were sensitised to at least one subtropical grass pollen. 86.1% (n = 2870) were sensitised to both temperate and subtropical grasses. 12.7% (n = 422) and 1.2% (n = 41) were sensitised only to temperate or subtropical grasses respectively. Of those who were sensitised to a subtropical grass and tested for the other two subtropical pollens (n = 2856), 80.1% were sensitised to all. For those sensitised to a temperate grass and also tested to the six other temperate pollens, 95.8% were sensitised to rye grass, while 99.4% were sensitised to rye, timothy, brome and/or sweet vernal grass. No significant difference was seen between the proportion of grass-sensitised patients living in urban or rural areas sensitised to temperate grasses (98.0% and 95.3% respectively) or subtropical grasses (87.0% and 88.4% respectively) (P = 0.49). In South Australia, co-sensitisation to temperate and subtropical grasses is common. This should be taken into account when prescribing immunotherapy, in particular sublingual extracts, which are limited to temperate grasses. Unique sensitisation to only one or two subtropical species is not uncommon. While sensitisation to rye grass is found in most temperate grass-sensitised patients, polysensitisation is common and a significant minority are not sensitised to rye grass; testing a minimum of 3–4 temperate grasses identifies 99.4% of temperate grass sensitised individuals.